Herein,Co/CoO heterojunction nanoparticles(NPs)rich in oxygen vacancies embedded in mesoporous walls of nitrogen-doped hollow carbon nanoboxes coupled with nitrogen-doped carbon nanotubes(P-Co/CoOV@NHCNB@NCNT)are well...Herein,Co/CoO heterojunction nanoparticles(NPs)rich in oxygen vacancies embedded in mesoporous walls of nitrogen-doped hollow carbon nanoboxes coupled with nitrogen-doped carbon nanotubes(P-Co/CoOV@NHCNB@NCNT)are well designed through zeolite-imidazole framework(ZIF-67)carbonization,chemical vapor deposition,and O_(2) plasma treatment.As a result,the threedimensional NHCNBs coupled with NCNTs and unique heterojunction with rich oxygen vacancies reduce the charge transport resistance and accelerate the catalytic reaction rate of the P-Co/CoOV@NHCNB@NCNT,and they display exceedingly good electrocatalytic performance for oxygen reduction reaction(ORR,halfwave potential[EORR,1/2=0.855 V vs.reversible hydrogen electrode])and oxygen evolution reaction(OER,overpotential(η_(OER,10)=377mV@10mA cm^(−2)),which exceeds that of the commercial Pt/C+RuO_(2) and most of the formerly reported electrocatalysts.Impressively,both the aqueous and flexible foldable all-solid-state rechargeable zinc-air batteries(ZABs)assembled with the P-Co/CoOV@NHCNB@NCNT catalyst reveal a large maximum power density and outstanding long-term cycling stability.First-principles density functional theory calculations show that the formation of heterojunctions and oxygen vacancies enhances conductivity,reduces reaction energy barriers,and accelerates reaction kinetics rates.This work opens up a new avenue for the facile construction of highly active,structurally stable,and cost-effective bifunctional catalysts for ZABs.展开更多
Transition metal sulfides have high theoretical capacities and are considered as potential anode materials for sodium-ion batteries.However,due to low inherent conductivity and significant volume expansion,the electro...Transition metal sulfides have high theoretical capacities and are considered as potential anode materials for sodium-ion batteries.However,due to low inherent conductivity and significant volume expansion,the electrochemical performance is greatly limited.In this study,a nickel/manganese sulfide material(Ni_(0.96)S_(x)/MnS_(y)-NC)with adjustable sulfur vacancies and heterogeneous hollow spheres was prepared using a simple method.The introduction of a concentration-adjustable sulfur vacancy enables the generation of a heterogeneous interface between bimetallic sulfide and sulfur vacancies.This interface collectively creates an internal electric field,improving the mobility of electrons and ions,increasing the number of electrochemically active sites,and further optimizing the performance of Na~+storage.The direction of electron flow is confirmed by Density functional theory(DFT)calculations.The hollow nano-spherical material provides a buffer for expansion,facilitating rapid transfer kinetics.Our innovative discovery involves the interaction between the ether-based electrolyte and copper foil,leading to the formation of Cu_9S_5,which grafts the active material and copper current collector,reinforcing mechanical supporting.This results in a new heterostructure of Cu_9S_5 with Ni_(0.96)S_(x)/MnS_(y),contributing to the stabilization of structural integrity for long-cycle performance.Therefore,Ni_(0.96)S_(x)/MnS_(y)-NC exhibits excellent electrochemical properties following our modification route.Regarding stability performance,Ni0_(.96)S_(x)/MnS_(y)-NC demonstrates an average decay rate of 0.00944%after 10,000 cycles at an extremely high current density of 10000 mA g^(-1),A full cell with a high capacity of 304.2 mA h g^(-1)was also successfully assembled by using Na_(3)V_(2)(PO_(4))_(3)/C as the cathode.This study explores a novel strategy for interface/vacancy co-modification in the fabrication of high-performance sodium-ion batteries electrode.展开更多
It is urgent to develop catalysts with application potential for oxidative coupling of methane(OCM)at relatively lower temperature.Herein,three-dimensional ordered macro porous(3 DOM)La_(2-x)Sr_(x)Ce_(2-y)CayO_(7-δ)(...It is urgent to develop catalysts with application potential for oxidative coupling of methane(OCM)at relatively lower temperature.Herein,three-dimensional ordered macro porous(3 DOM)La_(2-x)Sr_(x)Ce_(2-y)CayO_(7-δ)(A_(2)B_(2)O_(7)-type)catalysts with disordered defective cubic fluorite phased structure were successfully prepared by a colloidal crystal template method.3DOM structure promotes the accessibility of the gaseous reactants(O2and CH4)to the active sites.The co-doping of Ca and Sr ions in La_(2-x)Sr_(x)Ce_(2-y)CayO_(7-δ)catalysts improved the formation of oxygen vacancies,thereby leading to increased density of surface-active oxygen species(O_(2)^(-))for the activation of CH4and the formation of C2products(C2H6and C2H4).3DOM La_(2-x)Sr_(x)Ce_(2-y)CayO_(7-δ)catalysts exhibit high catalytic activity for OCM at low temperature.3DOM La1.7Sr0.3Ce1.7Ca0.3O7-δcatalyst with the highest density of O_(2)^(-)species exhibited the highest catalytic activity for low-temperature OCM,i.e.,its CH4conversion,selectivity and yield of C2products at 650℃are 32.2%,66.1%and 21.3%,respectively.The mechanism was proposed that the increase in surface oxygen vacancies induced by the co-doping of Ca and Sr ions boosts the key step of C-H bond breaking and C-C bond coupling in catalyzing low-temperature OCM.It is meaningful for the development of the low-temperature and high-efficient catalysts for OCM reaction in practical application.展开更多
Manganese-based oxide electrode materials suffer from severe Jahn-Teller(J-T)distortion,leading to severe cycle instability in sodium ion storage.However,it is difficult to adjust the electron at d orbitals exactly to...Manganese-based oxide electrode materials suffer from severe Jahn-Teller(J-T)distortion,leading to severe cycle instability in sodium ion storage.However,it is difficult to adjust the electron at d orbitals exactly to a low spin state to eliminate orbital degeneracy and suppress J-T distortion fundamentally.This article constructed concentration-controllable Mn/O coupled vacancy and amorphous network in Mn_(3)O_(4) and coated it with nitrogen-doped carbon aerogel(Mn_(3-x)O_(4-y)@NCA).The existence of Mn/O vacancies has been confirmed by scanning transmission electron microscopy(STEM)and positron annihilation lifetime spectroscopy(PALS).Atomic absorption spectroscopy(AAS)and X-ray photoelectron spectroscopy(XPS)determine the most optimal ratio of Mn/O vacancies for sodium ion storage is 1:2.Density functional theory(DFT)calculations prove that Mn/O coupled vacancies with the ratio of 1:2could exactly induce a low spin states and a d~4 electron configuration of Mn,suppressing the J-T distortion successfully.The abundant amorphous regions can shorten the transport distance of sodium ions,increase the electrochemically active sites and improve the pseudocapacitance response.From the synergetic effect of Mn/O coupled vacancies and amorphous regions,Mn_(3-x)O_(4-y)@NCA exhibits an energy density of 37.5 W h kg^(-1)and an ultra-high power density of 563 W kg^(-1)in an asymmetric supercapacitor.In sodium-ion batteries,it demonstrates high reversible capacity and exceptional cycling stability.This research presents a new method to improve the Na^(+)storage performance in manganese-based oxide,which is expected to be generalized to other structural distortion.展开更多
