The photocatalytic conversion of CO_(2)into solar‐powered fuels is viewed as a forward‐looking strategy to address energy scarcity and global warming.This work demonstrated the selective photoreduction of CO_(2)to C...The photocatalytic conversion of CO_(2)into solar‐powered fuels is viewed as a forward‐looking strategy to address energy scarcity and global warming.This work demonstrated the selective photoreduction of CO_(2)to CO using ultrathin Bi_(12)O_(17)Cl_(2)nanosheets decorated with hydrothermally synthesized bismuth clusters and oxygen vacancies(OVs).The characterizations revealed that the coexistences of OVs and Bi clusters generated in situ contributed to the high efficiency of CO_(2)–CO conversion(64.3μmol g^(−1)h^(−1))and perfect selectivity.The OVs on the facet(001)of the ultrathin Bi_(12)O_(17)Cl_(2)nanosheets serve as sites for CO_(2)adsorption and activation sites,capturing photoexcited electrons and prolonging light absorption due to defect states.In addition,the Bi‐cluster generated in situ offers the ability to trap holes and the surface plasmonic resonance effect.This study offers great potential for the construction of semiconductor hybrids as multiphotocatalysts,capable of being used for the elimination and conversion of CO_(2)in terms of energy and environment.展开更多
MgH_(2) is a promising high-capacity solid-state hydrogen storage material,while its application is greatly hindered by the high desorption temperature and sluggish kinetics.Herein,intertwined 2D oxygen vacancy-rich V...MgH_(2) is a promising high-capacity solid-state hydrogen storage material,while its application is greatly hindered by the high desorption temperature and sluggish kinetics.Herein,intertwined 2D oxygen vacancy-rich V_(2)O_(5) nanosheets(H-V_(2)O_(5))are specifically designed and used as catalysts to improve the hydrogen storage properties of MgH_(2).The as-prepared MgH_(2)-H-V_(2)O_(5) composites exhibit low desorption temperatures(Tonset=185℃)with a hydrogen capacity of 6.54 wt%,fast kinetics(Ea=84.55±1.37 kJ mol^(-1) H_(2) for desorption),and long cycling stability.Impressively,hydrogen absorption can be achieved at a temperature as low as 30℃ with a capacity of 2.38 wt%within 60 min.Moreover,the composites maintain a capacity retention rate of~99%after 100 cycles at 275℃.Experimental studies and theoretical calculations demonstrate that the in-situ formed VH_(2)/V catalysts,unique 2D structure of H-V_(2)O_(5) nanosheets,and abundant oxygen vacancies positively contribute to the improved hydrogen sorption properties.Notably,the existence of oxygen vacancies plays a double role,which could not only directly accelerate the hydrogen ab/de-sorption rate of MgH_(2),but also indirectly affect the activity of the catalytic phase VH_(2)/V,thereby further boosting the hydrogen storage performance of MgH_(2).This work highlights an oxygen vacancy excited“hydrogen pump”effect of VH_(2)/V on the hydrogen sorption of Mg/MgH_(2).The strategy developed here may pave a new way toward the development of oxygen vacancy-rich transition metal oxides catalyzed hydride systems.展开更多
The activation of H_(2)O is a key step of the COS hydrolysis,which may be tuned by oxygen vacancy defects in the catalysts.Herein,we have introduced Cu into Co_(3)O_(4) to regulate the oxygen vacancy defect content of...The activation of H_(2)O is a key step of the COS hydrolysis,which may be tuned by oxygen vacancy defects in the catalysts.Herein,we have introduced Cu into Co_(3)O_(4) to regulate the oxygen vacancy defect content of the catalysts.In situ DRIFTS and XPS spectra reveal that COS and H_(2)O are adsorbed and activated by oxygen vacancy.The 10 at%Cu doped Co_(3)O_(4) sample(10Cu-Co_(3)O_(4))exhibits the optimal activity,100%of COS conversion at 70℃.The improved oxygen vacancies of CueCo_(3)O_(4) accelerate the activation of H_(2)O to form active -OH.COS binds with hydroxyl to form the intermediate HSCO^(-)_(2),and then the activated-OH on the oxygen vacancy reacts with HSCO^(-)_(2) to form HCO^(-)_(3).Meanwhile,the catalyst exhibits high catalytic stability because copper species(Cu+/Cu^(2+))redox cycle mitigate the sulfation of Co_(3)O_(4)(Co^(2+)/Co^(3+)).Our work offers a promising approach for the rational design of cobalt-related catalysts in the highly efficient hydrolysis COS process.展开更多
The“shuttle effect”of lithium polysulfides(LiPSs)is a huge challenge for practical use of high-energydensity lithium-sulfur(Li-S)batteries,and one of the main reasons is the sluggish kinetics of sulfur conversion.Me...The“shuttle effect”of lithium polysulfides(LiPSs)is a huge challenge for practical use of high-energydensity lithium-sulfur(Li-S)batteries,and one of the main reasons is the sluggish kinetics of sulfur conversion.Metal oxides are able to expedite the sulfur electrochemistry,and the structural defects enhance the adsorption-conversion ability of metal oxides for polysulfides.However,a significant research gap still remains regarding the relationship between the oxygen vacancy concentration and the adsorptivecatalytic performance of metal oxides.Herein,we establish a correlation between oxygen vacancy concentration and adsorptive-catalytic properties by using tungsten oxide(WO_(x))as model catalysts.It is revealed that high-concentration oxygen vacancy is beneficial for enhancing the binding between tungsten oxide and LiPSs,reducing the energy barrier of Li_(2)S decomposition,and promoting polysulfide conversion kinetics.Consequently,the Li-S batteries using the tungsten oxide with high-concentration oxygen vacancies deliver high initial discharge capacity of 1169 mA h g^(-1)at 0.2 C and 865 mA h g^(-1)at 2 C,low attenuation rate of 0.064%per cycle over 1100 cycles at 2 C.With a high sulfur area loading of 5.34 mg cm^(-2),the Li-S batteries still exhibit high initial gravimetric capacity of 982 mA h g^(-1)at 0.1 C and areal capacity of 5.92 mA h cm^(-2).This work promotes the feasibility of defect engineering on metal oxides as an effective mean to enhance the practicality of Li-S batteries.展开更多
Lithium sulfur batteries have attracted much attention due to their high theoretical specific energy and environmental friendliness.However,the practical application is severely plagued by the cycling life issues resu...Lithium sulfur batteries have attracted much attention due to their high theoretical specific energy and environmental friendliness.However,the practical application is severely plagued by the cycling life issues resulting from the uncontrollable generation and growth of Li dendrites.Herein,an innovative 3D flexible self-supporting Li anode protection layer of P-Mn_(3)O_(4-x)is constructed via a facile solvothermal method followed by an annealing process.Benefiting from the rich oxygen vacancies coupled with the 3D flexible self-supporting skeleton,abundant lithiophilic sites and high ionic conductivity are obtained,which succeed in guiding Li+homogeneous adsorption and redistribution,accelerating Li+diffusion rate,inducing Li+uniform deposition and nucleation.DFT calculations and experimental results conclusively demonstrate such a protection mechanism.Meanwhile,the effective anchoring and catalytic nature of polar P-Mn_(3)O_(4-x)can also be applied as an immobilization-diffusion-conversion host to improve polysulfides redox.Taking advantage of these merits,super-stable functions for Li symmetric cell matched with P-Mn_(3)O_(4-x)layer are achieved,which exhibits an ultralong lifespan of>5000 h with an ultralow overpotential of 20 m V,far lower than that of bare Li symmetric cell(overpotential of 800 m V only after 250 h)at high current densities of 5 m A cm^(-2)and high plating/stripping capacity of 10 m A h cm^(-2).Even in Li|P-Mn_(3)O_(4-x)||S full cell at 1 C,a high initial discharge specific capacity of 843.1 m A h g^(-1)is still delivered with ultralow capacity fading rate of 0.07%per cycle after 250 cycles,further confirming the synergistic regulation of P-Mn_(3)O_(4-x)for Li nucleation behavior.This work illustrates a sufficient guarantee of 3D protection layer coupled with oxygen vacancies in guiding Li diffusion and nucleation behavior and provides new guidance for promoting the development of advanced Li-S batteries.展开更多