The recent emergence of tetragonal phases zirconium dioxide(ZrO_(2))with vacancies has generated significant interest as a highly efficient and stable electrocatalyst with potential applications in trapping polysulfid...The recent emergence of tetragonal phases zirconium dioxide(ZrO_(2))with vacancies has generated significant interest as a highly efficient and stable electrocatalyst with potential applications in trapping polysulfides and facilitating rapid conversion in lithium-sulfur batteries(LSBs).However,the reduction of ZrO_(2)is challenging,even under strong reducing atmospheres at high temperatures and pressures.Consequently,the limited presence of oxygen vacancies results in insufficient active sites and reaction interfaces,thereby hindering practical implementation.Herein,we successfully introduced abundant oxygen vacancies into ZrO_(2)at the nanoscale with the help of carbon nanotubes(CNTs-OH)through hydrogen-etching at lower temperatures and pressures.The introduced oxygen vacancies on ZrO_(2-x)/CNTs-OH can effectively rearrange charge distribution,enhance sulfiphilicity and increase active sites,contributing to high ionic and electronic transfer kinetics,strong binding energy and low redox barriers between polysulfides and ZrO_(2-x).These findings have been experimentally validated and supported by theory calculations.As a result,LSBs assembled with the ZrO_(2-x)/CNTs-OH modified separators demonstrate excellent rate performance,superior cycling stability,and ultra-high sulfur utilization.Especially,at high sulfur loading of 6 mg cm^(-2),the area capacity is still up to 6.3 mA h cm^(-2).This work provides valuable insights into the structural and functional optimization of electrocatalysts for batteries.展开更多
Steam reforming of long-chain hydrocarbon fuels for hydrogen production has received great attention for thermal management of the hypersonic vehicle and fuel-cell application.In this work,Pt catalysts supported on Ce...Steam reforming of long-chain hydrocarbon fuels for hydrogen production has received great attention for thermal management of the hypersonic vehicle and fuel-cell application.In this work,Pt catalysts supported on CeO_(2)and Tb-doped CeO_(2)were prepared by a precipitation method.The physical structure and chemical properties of the as-prepared catalysts were characterized by powder X-ray diffraction,scanning electron microscopy,transmission electron microscopy,Raman spectroscopy,H_(2)temperature programmed reduction,and X-ray photoelectron spectroscopy.The results show that Tb-doped CeO_(2)supported Pt possesses abundant surface oxygen vacancies,good inhibition of ceria sintering,and strong metal-support interaction compared with CeO_(2)supported Pt.The catalytic performance of hydrogen production via steam reforming of long-chain hydrocarbon fuels(n-dodecane)was tested.Compared with 2Pt/CeO_(2),2Pt/Ce_(0.9)Tb_(0.1)O_(2),and 2Pt/Ce_(0.5)Tb_(0.5)O_(2),the 2Pt/Ce_(0.7)Tb_(0.3)O_(2)has higher activity and stability for hydrogen production,on which the conversion of n-dodecane was maintained at about 53.2%after 600 min reaction under 700℃at liquid space velocity of 9 ml·g^(-1)·h^(-1).2Pt/CeO_(2)rapidly deactivated,the conversion of n-dodecane was reduced to only 41.6%after 600 min.展开更多
Synergistic regulation of hierarchical nanostructures and defect engineering is effective in accelerating electron and ion transport for metal oxide electrodes.Herein,carbon nanofiber-supported V_(2)O_(3) with enriche...Synergistic regulation of hierarchical nanostructures and defect engineering is effective in accelerating electron and ion transport for metal oxide electrodes.Herein,carbon nanofiber-supported V_(2)O_(3) with enriched oxygen vacancies(OV-V_(2)O_(3)@CNF)was fabricated using the facile electrospinning method,followed by thermal reduction.Differing from the traditional particles embedded within carbon nanofibers or irregularly distributed between carbon nanofibers,the free-standing OV-V_(2)O_(3)@CNF allows for V_(2)O_(3) nanosheets to grow vertically on one-dimensional(1D)carbon nanofibers,enabling abundant active sites,shortened ion diffusion pathway,continuous electron transport,and robust structural stability.Meanwhile,density functional theory calculations confirmed that the oxygen vacancies can promote intrinsic electron conductivity and reduce ion diffusion energy barrier.Consequently,the OV-V_(2)O_(3)@CNF anode delivers a large reversible capacity of 812 mAh g^(-1) at 0.1 A g^(-1),superior rate capability(405 mAh g^(-1) at 5 A g^(-1)),and long cycle life(378 mAh g^(-1) at 5 A g^(-1) after 1000 cycles).Moreover,an all-vanadium full battery(V2O5//OV-V_(2)O_(3)@CNF)was assembled using an OV-V_(2)O_(3)@CNF anode and a V2O5 cathode,which outputs a working voltage of 2.5 V with high energy density and power density,suggesting promising practical application.This work offers fresh perspectives on constructing hierarchical 1D nanofiber electrodes by combining defect engineering and electrospinning technology.展开更多
The experimental results in previous studies have indicated that during the ductile fracture of pure metals,vacancies aggregate and form voids at grain boundaries.However,the physical mechanism underlying this phenome...The experimental results in previous studies have indicated that during the ductile fracture of pure metals,vacancies aggregate and form voids at grain boundaries.However,the physical mechanism underlying this phenomenon remains not fully understood.This study derives the equilibrium distribution of vacancies analytically by following thermodynamics and the micromechanics of crystal defects.This derivation suggests that vacancies cluster in regions under hydrostatic compression to minimize the elastic strain energy.Subsequently,a finite element model is developed for examining more general scenarios of interaction between vacancies and grain boundaries.This model is first verified and validated through comparison with some available analytical solutions,demonstrating consistency between finite element simulation results and analytical solutions within a specified numerical accuracy.A systematic numerical study is then conducted to investigate the mechanism that might govern the micromechanical interaction between grain boundaries and the profuse vacancies typically generated during plastic deformation.The simulation results indicate that the reduction in total elastic strain energy can indeed drive vacancies toward grain boundaries,potentially facilitating void nucleation in ductile fracture.展开更多
Cu/ZnO is widely used in the hydrogenation of carbon dioxide (CO_(2)) to methanol (CH_(3)OH) to improve the lowconversion rate and selectivity generally observed. In this work, a series of In, Zr, Co, and Ni-doped CuO...Cu/ZnO is widely used in the hydrogenation of carbon dioxide (CO_(2)) to methanol (CH_(3)OH) to improve the lowconversion rate and selectivity generally observed. In this work, a series of In, Zr, Co, and Ni-doped CuO-ZnO catalysts wassynthesized via a hydrothermal method. By introducing a second metal element, the activity and dispersion of the activesites can be adjusted and the synergy between the metal and the carrier can be enhanced, forming an abundance of oxygenvacancies. Oxygen vacancies not only adsorb CO_(2) but also activate the intermediates in methanol synthesis, playing a keyrole in the entire reaction. Co3O4-CuO-ZnO had the best catalytic performance (a CO_(2) conversion rate of 9.17%;a CH_(3)OHselectivity of 92.77%). This study describes a typical strategy for multi-component doping to construct a catalyst with anabundance of oxygen vacancies, allowing more effective catalysis to synthesize CH_(3)OH from CO_(2).展开更多
The synthesis of oxygen vacancies(OVs)-modified TiO_(2)under mild conditions is attractive.In this work,OVs were easily introduced in TiO_(2)lattice during the hydrothermal doping process of trivalent iron ions.Theore...The synthesis of oxygen vacancies(OVs)-modified TiO_(2)under mild conditions is attractive.In this work,OVs were easily introduced in TiO_(2)lattice during the hydrothermal doping process of trivalent iron ions.Theoretical calculations based on a novel charge-compensation structure model were employed with experimental methods to reveal the intrinsic photocatalytic mechanism of Fe-doped TiO_(2)(Fe-TiO_(2)).The OVs formation energy in Fe-TiO_(2)(1.12 eV)was only 23.6%of that in TiO_(2)(4.74 eV),explaining why Fe^(3+)doping could introduce OVs in the TiO_(2)lattice.The calculation results also indicated that impurity states introduced by Fe^(3+)and OVs enhanced the light absorption activity of TiO_(2).Additionally,charge carrier transport was investigated through the carrier lifetime and relative mass.The carrier lifetime of Fe-TiO_(2)(4.00,4.10,and 3.34 ns for 1at%,2at%,and 3at%doping contents,respectively)was longer than that of undoped TiO_(2)(3.22 ns),indicating that Fe^(3+) and OVs could promote charge carrier separation,which can be attributed to the larger relative effective mass of electrons and holes.Herein,Fe-TiO_(2)has higher photocatalytic indoor NO removal activity compared with other photocatalysts because it has strong light absorption activity and high carrier separation efficiency.展开更多
Low-cost and flexible solid polymer electrolytes are promising in all-solid-state Li-metal batteries with high energy density and safety.However,both the low room-temperature ionic conductivities and the small Li^(+)t...Low-cost and flexible solid polymer electrolytes are promising in all-solid-state Li-metal batteries with high energy density and safety.However,both the low room-temperature ionic conductivities and the small Li^(+)transference number of these electrolytes significantly increase the internal resistance and overpotential of the battery.Here,we introduce Gd-doped CeO_(2) nanowires with large surface area and rich surface oxygen vacancies to the polymer electrolyte to increase the interaction between Gd-doped CeO_(2) nanowires and polymer electrolytes,which promotes the Li-salt dissociation and increases the concentration of mobile Li ions in the composite polymer electrolytes.The optimized composite polymer electrolyte has a high Li-ion conductivity of 5×10^(-4)4 S cm^(-1) at 30℃ and a large Li+transference number of 0.47.Moreover,the composite polymer electrolytes have excellent compatibility with the metallic lithium anode and high-voltage LiNi_(0.8)Mn _(0.1)Co_(0.1)O_(2)(NMC)cathode,providing the stable cycling of all-solid-state batteries at high current densities.展开更多
Electrocatalytic CO_(2)reduction reaction to low-carbon alcohol is a challenging task,especially high selectivity for ethanol,which is mainly limited by the regulation of reaction intermediates and subsequent C–C cou...Electrocatalytic CO_(2)reduction reaction to low-carbon alcohol is a challenging task,especially high selectivity for ethanol,which is mainly limited by the regulation of reaction intermediates and subsequent C–C coupling.A Cu-Co bimetallic catalyst with CN vacancies is successfully developed by H_(2)cold plasma toward a high-efficiency CO_(2)RR into low-carbon alcohol.The Cu-Co PBA-V_(CN)(Prussian blue analogues with CN vacancies)electrocatalyst yields methanol and ethanol as major products with a total low-carbon alcohol FE of 83.8%(methanol:39.2%,ethanol:44.6%)at-0.9 V vs.RHE,excellent durability(100 h)and a small onset potential of-0.21 V.ATR-SEIRAS(attenuated total internal reflection surface enhanced infrared absorption spectroscopy)and DFT(density functional theory)reveal that the steric hindrance of V_(CN)can enhance the CO generation from*COOH,and the C–C coupling can also be increased by CO spillover on uniformly dispersed Cu atoms.This work provides a strategy for the design and preparation of electrocatalysts for CO_(2)RR into low-carbon alcohol products and highlights the impact of catalyst steric hindrance to catalytic performance.展开更多
Developing highly-active,earth-abundant non-precious-metal catalysts for hydrogen evolution reaction(HER)in alkaline solution would be beneficial to sustainable energy storage.Perovskite oxides are generally regarded ...Developing highly-active,earth-abundant non-precious-metal catalysts for hydrogen evolution reaction(HER)in alkaline solution would be beneficial to sustainable energy storage.Perovskite oxides are generally regarded as low-active HER catalysts,due to their inapposite hydrogen adsorption and water dissociation.Here,we report a detailed study on perovskite LaCoO_(3)epitaxial thin films as a model catalyst to significantly enhance the HER performance via an electrochemical activation process.As a result,the overpotential for the activation films to achieve a current density of 0.36 m A/cm^(2)is 238 m V,reduced by more than 200 m V in comparison with that of original samples.Structural characterization revealed the activation process dramatically increases the concentration of oxygen vacancies(Vo)on the surface of LaCoO_(3).We established the relationship between the electronic structure induced by Vo and the enhanced HER activity.Further theoretical calculations revealed that the Vo optimizes the hydrogen adsorption and dissociation of water on the surface of LaCoO_(3)thin films,thus improving the HER catalytic activity.This work may promote a deepened understanding of perovskite oxides for HER mechanism by Vo adjusting and a new avenue for designing highly active electrochemical catalysts in alkaline solution.展开更多
Understanding the crystal phase evolution of bimetallic oxide anodes is the main concern to profoundly reveal the conversion reaction kinetics and sodium-ion storage mechanisms.Herein,an integrated selfsupporting anod...Understanding the crystal phase evolution of bimetallic oxide anodes is the main concern to profoundly reveal the conversion reaction kinetics and sodium-ion storage mechanisms.Herein,an integrated selfsupporting anode of the Cu-decorated Cu-Mn bimetallic oxides with oxygen vacancies(Ov-BMO-Cu)are in-situ generated by phase separation and hydrogen etching using nanoporous Cu-Mn alloy as selfsacrificial templates.On this basis,we have elucidated the relationship between the phase evolution,oxygen vacancies and sodium-ion storage mechanisms,further demonstrating the evolution of oxygen vacancies and the inhibition effect of manganese oxides as an“anchor”on grain aggregation of copper oxides.The kinetic analyses confirm that the expanded lattice space and increased oxygen vacancies of cycled Ov-BMO-Cu synergistically guarantee effective sodium-ion diffusion and storage mechanisms.Therefore,the Ov-BMO-Cu electrode exhibits higher reversible capacities of 4.04 mA h cm^(-2)at 0.2 mA cm^(-2)after 100 cycles and 2.20 m A h cm^(-2)at 1.0 mA cm^(-2)after 500 cycles.Besides,the presodiated Ov-BMO-Cu anode delivers a considerable reversible capacity of 0.79 m A h cm^(-2)at 1.0 mA cm^(-2)after 60 cycles in full cells with Na_(3)V_(2)(PO_(4))_(3)cathode,confirming its outstanding practicality.Thus,this work is expected to provide enlightenment for designing high-capacity bimetallic oxide anodes.展开更多
Achieving high-efficiency sodium storage in metal selenides is still severely constrained in consideration of their inferior electronic conductivity and inadequate Na^(+)insertion pathways and active sites.Heteroatom ...Achieving high-efficiency sodium storage in metal selenides is still severely constrained in consideration of their inferior electronic conductivity and inadequate Na^(+)insertion pathways and active sites.Heteroatom doping accompanied by spontaneously developed lattice defects can effectively tune electronic structure of metal selenides,which give a strong effect to motivate fast charge transfer and Na^(+)accessibility.Herein,we finely designed and successfully constructed a fascinating phosphorus-doped Cu_(2)Se@C hollow nanosphere with abundant vacancy defects(Cu_(2)P_(x)Se_(1-x)@C)through a combination strategy of selenization of Cu_(2)O nanosphere template,self-polymerization of dopamine,and subsequent phosphorization treatment.Such exquisite composite possesses enriched active sites,superior conductivity,and sufficient Na^(+)insertion channel,which enable much faster Na^(+)diffusion rates and more remarkable pseudocapacitive features,Satisfyingly,the Cu_(2)P_(x)Se_(1-x)@C composites manifest the supernormal sodium-storage capabilities,that is,a reversible capacity of 403.7 mA h g^(-1) at 1.0 A g^(-1) over 100 cycles,and an ultrastable cyclic lifespan over 1000 cycles at 20.0 A g^(-1) with a high capacity-retention of about249.7 mA h g^(-1).The phase transformation of the Cu_(2)P_(x)Se_(1-x)@C involving the intercalation of Na^(+)into Cu_(2)Se and the following conversion of NaCuSe to Cu and Na2Se were further demonstrated through a series of ex-situ characterization methods.DFT results demonstrate that the coexistence of phosphorusdoping and vacancy defects within Cu_(2)Se results in the reduction of Na^(+)adsorption energy from-1.47to-1.56 eV improving the conductivity of Cu_(2)Se to further accelerate fast Na^(+)mobility.展开更多