Rechargeable aluminum batteries(RABs)are attractive cadidates for next-generation energy storage and conversion,due to the low cost and high safety of Al resources,and high capacity of metal Al based on the three-elec...Rechargeable aluminum batteries(RABs)are attractive cadidates for next-generation energy storage and conversion,due to the low cost and high safety of Al resources,and high capacity of metal Al based on the three-electrons reaction mechanism.However,the development of RABs is greatly limited,because of the lack of advanced cathode materials,and their complicated and unclear reaction mechanisms.Exploring the novel nanostructured transition metal and carbon composites is an effective route for obtaining ideal cathode materials.In this work,we synthesize porous CoSnO_(3)/C nanocubes with oxygen vacancies for utilizing as cathodes in RABs for the first time.The intrinsic structure stability of the mixed metal cations and carbon coating can improve the cycling performance of cathodes by regulating the internal strains of the electrodes during volume expansion.The nanocubes with porous structures contribute to fast mass transportation which improves the rate capability.In addition to this,abundant oxygen vacancies promote the adsorption affinity of cathodes,which improves storage capacity.As a result,the CoSnO_(3)/C cathodes display an excellent reversible capacity of 292.1 mAh g^(-1) at 0.1 A g^(-1),a good rate performance with 109 mAh g^(-1) that is maintained even at 1 A g^(-1) and the provided stable cycling behavior for 500 cycles.Besides,a mechanism of intercalation of Al^(3+)within CoSnO_(3)/C cathode is proposed for the electrochemical process.Overall,this work provides a step toward the development of advanced cathode materials for RABs by engineering novel nanostructured mixed transition-metal oxides with carbon composite and proposes novel insights into chemistry for RABs.展开更多
Electron transport layer(ETL)is pivotal to charge carrier transport for PSCs to reach the Shockley-Queisser limit.This study provides a fundamental understanding of heterojunction electron transport layers(ETLs)at the...Electron transport layer(ETL)is pivotal to charge carrier transport for PSCs to reach the Shockley-Queisser limit.This study provides a fundamental understanding of heterojunction electron transport layers(ETLs)at the atomic level for stable and efficient perovskite solar cells(PSCs).The bilayer structure of an ETL composed of SnO_(2) on TiO_(2) was examined,revealing a critical factor limiting its potential to obtain efficient performance.Alteration of oxygen vacancies in the TiO_(2) underlayer via an annealing process is found to induce manipulated band offsets at the interface between the TiO_(2) and SnO_(2) layers.In-depth electronic investigations of the bilayer structure elucidate the importance of the electronic properties at the interface between the TiO_(2) and SnO_(2) layers.The apparent correlation in hysteresis phenomena,including current density-voltage(J-V)curves,appears as a function of the type of band alignment.Density functional theory calculations reveal the intimate relationship between oxygen vacancies,deep trap states,and charge transport efficiency at the interface between the TiO_(2) and SnO_(2) layers.The formation of cascade band alignment via control over the TiO_(2) underlayer enhances device performance and suppresses hysteresis.Optimal performance exhibits a power conversion efficiency(PCE)of 23.45%with an open-circuit voltage(V_(oc))of 1.184 V,showing better device stability under maximum power point tracking compared with a staggered bilayer under one-sun continuous illumination.展开更多
Oxygen vacancy formation and migration in La0.9Sr0.1Ga0.8Mg0.2O3-5 （LSGM） with various crystal symmetries （cubic, rhombohedral, orthorhombic, and monoclinic） are studied by employing first-principles calculations ...Oxygen vacancy formation and migration in La0.9Sr0.1Ga0.8Mg0.2O3-5 （LSGM） with various crystal symmetries （cubic, rhombohedral, orthorhombic, and monoclinic） are studied by employing first-principles calculations based on density functional theory （DFT）. It is shown that the cubic LSGM has the smallest band gap, oxygen vacancy formation energy, and migration barrier, while the other three structures give rise to much larger values for these quantities, implying the best oxygen ion conductivity of the cubic LSGM among the four crystal structures. In out calculations, one oxygen vacancy migration pathway is considered in the cubic and rhombohedral structures due to all the oxygen sites being equivalent in them, while two vacancy migration pathways with different migration barriers are found in the orthorhombic and monoclinic symmetries owing to the existence of nonequivalent O1 and 02 oxygen sites. The migration energies along the migration pathway linking the two 02 sites are obviously lower than those along the pathway linking the O1 and 02 sites. Considering the phase transitions at high temperatures, the results obtained in this paper can not only explain the experimentally observed different behaviours of the oxygen ionic conductivity of LSGM with different symmetries, but also predict the rational crystal structures of LSGM for solid oxide fuel cell applications.展开更多
Oxygen vacancy （Ov） has significant influence on physical and chemical properties of TiO2 systems, especially on surface catalytic processes. In this work, we investigate the effects of Ov on the adsorption of forma...Oxygen vacancy （Ov） has significant influence on physical and chemical properties of TiO2 systems, especially on surface catalytic processes. In this work, we investigate the effects of Ov on the adsorption of formaldehyde （HCHO） on TiO2（110） surfaces through first- principles calculations. With the existence of Ov, we find the spatial distribution of surface excess charge can change the relative stability of various adsorption configurations. In this case, the bidentate adsorption at five-coordinated Ti （Tisc） can be less stable than the monodentate adsorption. And HCHO adsorbed in Ov becomes the most stable structure. These results are in good agreement with experimental observations, which reconcile the long-standing deviation between the theoretical prediction and experimental results. This work brings insights into how the excess charge affects the molecule adsorption on metal oxide surface.展开更多
Doping with various impurities is an effective approach to improve the photoelectrochemical properties of TiO2. Here, we explore the effect of oxygen vacancy on geometric and elec- tronic properties of compensated （i...Doping with various impurities is an effective approach to improve the photoelectrochemical properties of TiO2. Here, we explore the effect of oxygen vacancy on geometric and elec- tronic properties of compensated （i.e. V-N and Cr-C） and non-compensated （i.e. V-C and Cr-N） codoped anatase TiO2 by performing extensive density functional theory calculations. Theoretical results show that oxygen vacancy prefers to the neighboring site of metal dopant （i.e. V or Cr atom）. After introduction of oxygen vacancy, the unoccupied impurity bands located within band gap of these codoped TiO2 will be filled with electrons, and the posi- tion of conduction band offset does not change obviously, which result in the reduction of photoinduced carrier recombination and the good performance for hydrogen production via water splitting. Moreover, we find that oxygen vacancy is easily introduced in V-N codoped TiO2 under O-poor condition. These theoretical insights are helpful for designing codoped TiO2 with high photoelectrochemical performance.展开更多