Rational design and construction of highly efficient nonprecious electrocatalysts for oxygen reduction and alcohols oxidation reactions(ORR,AOR)are extremely vital for the development of direct oxidation alkaline fuel...Rational design and construction of highly efficient nonprecious electrocatalysts for oxygen reduction and alcohols oxidation reactions(ORR,AOR)are extremely vital for the development of direct oxidation alkaline fuel cells,metal-air batteries,and water electrolysis system involving hydrogen and value-added organic products generation,but they remain a great challenge.Herein,a bifunctional electrocatalyst is prepared by anchoring CuS/NiS_(2)nanoparticles with abundant heterointerfaces and sulfur vacancies on graphene(Cu_(1)Ni_(2)-S/G)for ORR and AOR.Benefiting from the synergistic effects between strong interfacial coupling and regulation of the sulfur vacancies,Cu_(1)Ni_(2)-S/G achieves dramatically enhanced ORR activity with long term stability.Meanwhile,when ethanol is utilized as an oxidant for AOR,an ultralow potential(1.37 V)at a current density of 10 mA cm-2 is achieved,simultaneously delivering a high Faradaic efficiency of 96%for ethyl acetate production.Cu_(1)Ni_(2)-S/G also exhibits catalytic activity for other alcohols electrooxidation process,indicating its multifunctionality.This work not only highlights a viable strategy for tailoring catalytic activity through the synergetic combination of interfacial and vacancies engineering,but also opens up new avenues for the construction of a self-driven biomass electrocatalysis system for the generation of value-added organic products and hydrogen under ambient conditions.展开更多
Surface oxygen vacancies(OVs) with abundant localized electrons on bismuth-oxygen based photocatalysts are proved to have the ability to capture and activate CO_(2).However,the surface OVs are easily filled with oxyge...Surface oxygen vacancies(OVs) with abundant localized electrons on bismuth-oxygen based photocatalysts are proved to have the ability to capture and activate CO_(2).However,the surface OVs are easily filled with oxygen-containing species and destroyed,losing their effects as active sites and hindering the subsequent CO_(2)photoreduction.For realistic and sustainable CO_(2)photoreduction,constructing sustainable and stable surface OVs as active sites on photocatalysts is essential.This work shows the synthesis of interlayer stretched Bi_(2)O_(2)CO_(3) ultrathin nanosheets with tensile stress,which are beneficial to continuously generating light-induced dynamic OVs.With sufficient active sites,excellent,stable,and selective photoreduction of CO_(2)to CO under simulated solar light is achieved.The light-induced OVs can reduce the energy barrier of rate-determining step,resulting in the 100% product selectivity.The results presented herein demonstrate the effect of dynamic OVs induced by interlayer tensile strain on catalysts for the enhanced selective CO_(2)photoreduction process.展开更多
Heteroatomic substitution and vacancy engineering of spinel oxides can theoretically optimize the oxygen evolution reaction(OER)through charge redistribution and d-band center modification but still remain a great cha...Heteroatomic substitution and vacancy engineering of spinel oxides can theoretically optimize the oxygen evolution reaction(OER)through charge redistribution and d-band center modification but still remain a great challenge in both the preparation and catalytic mechanism.Herein,we proposed a novel and efficient Ar-plasma(P)-assisted strategy to construct heteroatom Mo-substituted and oxygen vacancies enriched hierarchical spinel Co_(3)O_(4)porous nanoneedle arrays in situ grown on carbon cloth(denoted P-Mo-Co_(3)O_(4)@CC)to improve the OER performance.Ar-plasma technology can efficiently generate vacancy sites at the surface of hydroxide,which induces the anchoring of Mo anion salts through electrostatic interaction,finally facilitating the substitution of Mo atoms and the formation of oxygen vacancies on the Co_(3)O_(4)surface.The P-Mo-Co_(3)O_(4)@CC affords a low overpotential of only 276 mV at 10 mA cm^(−2)for the OER,which is 58 mV superior to that of Mo-free Co_(3)O_(4)@CC and surpasses commercial RuO_(2)catalyst.The robust stability and satisfactory selectivity(nearly 100%Faradic efficiency)of P-Mo-Co_(3)O_(4)@CC for the OER are also demonstrated.Theoreti-cal studies demonstrate that Mo with variable valance states can efficiently regulates the atomic ratio of Co^(3+)/Co^(2+)and increases the number of oxygen vacancies,thereby inducing charge redistribution and tuning the d-band center of Co_(3)O_(4),which improve the adsorption energy of oxygen intermediates(e.g.,*OOH)on P-Mo-Co_(3)O_(4)@CC during OER.Furthermore,the two-electrode OER//HER electrolyzer equipped with P-Mo-Co_(3)O_(4)@CC as anode displays a low operation potential of 1.54 V to deliver a current density of 10 mA cm^(−2),and also exhibits good reversibility and anticurrent fluctuation ability under simulated real energy supply conditions,demonstrating the great potential of P-Mo-Co_(3)O_(4)@CC in water electrolysis.展开更多
In recent years,manganese-based oxides as an advanced class of cathode materials for zinc-ion batteries(ZIBs)have attracted a great deal of attentions from numerous researchers.However,their slow reaction kinetics,lim...In recent years,manganese-based oxides as an advanced class of cathode materials for zinc-ion batteries(ZIBs)have attracted a great deal of attentions from numerous researchers.However,their slow reaction kinetics,limited active sites and poor electrical conductivity inevitably give rise to the severe performance degradation.To solve these problems,herein,we introduce abundant oxygen vacancies into the flower-likeδ-MnO_(2)nanostructure and effectively modulate the vacancy defects to reach the optimal level(δ-MnO_(2)-x-2.0).The smart design intrinsically tunes the electronic structure,guarantees ion chemisorption-desorption equilibrium and increases the electroactive sites,which not only effectively accelerates charge transfer rate during reaction processes,but also endows more redox reactions,as verified by first-principle calculations.These merits can help the fabricatedδ-MnO_(2)-x-2.0 cathode to present a large specific capacity of 551.8 mAh g^(-1) at 0.5 A g^(-1),high-rate capability of 262.2 mAh g^(-1) at 10 A g^(-1) and an excellent cycle lifespan(83%of capacity retention after 1500 cycles),which is far superior to those of the other metal compound cathodes.In addition,the charge/discharge mechanism of theδ-MnO_(2)-x-2.0 cathode has also been elaborated through ex situ techniques.This work opens up a new pathway for constructing the next-generation high-performance ZIBs cathode materials.展开更多
The low-valence cations Na^(+)and Sr^(2+)were selected as the co-dopants to increase the vacancies concentration in the Y_(2.982)Ce_(0.018)Al_(2)Ga_(3)O_(12)phosphor.The successful incorporation of Na^(+)and Sr^(2+)wa...The low-valence cations Na^(+)and Sr^(2+)were selected as the co-dopants to increase the vacancies concentration in the Y_(2.982)Ce_(0.018)Al_(2)Ga_(3)O_(12)phosphor.The successful incorporation of Na^(+)and Sr^(2+)was confirmed by the X-Ray Difiraction(XRD)results.All the samples show 5d-4f green persistent luminescence of Ce^(3+)after 450 nm excitation.The decay curves demonstrate that the persistent luminescence is efiectively enhanced with Na+and Sr2+doping.The thermoluminescence glow curves also show not only does the trap concentration increase,but also the distribution of trap depths is broadened.In addition,the air-and H_(2)/Ar-annealing treatments were conducted on every as-made sample.The experimental results prove that the increased traps after the Na^(+)/Sr^(2+)doping are mainly attributed to the oxygen vacancies,and the traps have a continuous and broad distribution of trap depths.We hope this work could give new inspiration for designing a high-performance persistent phosphor.展开更多
基金the support from the Zhejiang Provincial Natural Science Foundation (No.LR22E070001),the National Natural Science Foundation of China (Nos.12275239 and 11975205)the Guangdong Basic and Applied Basic Research Foundation (No.2020B1515120048).
文摘Herein,Co/CoO heterojunction nanoparticles(NPs)rich in oxygen vacancies embedded in mesoporous walls of nitrogen-doped hollow carbon nanoboxes coupled with nitrogen-doped carbon nanotubes(P-Co/CoOV@NHCNB@NCNT)are well designed through zeolite-imidazole framework(ZIF-67)carbonization,chemical vapor deposition,and O_(2) plasma treatment.As a result,the threedimensional NHCNBs coupled with NCNTs and unique heterojunction with rich oxygen vacancies reduce the charge transport resistance and accelerate the catalytic reaction rate of the P-Co/CoOV@NHCNB@NCNT,and they display exceedingly good electrocatalytic performance for oxygen reduction reaction(ORR,halfwave potential[EORR,1/2=0.855 V vs.reversible hydrogen electrode])and oxygen evolution reaction(OER,overpotential(η_(OER,10)=377mV@10mA cm^(−2)),which exceeds that of the commercial Pt/C+RuO_(2) and most of the formerly reported electrocatalysts.Impressively,both the aqueous and flexible foldable all-solid-state rechargeable zinc-air batteries(ZABs)assembled with the P-Co/CoOV@NHCNB@NCNT catalyst reveal a large maximum power density and outstanding long-term cycling stability.First-principles density functional theory calculations show that the formation of heterojunctions and oxygen vacancies enhances conductivity,reduces reaction energy barriers,and accelerates reaction kinetics rates.This work opens up a new avenue for the facile construction of highly active,structurally stable,and cost-effective bifunctional catalysts for ZABs.
基金financially supported by the National Nature Science Foundation of Jiangsu Province(BK20221259)。
文摘Transition metal sulfides have high theoretical capacities and are considered as potential anode materials for sodium-ion batteries.However,due to low inherent conductivity and significant volume expansion,the electrochemical performance is greatly limited.In this study,a nickel/manganese sulfide material(Ni_(0.96)S_(x)/MnS_(y)-NC)with adjustable sulfur vacancies and heterogeneous hollow spheres was prepared using a simple method.The introduction of a concentration-adjustable sulfur vacancy enables the generation of a heterogeneous interface between bimetallic sulfide and sulfur vacancies.This interface collectively creates an internal electric field,improving the mobility of electrons and ions,increasing the number of electrochemically active sites,and further optimizing the performance of Na~+storage.The direction of electron flow is confirmed by Density functional theory(DFT)calculations.The hollow nano-spherical material provides a buffer for expansion,facilitating rapid transfer kinetics.Our innovative discovery involves the interaction between the ether-based electrolyte and copper foil,leading to the formation of Cu_9S_5,which grafts the active material and copper current collector,reinforcing mechanical supporting.This results in a new heterostructure of Cu_9S_5 with Ni_(0.96)S_(x)/MnS_(y),contributing to the stabilization of structural integrity for long-cycle performance.Therefore,Ni_(0.96)S_(x)/MnS_(y)-NC exhibits excellent electrochemical properties following our modification route.Regarding stability performance,Ni0_(.96)S_(x)/MnS_(y)-NC demonstrates an average decay rate of 0.00944%after 10,000 cycles at an extremely high current density of 10000 mA g^(-1),A full cell with a high capacity of 304.2 mA h g^(-1)was also successfully assembled by using Na_(3)V_(2)(PO_(4))_(3)/C as the cathode.This study explores a novel strategy for interface/vacancy co-modification in the fabrication of high-performance sodium-ion batteries electrode.
基金supported by the National Key Research and Development Program of China(Nos.2022YFB3504100,2022YFB3506200)the National Natural Science Foundation of China(Nos.22208373,22376217)+1 种基金the Beijing Nova Program(No.20220484215)the Science Foundation of China University of Petroleum,Beijing(No.2462023YJRC030)。
文摘It is urgent to develop catalysts with application potential for oxidative coupling of methane(OCM)at relatively lower temperature.Herein,three-dimensional ordered macro porous(3 DOM)La_(2-x)Sr_(x)Ce_(2-y)CayO_(7-δ)(A_(2)B_(2)O_(7)-type)catalysts with disordered defective cubic fluorite phased structure were successfully prepared by a colloidal crystal template method.3DOM structure promotes the accessibility of the gaseous reactants(O2and CH4)to the active sites.The co-doping of Ca and Sr ions in La_(2-x)Sr_(x)Ce_(2-y)CayO_(7-δ)catalysts improved the formation of oxygen vacancies,thereby leading to increased density of surface-active oxygen species(O_(2)^(-))for the activation of CH4and the formation of C2products(C2H6and C2H4).3DOM La_(2-x)Sr_(x)Ce_(2-y)CayO_(7-δ)catalysts exhibit high catalytic activity for OCM at low temperature.3DOM La1.7Sr0.3Ce1.7Ca0.3O7-δcatalyst with the highest density of O_(2)^(-)species exhibited the highest catalytic activity for low-temperature OCM,i.e.,its CH4conversion,selectivity and yield of C2products at 650℃are 32.2%,66.1%and 21.3%,respectively.The mechanism was proposed that the increase in surface oxygen vacancies induced by the co-doping of Ca and Sr ions boosts the key step of C-H bond breaking and C-C bond coupling in catalyzing low-temperature OCM.It is meaningful for the development of the low-temperature and high-efficient catalysts for OCM reaction in practical application.
基金supported by the National Natural Science Foundation of China (22278231,22005165 and 22376110)the Natural Science Foundation Project of Shandong Province (ZR2022MB092 and ZR2023ME098)the Taishan Scholar Program (ts201712030)。
文摘Manganese-based oxide electrode materials suffer from severe Jahn-Teller(J-T)distortion,leading to severe cycle instability in sodium ion storage.However,it is difficult to adjust the electron at d orbitals exactly to a low spin state to eliminate orbital degeneracy and suppress J-T distortion fundamentally.This article constructed concentration-controllable Mn/O coupled vacancy and amorphous network in Mn_(3)O_(4) and coated it with nitrogen-doped carbon aerogel(Mn_(3-x)O_(4-y)@NCA).The existence of Mn/O vacancies has been confirmed by scanning transmission electron microscopy(STEM)and positron annihilation lifetime spectroscopy(PALS).Atomic absorption spectroscopy(AAS)and X-ray photoelectron spectroscopy(XPS)determine the most optimal ratio of Mn/O vacancies for sodium ion storage is 1:2.Density functional theory(DFT)calculations prove that Mn/O coupled vacancies with the ratio of 1:2could exactly induce a low spin states and a d~4 electron configuration of Mn,suppressing the J-T distortion successfully.The abundant amorphous regions can shorten the transport distance of sodium ions,increase the electrochemically active sites and improve the pseudocapacitance response.From the synergetic effect of Mn/O coupled vacancies and amorphous regions,Mn_(3-x)O_(4-y)@NCA exhibits an energy density of 37.5 W h kg^(-1)and an ultra-high power density of 563 W kg^(-1)in an asymmetric supercapacitor.In sodium-ion batteries,it demonstrates high reversible capacity and exceptional cycling stability.This research presents a new method to improve the Na^(+)storage performance in manganese-based oxide,which is expected to be generalized to other structural distortion.
基金the Natural Science Foundation of Shandong Province (ZR2021MB101,ZR2021ME113,ZR2021ME177,and ZR2021QE096)。
文摘The recent emergence of tetragonal phases zirconium dioxide(ZrO_(2))with vacancies has generated significant interest as a highly efficient and stable electrocatalyst with potential applications in trapping polysulfides and facilitating rapid conversion in lithium-sulfur batteries(LSBs).However,the reduction of ZrO_(2)is challenging,even under strong reducing atmospheres at high temperatures and pressures.Consequently,the limited presence of oxygen vacancies results in insufficient active sites and reaction interfaces,thereby hindering practical implementation.Herein,we successfully introduced abundant oxygen vacancies into ZrO_(2)at the nanoscale with the help of carbon nanotubes(CNTs-OH)through hydrogen-etching at lower temperatures and pressures.The introduced oxygen vacancies on ZrO_(2-x)/CNTs-OH can effectively rearrange charge distribution,enhance sulfiphilicity and increase active sites,contributing to high ionic and electronic transfer kinetics,strong binding energy and low redox barriers between polysulfides and ZrO_(2-x).These findings have been experimentally validated and supported by theory calculations.As a result,LSBs assembled with the ZrO_(2-x)/CNTs-OH modified separators demonstrate excellent rate performance,superior cycling stability,and ultra-high sulfur utilization.Especially,at high sulfur loading of 6 mg cm^(-2),the area capacity is still up to 6.3 mA h cm^(-2).This work provides valuable insights into the structural and functional optimization of electrocatalysts for batteries.