Bi2MoO6,a typical Bi-based photocatalyst,has received increasing interests and been widely applied in various fields.However,the visible light photocatalytic activity of Bi2MoO6 is still restricted by some obstacles,s...Bi2MoO6,a typical Bi-based photocatalyst,has received increasing interests and been widely applied in various fields.However,the visible light photocatalytic activity of Bi2MoO6 is still restricted by some obstacles,such as limited photo-response and low charge separation efficiency.In this work,we developed a facile method to introduce artificial oxygen vacancy into Bi2MoO6 microspheres,which could effectively address these problems and realize highly efficient visible light photocatalysis.The experimental and theoretical methods were combined to explore the effects of oxygen vacancy on the electronic structure,photocatalytic activity and the reaction mechanism toward NO removal.The results showed that the addition of NaBH4 during catalyst preparation induced the formation of oxygen vacancy in Bi2MoO6,which plays a significant role in extending the visible light absorption of Bi2MoO6.The visible light photocatalytic activity of Bi2MoO6 with oxygen vacancy was obviously enhanced with a NO removal ratio of 43.5%,in contrast to that of 25.0%with the pristine Bi2MoO6.This can be attributed to the oxygen vacancy that creates a defect energy level in the band gap of Bi2MoO6,thus facilitating the charge separation and transfer processes.Hence,more reactive radicals were generated and participated in the photocatalytic NO oxidation reaction.The in situ FT-IR was used to dynamically monitor the photocatalytic NO oxidation process.The reaction intermediates were observed and the adsorption-reaction mechanism was proposed.It was found that the reaction mechanism was unchanged by introducing the oxygen vacancy in Bi2MoO6.This work could provide new insights into the understanding of the oxygen vacancy in photocatalysis and gas-phase photocatalytic reaction mechanism.展开更多
To search the new effective nitrogen reduction reaction(NRR)electrocatalyst is very important for the ammonia-based industry.Herein,we reported the design of a novel NRR electrocatalyst with Ru NPs loaded on oxygen-va...To search the new effective nitrogen reduction reaction(NRR)electrocatalyst is very important for the ammonia-based industry.Herein,we reported the design of a novel NRR electrocatalyst with Ru NPs loaded on oxygen-vacancy TiO2(Ru/TiO2-Vo).Structural characterizations revealed that oxygen vacancy was loaded in the matrix of Ru/TiO2-Vo.Electrocatalytic results indicated that Ru/TiO2-Vo showed good NRR performance(2.11μg h^-1 cm^-2).Contrast tests showed that NRR property of Ru/TiO2-Vo was much better than those of Ru/TiO-12(B)(0.53μg hcm^-2)and Ru/P25(0.42μg h^-1 cm^-2).Furthermore,density functional theory calculation results indicated catalytic mechanism of NRR and rate-determining step(*N2+1/2 H2→*N+*NH)was the potential-determining step with the overpotential requirement of 0.21 V.A combination of electronic structure analysis and catalytic measurement shed light on the synergistic effect of Ru and oxygen vacancy on the NRR performance.展开更多
Surface defect modulation has emerged as a potential strategy for promoting the photocatalytic activity of photocatalysts for various applications, while the impact of the oxygen vacancy on bacterial inactivation is s...Surface defect modulation has emerged as a potential strategy for promoting the photocatalytic activity of photocatalysts for various applications, while the impact of the oxygen vacancy on bacterial inactivation is still debated. In this study, oxygen vacancies were introduced to tungsten trioxide nanosheets(WO3–x) via a microwave-assisted route. The as-prepared WO3–x nanosheets exhibited excellent visible-light-driven photocatalytic activity toward E. coli K-12 inactivation, and 6 log orders of the bacterial cells could be completely inactivated within 150 min. The obtained bacterial inactivation rate constant was 15.2 times higher than that of pristine WO3 without oxygen vacancies, suggesting that the surface oxygen vacancy could significantly promote the bacterial inactivation efficiency. The mechanism study indicated that the inactivation of bacterial cells occurs via a direct h+ oxidation pathway. In addition, the role of the oxygen vacancy was studied in detail;the oxygen vacancy was found to not only promote interfacial charge separation but also tune the band structure of WO3, thereby leading to increased h+ oxidation power. Finally, a possible oxygen vacancy-dominated photocatalytic bacterial inactivation mechanism is proposed. This work is expected to offer new insights into the microwave-assisted synthesis of defective photocatalysts and the use of the oxygen vacancy for promoting photocatalytic antibacterial activities.展开更多
Photocatalytic degradation of gaseous pollutants on Bi-based semiconductors under solar lightirradiation has attracted significant attention.However,their application in gaseous straight-chainalkane purification is st...Photocatalytic degradation of gaseous pollutants on Bi-based semiconductors under solar lightirradiation has attracted significant attention.However,their application in gaseous straight-chainalkane purification is still rare.Here,a series of Bi/BiOBr composites were solvothermally synthe-sized and applied in solar-light-driven photocatalytic degradation of gaseous n-hexane.The charac-terization results revealed that both increasing number of functional groups of alcohol solvent(from methanol and ethylene glycol to glycerol)and solvothermal temperature(from 160 and 180to 200℃)facilitated the in-situ formation of metallic Bi nanospheres on BiOBr nanoplates withexposed(110)facets.Meanwhile,chemical bonding between Bi and BiOBr was observed on theseexposed facets that resulted in the formation of surface oxygen vacancy.Furthermore,the synergis-tic effect of optimum surface oxygen vacancy on exposed(110)facets led to a high visible light re-sponse,narrow band gap,great photocurrent,low recombination rate of the charge carriers,andstrong·O2-and h*formation,all of which resulted in the highest removal efficiency of 97.4%within120 min of 15 ppmv of n-hexane on Bi/BiOBr.Our findings efficiently broaden the application ofBi-based photocatalysis technology in the purification of gaseous straight-chain pollutants emittedby the petrochemical industry.展开更多
Oxygen vacancy plays vital roles in regulating the electronic and charge distribution of the oxygen deficient materials.Herein,abundant oxygen vacancies are created during assembling the two-dimensional(2D)ultra-thin ...Oxygen vacancy plays vital roles in regulating the electronic and charge distribution of the oxygen deficient materials.Herein,abundant oxygen vacancies are created during assembling the two-dimensional(2D)ultra-thin Bi_(2)MoO_(6) nanoflakes into three dimensional(3D)Bi_(2)MoO_(6) nanospheres,resulting in significantly improved performance for photocatalytical conversion of CO_(2) into liquid hydrocarbons.The increased performance is contributed by two primary sites,namely the abundant oxygen vacancy and the exposed molybdenum(Mo)atom induced by oxygen-migration,as revealed by the theoretical calculation.The oxygen vacancy(Ov)and uncovered Mo atom serving as dual binding sites for trapping CO_(2) molecules render the synchronous fixation-reduction process,resulting in the decline of activation energy for CO_(2) reduction from 2.15 eV on bulk Bi_(2)MoO_(6) to 1.42 eV on Ov-rich Bi_(2)MoO_(6).Such a striking decrease in the activation energy induces the efficient selective generation of liquid hydrocarbons,especially the methanol(C_(2)H_(5) OH)and ethanol(CH_(3) OH).The yields of CH_(3) OH and C_(2)H_(5) OH over the optimal Ov-Bi_(2)MoO_(6) is high up to 106.5 and 10.3μmol g^(-1) respectively,greatly outperforming that on the Bulk-Bi_(2)MoO_(6).展开更多
Oxygen vacancies(Vo)in electrocatalysts are closely correlated with the hydrogen evo-lution reaction(HER)activity.The role of vacancy defects and the effect of their concentration,how-ever,yet remains unclear.Herein,B...Oxygen vacancies(Vo)in electrocatalysts are closely correlated with the hydrogen evo-lution reaction(HER)activity.The role of vacancy defects and the effect of their concentration,how-ever,yet remains unclear.Herein,Bi2O3,an unfavorable electrocata-lyst for the HER due to a less than ideal hydrogen adsorption Gibbs free energy(ΔGH*),is utilized as a perfect model to explore the func-tion of Vo on HER performance.Through a facile plasma irradia-tion strategy,Bi2O3 nanosheets with different Vo concentrations are fabricated to evaluate the influence of defects on the HER process.Unexpectedly,while the generated oxygen vacancies contribute to the enhanced HER performance,higher Vo concentrations beyond a saturation value result in a significant drop in HER activity.By tunning the Vo concentration in the Bi_(2)O_(3)nanosheets via adjusting the treatment time,the Bi2O3 catalyst with an optimized oxygen vacancy concentration and detectable charge carrier concentration of 1.52×10^(24)cm^(−3)demonstrates enhanced HER performance with an overpotential of 174.2 mV to reach 10 mA cm^(−2),a Tafel slope of 80 mV dec−1,and an exchange current density of 316 mA cm−2 in an alkaline solution,which approaches the top-tier activity among Bi-based HER electrocatalysts.Density-functional theory calculations confirm the preferred adsorption of H*onto Bi2O3 as a function of oxygen chemical potential(ΔμO)and oxygen partial potential(PO2)and reveal that high Vo concentrations result in excessive stability of adsorbed hydrogen and hence the inferior HER activity.This study reveals the oxygen vacancy concentration-HER catalytic activity relationship and provides insights into activating catalytically inert materials into highly efficient electrocatalysts.展开更多
Indium oxide supported nickel catalyst has been experimentally confirmed to be highly active for CO_(2) hydrogenation towards methanol.In this work,the reaction mechanism for CO_(2) hydrogenation to methanol has been ...Indium oxide supported nickel catalyst has been experimentally confirmed to be highly active for CO_(2) hydrogenation towards methanol.In this work,the reaction mechanism for CO_(2) hydrogenation to methanol has been investigated on a model Ni/In_(2)O_(3) catalyst,i.e.,Ni_(4)/In_(2)O_(3),via the density functional theory(DFT)study.Three possible reaction pathways,i.e.,the formate pathway,CO hydrogenation and the reverse water-gas-shift(RWGS)pathways,have been examined on this model catalyst.It has been demonstrated that the RWGS pathway is the most theoretically-favored for CO_(2) hydrogenation to methanol.The complete RWGS pathway follows CO_(2)+6 H→COOH+5 H→CO+H_(2)O+4 H→HCO+H_(2)O+3 H→H_(2)CO+H_(2)O+2 H→H_(3)CO+H_(2)O+H→H_(3)COH+H_(2) O.Furthermore,it has been also proved that the interfacial oxygen vacancy can serve as the active site for boosting the CO_(2) adsorption and charge transfer between the nickel species and indium oxide,which synergistically promotes the consecutive CO_(2) hydrogenation towards methanol.展开更多
Although sodium ion capacitors(SICs)are considered as one of the most promising electrochemical energy storage devices(organic electrolyte batteries,aqueous batteries and supercapacitor,etc.)due to the combined merits...Although sodium ion capacitors(SICs)are considered as one of the most promising electrochemical energy storage devices(organic electrolyte batteries,aqueous batteries and supercapacitor,etc.)due to the combined merits of battery and capacitor,the slow reaction kinetics and low specific capacity of anode materials are the main challenges.Point defects including vacancies and heteroatoms doping have been widely used to improve the kinetics behavior and capacity of anode materials.However,the interaction between vacancies and heteroatoms doping have been seldomly investigated.In this study,a hybrid point defects(HPD)engineering has been proposed to synthesize TiO_(2) with both oxygen vacancies(OVs)and P-dopants(TiO_(2)/C-HPD).In comparison with sole OVs or P-doping treatments,the synergistic effects of HPD on its electrical conductivity and sodium storage performance have been clarified through the density func-tional theory calculation and sodium storage characterization.As expected,the kinetics and electronic conductivity of TiO_(2)/C-HPD3 are significantly improved,resulting in excellent rate performance and outstanding cycle stability.Moreover,the SICs assembled from TiO_(2)/C-HPD3 anode and nitrogen-doped porous carbon cathode show outstanding power/energy density,ultra-long life with good capacity retention.This work provides a novel point defect engineering perspective for the development of high-performance SICs electrode materials.展开更多
Despite the tremendous efforts devoted to enhancing the activity of oxygen evolution reaction(OER)catalysts,there is still a huge challenge to deeply understand the electronic structure characteristics of transition m...Despite the tremendous efforts devoted to enhancing the activity of oxygen evolution reaction(OER)catalysts,there is still a huge challenge to deeply understand the electronic structure characteristics of transition metal oxide to guide the design of more active catalysts.Herein,Fe_(3)O_(4)with oxygen vacancies(Fe_(3)O_(4)-Vac)was synthesized via Ar ion irradiation method and its OER activity was greatly improved by properly modulating the electron density around Fe atoms.The electron density of Fe_(3)O_(4)-Vac around Fe atoms increased compared to that of Fe_(3)O_(4)according to the characterization of synchrotron-based X-ray absorption near-edge structure(XANES),extended X-ray absorption fine structure(EXAFS)spectra,and density functional theory(DFT)calculation.Moreover,the DFT results indicate the enhancement of the desorption of HOO^(*)groups which significantly reduced the OER reaction barrier.Fe_(3)O_(4)-Vac catalyst shows an overpotential of 353 m V,lower than that of Fe OOH(853 m V)and Fe_(3)O_(4)(415 m V)at 10 m A cm^(-2),and a low Tafel slope of 50 m V dec^(-1)in 1 M KOH,which was even better than commercial RuO_(2)at high potential.This modulation approach provides us with valuable insights for exploring efficient and robust water-splitting electrocatalysts.展开更多
The SnO2-x. with different oxygen vacancy concentrations was modified by addling Sm. The modified SnO2-x was investigated by means of X-ray diffraction, X-ray photoelectron spectroscope, and scanning electron microsco...The SnO2-x. with different oxygen vacancy concentrations was modified by addling Sm. The modified SnO2-x was investigated by means of X-ray diffraction, X-ray photoelectron spectroscope, and scanning electron microscopy. Its gas-sensing properties to C2H6, C6H14, C2H5OH, CO, and H2 were studied too. The experiment results show that the gas-sensing properties of Sm/SnO2-x depend upon the amount of oxygen vacancies, therefore it is possible to improve gas-sensing properties of doped SnO2 by controlling its concentration of oxygen vacancy.展开更多
基金Natural Science Foundation of Shandong Province,Grant/Award Number:ZR2022MB106national training program of innovation and entrepreneurship for undergraduates,Grant/Award Number:202210424099National Natural Science Foundation of China,Grant/Award Numbers:21601067,21701057,21905147。
文摘The photocatalytic conversion of CO_(2)into solar‐powered fuels is viewed as a forward‐looking strategy to address energy scarcity and global warming.This work demonstrated the selective photoreduction of CO_(2)to CO using ultrathin Bi_(12)O_(17)Cl_(2)nanosheets decorated with hydrothermally synthesized bismuth clusters and oxygen vacancies(OVs).The characterizations revealed that the coexistences of OVs and Bi clusters generated in situ contributed to the high efficiency of CO_(2)–CO conversion(64.3μmol g^(−1)h^(−1))and perfect selectivity.The OVs on the facet(001)of the ultrathin Bi_(12)O_(17)Cl_(2)nanosheets serve as sites for CO_(2)adsorption and activation sites,capturing photoexcited electrons and prolonging light absorption due to defect states.In addition,the Bi‐cluster generated in situ offers the ability to trap holes and the surface plasmonic resonance effect.This study offers great potential for the construction of semiconductor hybrids as multiphotocatalysts,capable of being used for the elimination and conversion of CO_(2)in terms of energy and environment.