基金supported by the Key Research and Design Program of Qinhuangdao(202101A005)the Science and Technology Project of Hebei Education Department(QN2023094)+2 种基金the Cultivation Project for Basic Research and Innovation of Yanshan University(2021LGQN028)the Project for Research and Development of Metal Catalysts for Photo-thermal Decomposition of Waste Plastics to Prepare Value-added Chemicals(x2023322)the Subsidy for Hebei Key Laboratory of Applied Chemistry after Operation Performance(22567616H).
文摘Steam reforming of long-chain hydrocarbon fuels for hydrogen production has received great attention for thermal management of the hypersonic vehicle and fuel-cell application.In this work,Pt catalysts supported on CeO_(2)and Tb-doped CeO_(2)were prepared by a precipitation method.The physical structure and chemical properties of the as-prepared catalysts were characterized by powder X-ray diffraction,scanning electron microscopy,transmission electron microscopy,Raman spectroscopy,H_(2)temperature programmed reduction,and X-ray photoelectron spectroscopy.The results show that Tb-doped CeO_(2)supported Pt possesses abundant surface oxygen vacancies,good inhibition of ceria sintering,and strong metal-support interaction compared with CeO_(2)supported Pt.The catalytic performance of hydrogen production via steam reforming of long-chain hydrocarbon fuels(n-dodecane)was tested.Compared with 2Pt/CeO_(2),2Pt/Ce_(0.9)Tb_(0.1)O_(2),and 2Pt/Ce_(0.5)Tb_(0.5)O_(2),the 2Pt/Ce_(0.7)Tb_(0.3)O_(2)has higher activity and stability for hydrogen production,on which the conversion of n-dodecane was maintained at about 53.2%after 600 min reaction under 700℃at liquid space velocity of 9 ml·g^(-1)·h^(-1).2Pt/CeO_(2)rapidly deactivated,the conversion of n-dodecane was reduced to only 41.6%after 600 min.
基金This work was financially supported by the National Natural Science Foundation of China(Grant Nos.52173091,51973235)the Hubei Provincial Natural Science Foundation of China(Grant No.2021CFA022)Fundamental Research Funds for Central Universities(Grant No.CPT22023).
文摘Synergistic regulation of hierarchical nanostructures and defect engineering is effective in accelerating electron and ion transport for metal oxide electrodes.Herein,carbon nanofiber-supported V_(2)O_(3) with enriched oxygen vacancies(OV-V_(2)O_(3)@CNF)was fabricated using the facile electrospinning method,followed by thermal reduction.Differing from the traditional particles embedded within carbon nanofibers or irregularly distributed between carbon nanofibers,the free-standing OV-V_(2)O_(3)@CNF allows for V_(2)O_(3) nanosheets to grow vertically on one-dimensional(1D)carbon nanofibers,enabling abundant active sites,shortened ion diffusion pathway,continuous electron transport,and robust structural stability.Meanwhile,density functional theory calculations confirmed that the oxygen vacancies can promote intrinsic electron conductivity and reduce ion diffusion energy barrier.Consequently,the OV-V_(2)O_(3)@CNF anode delivers a large reversible capacity of 812 mAh g^(-1) at 0.1 A g^(-1),superior rate capability(405 mAh g^(-1) at 5 A g^(-1)),and long cycle life(378 mAh g^(-1) at 5 A g^(-1) after 1000 cycles).Moreover,an all-vanadium full battery(V2O5//OV-V_(2)O_(3)@CNF)was assembled using an OV-V_(2)O_(3)@CNF anode and a V2O5 cathode,which outputs a working voltage of 2.5 V with high energy density and power density,suggesting promising practical application.This work offers fresh perspectives on constructing hierarchical 1D nanofiber electrodes by combining defect engineering and electrospinning technology.
基金supported by the National Key Research and Development Program of China under Grant No.2023YFB3712401the National Natural Science Foundation of China under Grant Nos.12102254 and 12327802.
文摘The experimental results in previous studies have indicated that during the ductile fracture of pure metals,vacancies aggregate and form voids at grain boundaries.However,the physical mechanism underlying this phenomenon remains not fully understood.This study derives the equilibrium distribution of vacancies analytically by following thermodynamics and the micromechanics of crystal defects.This derivation suggests that vacancies cluster in regions under hydrostatic compression to minimize the elastic strain energy.Subsequently,a finite element model is developed for examining more general scenarios of interaction between vacancies and grain boundaries.This model is first verified and validated through comparison with some available analytical solutions,demonstrating consistency between finite element simulation results and analytical solutions within a specified numerical accuracy.A systematic numerical study is then conducted to investigate the mechanism that might govern the micromechanical interaction between grain boundaries and the profuse vacancies typically generated during plastic deformation.The simulation results indicate that the reduction in total elastic strain energy can indeed drive vacancies toward grain boundaries,potentially facilitating void nucleation in ductile fracture.
基金the National Natural Science Foundation of China(Nos.61973223,51972306)the Liao Ning Revitalization Talents Program(No.XLYC2007051)+2 种基金the Liaoning Educational Department Foundation(No.LJKMZ20220762,JYTMS20231510)the Natural Science Foundation of Liaoning Province(No.2023-MS-235,2023-MSLH-270)the Key Project in Science&Technology of SYUCT(No.2023DB005).
文摘Cu/ZnO is widely used in the hydrogenation of carbon dioxide (CO_(2)) to methanol (CH_(3)OH) to improve the lowconversion rate and selectivity generally observed. In this work, a series of In, Zr, Co, and Ni-doped CuO-ZnO catalysts wassynthesized via a hydrothermal method. By introducing a second metal element, the activity and dispersion of the activesites can be adjusted and the synergy between the metal and the carrier can be enhanced, forming an abundance of oxygenvacancies. Oxygen vacancies not only adsorb CO_(2) but also activate the intermediates in methanol synthesis, playing a keyrole in the entire reaction. Co3O4-CuO-ZnO had the best catalytic performance (a CO_(2) conversion rate of 9.17%;a CH_(3)OHselectivity of 92.77%). This study describes a typical strategy for multi-component doping to construct a catalyst with anabundance of oxygen vacancies, allowing more effective catalysis to synthesize CH_(3)OH from CO_(2).
基金supported by the BJAST High-level Innovation Team Program (No.BGS202001)the Beijing Postdoctoral Research Foundation (No.2022-ZZ-046)+3 种基金the National Natural and Science Foundation of China (No.51972026)the Japan Society for the Promotion of Science (JSPS)Grant-in-Aid for the Scientific Research (KAKENHI,Nos.16H06439 and 20H00297)the Dynamic Alliance for Open Innovations Bridging Human,Environment and Materials,the Cooperative Research Program of“Network Joint Research Center for Materials and Devices.”the scholarship granted to a visiting Ph.D.student of the Inter-University Exchange Project by the China Scholarship Council (CSC,No.201906460113)。
文摘The synthesis of oxygen vacancies(OVs)-modified TiO_(2)under mild conditions is attractive.In this work,OVs were easily introduced in TiO_(2)lattice during the hydrothermal doping process of trivalent iron ions.Theoretical calculations based on a novel charge-compensation structure model were employed with experimental methods to reveal the intrinsic photocatalytic mechanism of Fe-doped TiO_(2)(Fe-TiO_(2)).The OVs formation energy in Fe-TiO_(2)(1.12 eV)was only 23.6%of that in TiO_(2)(4.74 eV),explaining why Fe^(3+)doping could introduce OVs in the TiO_(2)lattice.The calculation results also indicated that impurity states introduced by Fe^(3+)and OVs enhanced the light absorption activity of TiO_(2).Additionally,charge carrier transport was investigated through the carrier lifetime and relative mass.The carrier lifetime of Fe-TiO_(2)(4.00,4.10,and 3.34 ns for 1at%,2at%,and 3at%doping contents,respectively)was longer than that of undoped TiO_(2)(3.22 ns),indicating that Fe^(3+) and OVs could promote charge carrier separation,which can be attributed to the larger relative effective mass of electrons and holes.Herein,Fe-TiO_(2)has higher photocatalytic indoor NO removal activity compared with other photocatalysts because it has strong light absorption activity and high carrier separation efficiency.