基金the support from the National Key Research&Development Program(2022YFB3803700)of ChinaNational Natural Science Foundation(No.52171186)the financial support from the Center of Hydrogen Science,Shanghai Jiao Tong University。
文摘MgH_(2) is a promising high-capacity solid-state hydrogen storage material,while its application is greatly hindered by the high desorption temperature and sluggish kinetics.Herein,intertwined 2D oxygen vacancy-rich V_(2)O_(5) nanosheets(H-V_(2)O_(5))are specifically designed and used as catalysts to improve the hydrogen storage properties of MgH_(2).The as-prepared MgH_(2)-H-V_(2)O_(5) composites exhibit low desorption temperatures(Tonset=185℃)with a hydrogen capacity of 6.54 wt%,fast kinetics(Ea=84.55±1.37 kJ mol^(-1) H_(2) for desorption),and long cycling stability.Impressively,hydrogen absorption can be achieved at a temperature as low as 30℃ with a capacity of 2.38 wt%within 60 min.Moreover,the composites maintain a capacity retention rate of~99%after 100 cycles at 275℃.Experimental studies and theoretical calculations demonstrate that the in-situ formed VH_(2)/V catalysts,unique 2D structure of H-V_(2)O_(5) nanosheets,and abundant oxygen vacancies positively contribute to the improved hydrogen sorption properties.Notably,the existence of oxygen vacancies plays a double role,which could not only directly accelerate the hydrogen ab/de-sorption rate of MgH_(2),but also indirectly affect the activity of the catalytic phase VH_(2)/V,thereby further boosting the hydrogen storage performance of MgH_(2).This work highlights an oxygen vacancy excited“hydrogen pump”effect of VH_(2)/V on the hydrogen sorption of Mg/MgH_(2).The strategy developed here may pave a new way toward the development of oxygen vacancy-rich transition metal oxides catalyzed hydride systems.
基金the National Natural Science Foundation of China (92034301,22078063 and 22022804)Major Program of Qingyuan Innovation Laboratory (00121003)the Natural Science Foundation of Fujian Province (2020H6007)。
文摘The activation of H_(2)O is a key step of the COS hydrolysis,which may be tuned by oxygen vacancy defects in the catalysts.Herein,we have introduced Cu into Co_(3)O_(4) to regulate the oxygen vacancy defect content of the catalysts.In situ DRIFTS and XPS spectra reveal that COS and H_(2)O are adsorbed and activated by oxygen vacancy.The 10 at%Cu doped Co_(3)O_(4) sample(10Cu-Co_(3)O_(4))exhibits the optimal activity,100%of COS conversion at 70℃.The improved oxygen vacancies of CueCo_(3)O_(4) accelerate the activation of H_(2)O to form active -OH.COS binds with hydroxyl to form the intermediate HSCO^(-)_(2),and then the activated-OH on the oxygen vacancy reacts with HSCO^(-)_(2) to form HCO^(-)_(3).Meanwhile,the catalyst exhibits high catalytic stability because copper species(Cu+/Cu^(2+))redox cycle mitigate the sulfation of Co_(3)O_(4)(Co^(2+)/Co^(3+)).Our work offers a promising approach for the rational design of cobalt-related catalysts in the highly efficient hydrolysis COS process.
基金financially supported by National Natural Science Foundation of China(Grant Nos.51972070 and 52062004)Guizhou Provincial High Level Innovative Talents Project(Grant No.QKHPTRC-GCC[2022]013-1)+2 种基金Innovation Team for Advanced Electrochemical Energy Storage Devices and Key Materials of Guizhou Provincial Higher Education Institutions(Grant No.QianJiaoJi[2023]054)Guizhou Provincial Science and Technology Projects(Grant No.QKHJC[2020]1Z042)Cultivation Project of Guizhou University(Grant No.GDPY[2019]01)。
文摘The“shuttle effect”of lithium polysulfides(LiPSs)is a huge challenge for practical use of high-energydensity lithium-sulfur(Li-S)batteries,and one of the main reasons is the sluggish kinetics of sulfur conversion.Metal oxides are able to expedite the sulfur electrochemistry,and the structural defects enhance the adsorption-conversion ability of metal oxides for polysulfides.However,a significant research gap still remains regarding the relationship between the oxygen vacancy concentration and the adsorptivecatalytic performance of metal oxides.Herein,we establish a correlation between oxygen vacancy concentration and adsorptive-catalytic properties by using tungsten oxide(WO_(x))as model catalysts.It is revealed that high-concentration oxygen vacancy is beneficial for enhancing the binding between tungsten oxide and LiPSs,reducing the energy barrier of Li_(2)S decomposition,and promoting polysulfide conversion kinetics.Consequently,the Li-S batteries using the tungsten oxide with high-concentration oxygen vacancies deliver high initial discharge capacity of 1169 mA h g^(-1)at 0.2 C and 865 mA h g^(-1)at 2 C,low attenuation rate of 0.064%per cycle over 1100 cycles at 2 C.With a high sulfur area loading of 5.34 mg cm^(-2),the Li-S batteries still exhibit high initial gravimetric capacity of 982 mA h g^(-1)at 0.1 C and areal capacity of 5.92 mA h cm^(-2).This work promotes the feasibility of defect engineering on metal oxides as an effective mean to enhance the practicality of Li-S batteries.
基金supported by the Natural Science Foundation of Shandong Province(ZR2021MB101,ZR2021ME113,ZR2021ME177,and ZR2021QE096)。
文摘Lithium sulfur batteries have attracted much attention due to their high theoretical specific energy and environmental friendliness.However,the practical application is severely plagued by the cycling life issues resulting from the uncontrollable generation and growth of Li dendrites.Herein,an innovative 3D flexible self-supporting Li anode protection layer of P-Mn_(3)O_(4-x)is constructed via a facile solvothermal method followed by an annealing process.Benefiting from the rich oxygen vacancies coupled with the 3D flexible self-supporting skeleton,abundant lithiophilic sites and high ionic conductivity are obtained,which succeed in guiding Li+homogeneous adsorption and redistribution,accelerating Li+diffusion rate,inducing Li+uniform deposition and nucleation.DFT calculations and experimental results conclusively demonstrate such a protection mechanism.Meanwhile,the effective anchoring and catalytic nature of polar P-Mn_(3)O_(4-x)can also be applied as an immobilization-diffusion-conversion host to improve polysulfides redox.Taking advantage of these merits,super-stable functions for Li symmetric cell matched with P-Mn_(3)O_(4-x)layer are achieved,which exhibits an ultralong lifespan of>5000 h with an ultralow overpotential of 20 m V,far lower than that of bare Li symmetric cell(overpotential of 800 m V only after 250 h)at high current densities of 5 m A cm^(-2)and high plating/stripping capacity of 10 m A h cm^(-2).Even in Li|P-Mn_(3)O_(4-x)||S full cell at 1 C,a high initial discharge specific capacity of 843.1 m A h g^(-1)is still delivered with ultralow capacity fading rate of 0.07%per cycle after 250 cycles,further confirming the synergistic regulation of P-Mn_(3)O_(4-x)for Li nucleation behavior.This work illustrates a sufficient guarantee of 3D protection layer coupled with oxygen vacancies in guiding Li diffusion and nucleation behavior and provides new guidance for promoting the development of advanced Li-S batteries.
基金supported by the National Natural Science Foundation of China (Grant No.22075028).
文摘Rechargeable aluminum batteries(RABs)are attractive cadidates for next-generation energy storage and conversion,due to the low cost and high safety of Al resources,and high capacity of metal Al based on the three-electrons reaction mechanism.However,the development of RABs is greatly limited,because of the lack of advanced cathode materials,and their complicated and unclear reaction mechanisms.Exploring the novel nanostructured transition metal and carbon composites is an effective route for obtaining ideal cathode materials.In this work,we synthesize porous CoSnO_(3)/C nanocubes with oxygen vacancies for utilizing as cathodes in RABs for the first time.The intrinsic structure stability of the mixed metal cations and carbon coating can improve the cycling performance of cathodes by regulating the internal strains of the electrodes during volume expansion.The nanocubes with porous structures contribute to fast mass transportation which improves the rate capability.In addition to this,abundant oxygen vacancies promote the adsorption affinity of cathodes,which improves storage capacity.As a result,the CoSnO_(3)/C cathodes display an excellent reversible capacity of 292.1 mAh g^(-1) at 0.1 A g^(-1),a good rate performance with 109 mAh g^(-1) that is maintained even at 1 A g^(-1) and the provided stable cycling behavior for 500 cycles.Besides,a mechanism of intercalation of Al^(3+)within CoSnO_(3)/C cathode is proposed for the electrochemical process.Overall,this work provides a step toward the development of advanced cathode materials for RABs by engineering novel nanostructured mixed transition-metal oxides with carbon composite and proposes novel insights into chemistry for RABs.
基金supported by the New&Renewable Energy Core Technology Program of the Korea Institute of Energy Technology Evaluation and Planning(KETEP)granted financial resource from the Ministry of Trade,Industry&Energy(MOTIE),Republic of Korea(No.20213091010020)National Research Foundation of Korea(NRF)grant funded by the Korea Government(MSIT)(2020R1A2C1101085)+2 种基金the Korea Institute of Planning and Evaluation for Technology in Food,Agriculture and Forestry(IPET)and Korea Smart Farm R&D Foundation(KosFarm)through Smart Farm Innovation Technology Development Programfunded by the Ministry of Agriculture,Food and Rural Affairs(MAFRA)the Ministry of Science and ICT(MSIT),Rural Development Administration(RDA)(421036-03).
文摘Electron transport layer(ETL)is pivotal to charge carrier transport for PSCs to reach the Shockley-Queisser limit.This study provides a fundamental understanding of heterojunction electron transport layers(ETLs)at the atomic level for stable and efficient perovskite solar cells(PSCs).The bilayer structure of an ETL composed of SnO_(2) on TiO_(2) was examined,revealing a critical factor limiting its potential to obtain efficient performance.Alteration of oxygen vacancies in the TiO_(2) underlayer via an annealing process is found to induce manipulated band offsets at the interface between the TiO_(2) and SnO_(2) layers.In-depth electronic investigations of the bilayer structure elucidate the importance of the electronic properties at the interface between the TiO_(2) and SnO_(2) layers.The apparent correlation in hysteresis phenomena,including current density-voltage(J-V)curves,appears as a function of the type of band alignment.Density functional theory calculations reveal the intimate relationship between oxygen vacancies,deep trap states,and charge transport efficiency at the interface between the TiO_(2) and SnO_(2) layers.The formation of cascade band alignment via control over the TiO_(2) underlayer enhances device performance and suppresses hysteresis.Optimal performance exhibits a power conversion efficiency(PCE)of 23.45%with an open-circuit voltage(V_(oc))of 1.184 V,showing better device stability under maximum power point tracking compared with a staggered bilayer under one-sun continuous illumination.
基金supported by the National Natural Science Foundation of China (Grant No.10974183)
文摘Oxygen vacancy formation and migration in La0.9Sr0.1Ga0.8Mg0.2O3-5 （LSGM） with various crystal symmetries （cubic, rhombohedral, orthorhombic, and monoclinic） are studied by employing first-principles calculations based on density functional theory （DFT）. It is shown that the cubic LSGM has the smallest band gap, oxygen vacancy formation energy, and migration barrier, while the other three structures give rise to much larger values for these quantities, implying the best oxygen ion conductivity of the cubic LSGM among the four crystal structures. In out calculations, one oxygen vacancy migration pathway is considered in the cubic and rhombohedral structures due to all the oxygen sites being equivalent in them, while two vacancy migration pathways with different migration barriers are found in the orthorhombic and monoclinic symmetries owing to the existence of nonequivalent O1 and 02 oxygen sites. The migration energies along the migration pathway linking the two 02 sites are obviously lower than those along the pathway linking the O1 and 02 sites. Considering the phase transitions at high temperatures, the results obtained in this paper can not only explain the experimentally observed different behaviours of the oxygen ionic conductivity of LSGM with different symmetries, but also predict the rational crystal structures of LSGM for solid oxide fuel cell applications.
文摘Oxygen vacancy （Ov） has significant influence on physical and chemical properties of TiO2 systems, especially on surface catalytic processes. In this work, we investigate the effects of Ov on the adsorption of formaldehyde （HCHO） on TiO2（110） surfaces through first- principles calculations. With the existence of Ov, we find the spatial distribution of surface excess charge can change the relative stability of various adsorption configurations. In this case, the bidentate adsorption at five-coordinated Ti （Tisc） can be less stable than the monodentate adsorption. And HCHO adsorbed in Ov becomes the most stable structure. These results are in good agreement with experimental observations, which reconcile the long-standing deviation between the theoretical prediction and experimental results. This work brings insights into how the excess charge affects the molecule adsorption on metal oxide surface.
基金This work was supported by the National Natural Sci- ence Foundation of China （No.11034006, No.21273208, and No.21473168）, the Anhui Provincial Natural Sci- ence Foundation （No.1408085QB26）, the hmdamental Research Funds for the Central Universities, the China Postdoctoral Science Foundation （No.2012M511409）, and the Supercomputing Center of Chinese Academy of Sciences, Shanghai and USTC Supercomputer Cen- ters.