基金This work was supported by the National Natural Science Foundation of China (51973157,61904123)the Tianjin Natural Science Foundation (18JCQNJC02900)+3 种基金the Special Grade of the Financial Support from the China Postdoctoral Science Foundation (2020T130469)the Sci-ence and Technology Plans of Tianjin (19PTSYJC00010)the Science&Technol-ogy Development Fund of Tianjin Education Commission for Higher Education (2018KJ196)State Key Laboratory of Membrane and Membrane Separation,Tiangong University.
文摘Low-cost and flexible solid polymer electrolytes are promising in all-solid-state Li-metal batteries with high energy density and safety.However,both the low room-temperature ionic conductivities and the small Li^(+)transference number of these electrolytes significantly increase the internal resistance and overpotential of the battery.Here,we introduce Gd-doped CeO_(2) nanowires with large surface area and rich surface oxygen vacancies to the polymer electrolyte to increase the interaction between Gd-doped CeO_(2) nanowires and polymer electrolytes,which promotes the Li-salt dissociation and increases the concentration of mobile Li ions in the composite polymer electrolytes.The optimized composite polymer electrolyte has a high Li-ion conductivity of 5×10^(-4)4 S cm^(-1) at 30℃ and a large Li+transference number of 0.47.Moreover,the composite polymer electrolytes have excellent compatibility with the metallic lithium anode and high-voltage LiNi_(0.8)Mn _(0.1)Co_(0.1)O_(2)(NMC)cathode,providing the stable cycling of all-solid-state batteries at high current densities.
基金the National Natural Science Foundation of China(21902017)the Project of Fundamental Research and Frontier Exploration of Chongqing(cstc2019jcyj-msxmX0052)+5 种基金the Foundation of Technological Innovation and Application Development of Chongqing(cstc2021jscx-msxmX0308)the Key Projects of Technology Innovation and Application Development of Chongqing(cstc2019jscx-gksbX0022)the Banan Science and Technology Foundation of Chongqing(2018TJ03,2020QC374)the Major Project of Science and Technology Research Program of Chongqing Education Commission of China(KJZD-M202101101)the Youth Project of Science and Technology Research Program of Chongqing Education Commission of China(KJQN20211107)the Scientific Research Foundation of Chongqing University of Technology(2020ZDZ022)。
文摘Electrocatalytic CO_(2)reduction reaction to low-carbon alcohol is a challenging task,especially high selectivity for ethanol,which is mainly limited by the regulation of reaction intermediates and subsequent C–C coupling.A Cu-Co bimetallic catalyst with CN vacancies is successfully developed by H_(2)cold plasma toward a high-efficiency CO_(2)RR into low-carbon alcohol.The Cu-Co PBA-V_(CN)(Prussian blue analogues with CN vacancies)electrocatalyst yields methanol and ethanol as major products with a total low-carbon alcohol FE of 83.8%(methanol:39.2%,ethanol:44.6%)at-0.9 V vs.RHE,excellent durability(100 h)and a small onset potential of-0.21 V.ATR-SEIRAS(attenuated total internal reflection surface enhanced infrared absorption spectroscopy)and DFT(density functional theory)reveal that the steric hindrance of V_(CN)can enhance the CO generation from*COOH,and the C–C coupling can also be increased by CO spillover on uniformly dispersed Cu atoms.This work provides a strategy for the design and preparation of electrocatalysts for CO_(2)RR into low-carbon alcohol products and highlights the impact of catalyst steric hindrance to catalytic performance.
基金funding support by the National Natural Science Foundation of China(Grant No.21872116 and 22075232)the Mobility Program of the Sino-German Center for Research Promotion(Grant No.M-0377)the financial support by National Natural Science Foundation of China(Grant No.21991151,21991150,22021001)。
文摘Developing highly-active,earth-abundant non-precious-metal catalysts for hydrogen evolution reaction(HER)in alkaline solution would be beneficial to sustainable energy storage.Perovskite oxides are generally regarded as low-active HER catalysts,due to their inapposite hydrogen adsorption and water dissociation.Here,we report a detailed study on perovskite LaCoO_(3)epitaxial thin films as a model catalyst to significantly enhance the HER performance via an electrochemical activation process.As a result,the overpotential for the activation films to achieve a current density of 0.36 m A/cm^(2)is 238 m V,reduced by more than 200 m V in comparison with that of original samples.Structural characterization revealed the activation process dramatically increases the concentration of oxygen vacancies(Vo)on the surface of LaCoO_(3).We established the relationship between the electronic structure induced by Vo and the enhanced HER activity.Further theoretical calculations revealed that the Vo optimizes the hydrogen adsorption and dissociation of water on the surface of LaCoO_(3)thin films,thus improving the HER catalytic activity.This work may promote a deepened understanding of perovskite oxides for HER mechanism by Vo adjusting and a new avenue for designing highly active electrochemical catalysts in alkaline solution.
基金supported by the Natural Science Foundation of China(5207123251871165)。
文摘Understanding the crystal phase evolution of bimetallic oxide anodes is the main concern to profoundly reveal the conversion reaction kinetics and sodium-ion storage mechanisms.Herein,an integrated selfsupporting anode of the Cu-decorated Cu-Mn bimetallic oxides with oxygen vacancies(Ov-BMO-Cu)are in-situ generated by phase separation and hydrogen etching using nanoporous Cu-Mn alloy as selfsacrificial templates.On this basis,we have elucidated the relationship between the phase evolution,oxygen vacancies and sodium-ion storage mechanisms,further demonstrating the evolution of oxygen vacancies and the inhibition effect of manganese oxides as an“anchor”on grain aggregation of copper oxides.The kinetic analyses confirm that the expanded lattice space and increased oxygen vacancies of cycled Ov-BMO-Cu synergistically guarantee effective sodium-ion diffusion and storage mechanisms.Therefore,the Ov-BMO-Cu electrode exhibits higher reversible capacities of 4.04 mA h cm^(-2)at 0.2 mA cm^(-2)after 100 cycles and 2.20 m A h cm^(-2)at 1.0 mA cm^(-2)after 500 cycles.Besides,the presodiated Ov-BMO-Cu anode delivers a considerable reversible capacity of 0.79 m A h cm^(-2)at 1.0 mA cm^(-2)after 60 cycles in full cells with Na_(3)V_(2)(PO_(4))_(3)cathode,confirming its outstanding practicality.Thus,this work is expected to provide enlightenment for designing high-capacity bimetallic oxide anodes.
基金supported by the China Postdoctoral Science Foundation(Nos.2021M690534 and 2020M673650)the Science and Technology Research Program of Chongqing Municipal Education Commission(Nos.KJQN202101439 and KJQN202101441)+1 种基金the Innovation Research Team at Institutions of Higher Education in Chongqing(No.CXQT20027)the Program for Vanadium and Titanium Resource Comprehensive Utilization Key Laboratory of Sichuan Province(No.2022FTSZ02)。
文摘Achieving high-efficiency sodium storage in metal selenides is still severely constrained in consideration of their inferior electronic conductivity and inadequate Na^(+)insertion pathways and active sites.Heteroatom doping accompanied by spontaneously developed lattice defects can effectively tune electronic structure of metal selenides,which give a strong effect to motivate fast charge transfer and Na^(+)accessibility.Herein,we finely designed and successfully constructed a fascinating phosphorus-doped Cu_(2)Se@C hollow nanosphere with abundant vacancy defects(Cu_(2)P_(x)Se_(1-x)@C)through a combination strategy of selenization of Cu_(2)O nanosphere template,self-polymerization of dopamine,and subsequent phosphorization treatment.Such exquisite composite possesses enriched active sites,superior conductivity,and sufficient Na^(+)insertion channel,which enable much faster Na^(+)diffusion rates and more remarkable pseudocapacitive features,Satisfyingly,the Cu_(2)P_(x)Se_(1-x)@C composites manifest the supernormal sodium-storage capabilities,that is,a reversible capacity of 403.7 mA h g^(-1) at 1.0 A g^(-1) over 100 cycles,and an ultrastable cyclic lifespan over 1000 cycles at 20.0 A g^(-1) with a high capacity-retention of about249.7 mA h g^(-1).The phase transformation of the Cu_(2)P_(x)Se_(1-x)@C involving the intercalation of Na^(+)into Cu_(2)Se and the following conversion of NaCuSe to Cu and Na2Se were further demonstrated through a series of ex-situ characterization methods.DFT results demonstrate that the coexistence of phosphorusdoping and vacancy defects within Cu_(2)Se results in the reduction of Na^(+)adsorption energy from-1.47to-1.56 eV improving the conductivity of Cu_(2)Se to further accelerate fast Na^(+)mobility.