文摘Doping with various impurities is an effective approach to improve the photoelectrochemical properties of TiO2. Here, we explore the effect of oxygen vacancy on geometric and elec- tronic properties of compensated （i.e. V-N and Cr-C） and non-compensated （i.e. V-C and Cr-N） codoped anatase TiO2 by performing extensive density functional theory calculations. Theoretical results show that oxygen vacancy prefers to the neighboring site of metal dopant （i.e. V or Cr atom）. After introduction of oxygen vacancy, the unoccupied impurity bands located within band gap of these codoped TiO2 will be filled with electrons, and the posi- tion of conduction band offset does not change obviously, which result in the reduction of photoinduced carrier recombination and the good performance for hydrogen production via water splitting. Moreover, we find that oxygen vacancy is easily introduced in V-N codoped TiO2 under O-poor condition. These theoretical insights are helpful for designing codoped TiO2 with high photoelectrochemical performance.
基金supported by the National Natural Science Foundation of China(21501016,51501024,51871037 and 21822601)the Fundamental Research Funds for the Central Universities(2018CDQYCL0027)~~
文摘Bi2MoO6,a typical Bi-based photocatalyst,has received increasing interests and been widely applied in various fields.However,the visible light photocatalytic activity of Bi2MoO6 is still restricted by some obstacles,such as limited photo-response and low charge separation efficiency.In this work,we developed a facile method to introduce artificial oxygen vacancy into Bi2MoO6 microspheres,which could effectively address these problems and realize highly efficient visible light photocatalysis.The experimental and theoretical methods were combined to explore the effects of oxygen vacancy on the electronic structure,photocatalytic activity and the reaction mechanism toward NO removal.The results showed that the addition of NaBH4 during catalyst preparation induced the formation of oxygen vacancy in Bi2MoO6,which plays a significant role in extending the visible light absorption of Bi2MoO6.The visible light photocatalytic activity of Bi2MoO6 with oxygen vacancy was obviously enhanced with a NO removal ratio of 43.5%,in contrast to that of 25.0%with the pristine Bi2MoO6.This can be attributed to the oxygen vacancy that creates a defect energy level in the band gap of Bi2MoO6,thus facilitating the charge separation and transfer processes.Hence,more reactive radicals were generated and participated in the photocatalytic NO oxidation reaction.The in situ FT-IR was used to dynamically monitor the photocatalytic NO oxidation process.The reaction intermediates were observed and the adsorption-reaction mechanism was proposed.It was found that the reaction mechanism was unchanged by introducing the oxygen vacancy in Bi2MoO6.This work could provide new insights into the understanding of the oxygen vacancy in photocatalysis and gas-phase photocatalytic reaction mechanism.
基金supported by the National Natural Science Foundation of China(Nos.21671172,21625604,21776251,21706229and Z86101001)Zhejiang Provincial Natural Science Foundation(No.LR19B010001)
文摘To search the new effective nitrogen reduction reaction(NRR)electrocatalyst is very important for the ammonia-based industry.Herein,we reported the design of a novel NRR electrocatalyst with Ru NPs loaded on oxygen-vacancy TiO2(Ru/TiO2-Vo).Structural characterizations revealed that oxygen vacancy was loaded in the matrix of Ru/TiO2-Vo.Electrocatalytic results indicated that Ru/TiO2-Vo showed good NRR performance(2.11μg h^-1 cm^-2).Contrast tests showed that NRR property of Ru/TiO2-Vo was much better than those of Ru/TiO-12(B)(0.53μg hcm^-2)and Ru/P25(0.42μg h^-1 cm^-2).Furthermore,density functional theory calculation results indicated catalytic mechanism of NRR and rate-determining step(*N2+1/2 H2→*N+*NH)was the potential-determining step with the overpotential requirement of 0.21 V.A combination of electronic structure analysis and catalytic measurement shed light on the synergistic effect of Ru and oxygen vacancy on the NRR performance.
文摘Surface defect modulation has emerged as a potential strategy for promoting the photocatalytic activity of photocatalysts for various applications, while the impact of the oxygen vacancy on bacterial inactivation is still debated. In this study, oxygen vacancies were introduced to tungsten trioxide nanosheets(WO3–x) via a microwave-assisted route. The as-prepared WO3–x nanosheets exhibited excellent visible-light-driven photocatalytic activity toward E. coli K-12 inactivation, and 6 log orders of the bacterial cells could be completely inactivated within 150 min. The obtained bacterial inactivation rate constant was 15.2 times higher than that of pristine WO3 without oxygen vacancies, suggesting that the surface oxygen vacancy could significantly promote the bacterial inactivation efficiency. The mechanism study indicated that the inactivation of bacterial cells occurs via a direct h+ oxidation pathway. In addition, the role of the oxygen vacancy was studied in detail;the oxygen vacancy was found to not only promote interfacial charge separation but also tune the band structure of WO3, thereby leading to increased h+ oxidation power. Finally, a possible oxygen vacancy-dominated photocatalytic bacterial inactivation mechanism is proposed. This work is expected to offer new insights into the microwave-assisted synthesis of defective photocatalysts and the use of the oxygen vacancy for promoting photocatalytic antibacterial activities.
文摘Photocatalytic degradation of gaseous pollutants on Bi-based semiconductors under solar lightirradiation has attracted significant attention.However,their application in gaseous straight-chainalkane purification is still rare.Here,a series of Bi/BiOBr composites were solvothermally synthe-sized and applied in solar-light-driven photocatalytic degradation of gaseous n-hexane.The charac-terization results revealed that both increasing number of functional groups of alcohol solvent(from methanol and ethylene glycol to glycerol)and solvothermal temperature(from 160 and 180to 200℃)facilitated the in-situ formation of metallic Bi nanospheres on BiOBr nanoplates withexposed(110)facets.Meanwhile,chemical bonding between Bi and BiOBr was observed on theseexposed facets that resulted in the formation of surface oxygen vacancy.Furthermore,the synergis-tic effect of optimum surface oxygen vacancy on exposed(110)facets led to a high visible light re-sponse,narrow band gap,great photocurrent,low recombination rate of the charge carriers,andstrong·O2-and h*formation,all of which resulted in the highest removal efficiency of 97.4%within120 min of 15 ppmv of n-hexane on Bi/BiOBr.Our findings efficiently broaden the application ofBi-based photocatalysis technology in the purification of gaseous straight-chain pollutants emittedby the petrochemical industry.
基金financially supported by the National Natural Science Foundation of China(Grants 52072165,52070092,51662031)。
文摘Oxygen vacancy plays vital roles in regulating the electronic and charge distribution of the oxygen deficient materials.Herein,abundant oxygen vacancies are created during assembling the two-dimensional(2D)ultra-thin Bi_(2)MoO_(6) nanoflakes into three dimensional(3D)Bi_(2)MoO_(6) nanospheres,resulting in significantly improved performance for photocatalytical conversion of CO_(2) into liquid hydrocarbons.The increased performance is contributed by two primary sites,namely the abundant oxygen vacancy and the exposed molybdenum(Mo)atom induced by oxygen-migration,as revealed by the theoretical calculation.The oxygen vacancy(Ov)and uncovered Mo atom serving as dual binding sites for trapping CO_(2) molecules render the synchronous fixation-reduction process,resulting in the decline of activation energy for CO_(2) reduction from 2.15 eV on bulk Bi_(2)MoO_(6) to 1.42 eV on Ov-rich Bi_(2)MoO_(6).Such a striking decrease in the activation energy induces the efficient selective generation of liquid hydrocarbons,especially the methanol(C_(2)H_(5) OH)and ethanol(CH_(3) OH).The yields of CH_(3) OH and C_(2)H_(5) OH over the optimal Ov-Bi_(2)MoO_(6) is high up to 106.5 and 10.3μmol g^(-1) respectively,greatly outperforming that on the Bulk-Bi_(2)MoO_(6).