基金supported by the National Key Research and Development Program of China(2020YFA0715000)the National Natural Science Foundation of China(52127816)+2 种基金Foshan Xianhu Laboratory of the Advanced Energy Science and Technology Guangdong Laboratory(XHT2020-003)the China Postdoctoral Science Foundation(2021 M692490)the Fundamental Research Funds for the Central Universities(WUT:2020III029,2020IVA100).
文摘Rational design and construction of highly efficient nonprecious electrocatalysts for oxygen reduction and alcohols oxidation reactions(ORR,AOR)are extremely vital for the development of direct oxidation alkaline fuel cells,metal-air batteries,and water electrolysis system involving hydrogen and value-added organic products generation,but they remain a great challenge.Herein,a bifunctional electrocatalyst is prepared by anchoring CuS/NiS_(2)nanoparticles with abundant heterointerfaces and sulfur vacancies on graphene(Cu_(1)Ni_(2)-S/G)for ORR and AOR.Benefiting from the synergistic effects between strong interfacial coupling and regulation of the sulfur vacancies,Cu_(1)Ni_(2)-S/G achieves dramatically enhanced ORR activity with long term stability.Meanwhile,when ethanol is utilized as an oxidant for AOR,an ultralow potential(1.37 V)at a current density of 10 mA cm-2 is achieved,simultaneously delivering a high Faradaic efficiency of 96%for ethyl acetate production.Cu_(1)Ni_(2)-S/G also exhibits catalytic activity for other alcohols electrooxidation process,indicating its multifunctionality.This work not only highlights a viable strategy for tailoring catalytic activity through the synergetic combination of interfacial and vacancies engineering,but also opens up new avenues for the construction of a self-driven biomass electrocatalysis system for the generation of value-added organic products and hydrogen under ambient conditions.
基金supported by the National Natural Science Foundation of China (52200123, 22225606, 22261142663)。
文摘Surface oxygen vacancies(OVs) with abundant localized electrons on bismuth-oxygen based photocatalysts are proved to have the ability to capture and activate CO_(2).However,the surface OVs are easily filled with oxygen-containing species and destroyed,losing their effects as active sites and hindering the subsequent CO_(2)photoreduction.For realistic and sustainable CO_(2)photoreduction,constructing sustainable and stable surface OVs as active sites on photocatalysts is essential.This work shows the synthesis of interlayer stretched Bi_(2)O_(2)CO_(3) ultrathin nanosheets with tensile stress,which are beneficial to continuously generating light-induced dynamic OVs.With sufficient active sites,excellent,stable,and selective photoreduction of CO_(2)to CO under simulated solar light is achieved.The light-induced OVs can reduce the energy barrier of rate-determining step,resulting in the 100% product selectivity.The results presented herein demonstrate the effect of dynamic OVs induced by interlayer tensile strain on catalysts for the enhanced selective CO_(2)photoreduction process.
基金National Natural Science Foundation of China,Grant/Award Numbers:21875112,22109073Natural Science Foundation of Jiangsu Province,Grant/Award Number:BK20221321。
文摘Heteroatomic substitution and vacancy engineering of spinel oxides can theoretically optimize the oxygen evolution reaction(OER)through charge redistribution and d-band center modification but still remain a great challenge in both the preparation and catalytic mechanism.Herein,we proposed a novel and efficient Ar-plasma(P)-assisted strategy to construct heteroatom Mo-substituted and oxygen vacancies enriched hierarchical spinel Co_(3)O_(4)porous nanoneedle arrays in situ grown on carbon cloth(denoted P-Mo-Co_(3)O_(4)@CC)to improve the OER performance.Ar-plasma technology can efficiently generate vacancy sites at the surface of hydroxide,which induces the anchoring of Mo anion salts through electrostatic interaction,finally facilitating the substitution of Mo atoms and the formation of oxygen vacancies on the Co_(3)O_(4)surface.The P-Mo-Co_(3)O_(4)@CC affords a low overpotential of only 276 mV at 10 mA cm^(−2)for the OER,which is 58 mV superior to that of Mo-free Co_(3)O_(4)@CC and surpasses commercial RuO_(2)catalyst.The robust stability and satisfactory selectivity(nearly 100%Faradic efficiency)of P-Mo-Co_(3)O_(4)@CC for the OER are also demonstrated.Theoreti-cal studies demonstrate that Mo with variable valance states can efficiently regulates the atomic ratio of Co^(3+)/Co^(2+)and increases the number of oxygen vacancies,thereby inducing charge redistribution and tuning the d-band center of Co_(3)O_(4),which improve the adsorption energy of oxygen intermediates(e.g.,*OOH)on P-Mo-Co_(3)O_(4)@CC during OER.Furthermore,the two-electrode OER//HER electrolyzer equipped with P-Mo-Co_(3)O_(4)@CC as anode displays a low operation potential of 1.54 V to deliver a current density of 10 mA cm^(−2),and also exhibits good reversibility and anticurrent fluctuation ability under simulated real energy supply conditions,demonstrating the great potential of P-Mo-Co_(3)O_(4)@CC in water electrolysis.
基金supported by the National Natural Science Foundation of China under Grant Nos. 52072196, 52002200, 52102106 and 52002199Major Basic Research Program of the Natural Science Foundation of Shandong Province under Grant No. ZR2020ZD09+2 种基金the Natural Science Foundation of Shandong Province under Grant No. ZR2020QE063the Innovation and Technology Program of Shandong Province under Grant No. 2020KJA004the Taishan Scholars Program of Shandong Province under Grant No. ts201511034
文摘In recent years,manganese-based oxides as an advanced class of cathode materials for zinc-ion batteries(ZIBs)have attracted a great deal of attentions from numerous researchers.However,their slow reaction kinetics,limited active sites and poor electrical conductivity inevitably give rise to the severe performance degradation.To solve these problems,herein,we introduce abundant oxygen vacancies into the flower-likeδ-MnO_(2)nanostructure and effectively modulate the vacancy defects to reach the optimal level(δ-MnO_(2)-x-2.0).The smart design intrinsically tunes the electronic structure,guarantees ion chemisorption-desorption equilibrium and increases the electroactive sites,which not only effectively accelerates charge transfer rate during reaction processes,but also endows more redox reactions,as verified by first-principle calculations.These merits can help the fabricatedδ-MnO_(2)-x-2.0 cathode to present a large specific capacity of 551.8 mAh g^(-1) at 0.5 A g^(-1),high-rate capability of 262.2 mAh g^(-1) at 10 A g^(-1) and an excellent cycle lifespan(83%of capacity retention after 1500 cycles),which is far superior to those of the other metal compound cathodes.In addition,the charge/discharge mechanism of theδ-MnO_(2)-x-2.0 cathode has also been elaborated through ex situ techniques.This work opens up a new pathway for constructing the next-generation high-performance ZIBs cathode materials.
文摘The low-valence cations Na^(+)and Sr^(2+)were selected as the co-dopants to increase the vacancies concentration in the Y_(2.982)Ce_(0.018)Al_(2)Ga_(3)O_(12)phosphor.The successful incorporation of Na^(+)and Sr^(2+)was confirmed by the X-Ray Difiraction(XRD)results.All the samples show 5d-4f green persistent luminescence of Ce^(3+)after 450 nm excitation.The decay curves demonstrate that the persistent luminescence is efiectively enhanced with Na+and Sr2+doping.The thermoluminescence glow curves also show not only does the trap concentration increase,but also the distribution of trap depths is broadened.In addition,the air-and H_(2)/Ar-annealing treatments were conducted on every as-made sample.The experimental results prove that the increased traps after the Na^(+)/Sr^(2+)doping are mainly attributed to the oxygen vacancies,and the traps have a continuous and broad distribution of trap depths.We hope this work could give new inspiration for designing a high-performance persistent phosphor.