基金This work was financially supported by the Australian Research Council(ARC)through Future Fellowship grants(FT180100387 and FT160100281)Discovery Projects(DP200103568,DP210100472,and DP200102546)+1 种基金WL thanks the support of the Science and Technology Commission of Shanghai Municipality(19520713200)Open access funding provided by Shanghai Jiao Tong University
文摘Oxygen vacancies(Vo)in electrocatalysts are closely correlated with the hydrogen evo-lution reaction(HER)activity.The role of vacancy defects and the effect of their concentration,how-ever,yet remains unclear.Herein,Bi2O3,an unfavorable electrocata-lyst for the HER due to a less than ideal hydrogen adsorption Gibbs free energy(ΔGH*),is utilized as a perfect model to explore the func-tion of Vo on HER performance.Through a facile plasma irradia-tion strategy,Bi2O3 nanosheets with different Vo concentrations are fabricated to evaluate the influence of defects on the HER process.Unexpectedly,while the generated oxygen vacancies contribute to the enhanced HER performance,higher Vo concentrations beyond a saturation value result in a significant drop in HER activity.By tunning the Vo concentration in the Bi_(2)O_(3)nanosheets via adjusting the treatment time,the Bi2O3 catalyst with an optimized oxygen vacancy concentration and detectable charge carrier concentration of 1.52×10^(24)cm^(−3)demonstrates enhanced HER performance with an overpotential of 174.2 mV to reach 10 mA cm^(−2),a Tafel slope of 80 mV dec−1,and an exchange current density of 316 mA cm−2 in an alkaline solution,which approaches the top-tier activity among Bi-based HER electrocatalysts.Density-functional theory calculations confirm the preferred adsorption of H*onto Bi2O3 as a function of oxygen chemical potential(ΔμO)and oxygen partial potential(PO2)and reveal that high Vo concentrations result in excessive stability of adsorbed hydrogen and hence the inferior HER activity.This study reveals the oxygen vacancy concentration-HER catalytic activity relationship and provides insights into activating catalytically inert materials into highly efficient electrocatalysts.
基金supported by the National Natural Science Foundation of China (Nos. 21536008 and 21621004).
文摘Indium oxide supported nickel catalyst has been experimentally confirmed to be highly active for CO_(2) hydrogenation towards methanol.In this work,the reaction mechanism for CO_(2) hydrogenation to methanol has been investigated on a model Ni/In_(2)O_(3) catalyst,i.e.,Ni_(4)/In_(2)O_(3),via the density functional theory(DFT)study.Three possible reaction pathways,i.e.,the formate pathway,CO hydrogenation and the reverse water-gas-shift(RWGS)pathways,have been examined on this model catalyst.It has been demonstrated that the RWGS pathway is the most theoretically-favored for CO_(2) hydrogenation to methanol.The complete RWGS pathway follows CO_(2)+6 H→COOH+5 H→CO+H_(2)O+4 H→HCO+H_(2)O+3 H→H_(2)CO+H_(2)O+2 H→H_(3)CO+H_(2)O+H→H_(3)COH+H_(2) O.Furthermore,it has been also proved that the interfacial oxygen vacancy can serve as the active site for boosting the CO_(2) adsorption and charge transfer between the nickel species and indium oxide,which synergistically promotes the consecutive CO_(2) hydrogenation towards methanol.
基金the financial supports from the MOST (2019YFE0191500)the Natural Science Foundation of Jiangsu Province of China (BK20211172)the Fundamental Research Funds for the Central Universities
文摘Although sodium ion capacitors(SICs)are considered as one of the most promising electrochemical energy storage devices(organic electrolyte batteries,aqueous batteries and supercapacitor,etc.)due to the combined merits of battery and capacitor,the slow reaction kinetics and low specific capacity of anode materials are the main challenges.Point defects including vacancies and heteroatoms doping have been widely used to improve the kinetics behavior and capacity of anode materials.However,the interaction between vacancies and heteroatoms doping have been seldomly investigated.In this study,a hybrid point defects(HPD)engineering has been proposed to synthesize TiO_(2) with both oxygen vacancies(OVs)and P-dopants(TiO_(2)/C-HPD).In comparison with sole OVs or P-doping treatments,the synergistic effects of HPD on its electrical conductivity and sodium storage performance have been clarified through the density func-tional theory calculation and sodium storage characterization.As expected,the kinetics and electronic conductivity of TiO_(2)/C-HPD3 are significantly improved,resulting in excellent rate performance and outstanding cycle stability.Moreover,the SICs assembled from TiO_(2)/C-HPD3 anode and nitrogen-doped porous carbon cathode show outstanding power/energy density,ultra-long life with good capacity retention.This work provides a novel point defect engineering perspective for the development of high-performance SICs electrode materials.
基金financially supported by the National Natural Science Foundation of China(U1867215,11722543,11875211,U1932134)Suzhou Key Industrial Technology Innovation project(SYG201828)+1 种基金Hubei Provincial Natural Science Foundation(2019CFA036)the Fundamental Research Funds for the Central Universities(2042020kf0211)
文摘Despite the tremendous efforts devoted to enhancing the activity of oxygen evolution reaction(OER)catalysts,there is still a huge challenge to deeply understand the electronic structure characteristics of transition metal oxide to guide the design of more active catalysts.Herein,Fe_(3)O_(4)with oxygen vacancies(Fe_(3)O_(4)-Vac)was synthesized via Ar ion irradiation method and its OER activity was greatly improved by properly modulating the electron density around Fe atoms.The electron density of Fe_(3)O_(4)-Vac around Fe atoms increased compared to that of Fe_(3)O_(4)according to the characterization of synchrotron-based X-ray absorption near-edge structure(XANES),extended X-ray absorption fine structure(EXAFS)spectra,and density functional theory(DFT)calculation.Moreover,the DFT results indicate the enhancement of the desorption of HOO^(*)groups which significantly reduced the OER reaction barrier.Fe_(3)O_(4)-Vac catalyst shows an overpotential of 353 m V,lower than that of Fe OOH(853 m V)and Fe_(3)O_(4)(415 m V)at 10 m A cm^(-2),and a low Tafel slope of 50 m V dec^(-1)in 1 M KOH,which was even better than commercial RuO_(2)at high potential.This modulation approach provides us with valuable insights for exploring efficient and robust water-splitting electrocatalysts.
文摘The SnO2-x. with different oxygen vacancy concentrations was modified by addling Sm. The modified SnO2-x was investigated by means of X-ray diffraction, X-ray photoelectron spectroscope, and scanning electron microscopy. Its gas-sensing properties to C2H6, C6H14, C2H5OH, CO, and H2 were studied too. The experiment results show that the gas-sensing properties of Sm/SnO2-x depend upon the amount of oxygen vacancies, therefore it is possible to improve gas-sensing properties of doped SnO2 by controlling its concentration of oxygen vacancy.
