Ni-rich layered oxide cathodes have shown promise for high-energy lithium-ion batteries(LIBs)but are usually limited to mild environments because of their rapid performance degradation under extreme temperature condit...Ni-rich layered oxide cathodes have shown promise for high-energy lithium-ion batteries(LIBs)but are usually limited to mild environments because of their rapid performance degradation under extreme temperature conditions(below0°C and above 50 °C).Here,we report the design of F/Mo co-doped LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2)(FMNCM)cathode for high-performance LIBs from-20 to 60°C.F^(-) doping with high electronegativity into the cathode surface is found to enhance the stability of surface lattice structure and protect the interface from side reactions with the electrolyte by generating a LiF-rich surface layer.Concurrently,the Mo^(6+) doping suppresses phase transition,which blocks Li^(+)/Ni^(2+) mixing,and stabilizes lithium-ion diffusion pathway.Remarkably,the FMNCM cathode demonstrates excellent cycling stability at a high cutoff voltage of 4.4 V,even at 60°C,maintaining 90.6%capacity retention at 3 C after 150 cycles.Additionally,at temperatures as low as-20°C,it retains 77.1%of its room temperature capacity,achieving an impressive 97.5%capacity retention after 500 cycles.Such stable operation under wide temperatures has been further validated in practical Ah-level pouch-cells.This study sheds light on both fundamental mechanisms and practical implications for the design of advanced cathode materials for wide-temperature LIBs,presenting a promising path towards high-energy and long-cycling LIBs with temperatureadaptability.展开更多
Layered LiCoO_(2)(LCO)acts as a dominant cathode material for lithium-ion batteries(LIBs)in 3C products because of its high compacted density and volumetric energy density.Although improving the high cutoff voltage is...Layered LiCoO_(2)(LCO)acts as a dominant cathode material for lithium-ion batteries(LIBs)in 3C products because of its high compacted density and volumetric energy density.Although improving the high cutoff voltage is an effective strategy to increase its capacity,such behavior would trigger rapid capacity decay due to the surface or/and structure degradation.Herein,we propose a bi-functional surface strategy involving constructing a robust spinel-like phase coating layer with great integrity and compatibility to LiCoO_(2) and modulating crystal lattice by anion and cation gradient co-doping at the subsurface.As a result,the modified LiCoO_(2)(AFM-LCO)shows a capacity retention of 80.9%after 500 cycles between 3.0and 4.6 V.The Al,F,Mg enriched spinel-like phase coating layer serves as a robust physical barrier to effectively inhibit the undesired side reactions between the electrolyte and the cathode.Meanwhile,the Al,F,Mg gradient co-doping significantly enhances the surficial structure stability,suppresses Co dissolution and oxygen release,providing a stable path for Li-ions mobility all through the long-term cycles.Thus,the surface bi-functional strategy is an effective method to synergistically improve the electrochemical performances of LCO at a high cut-off voltage of 4.6 V.展开更多
Biomass-derived carbon has demonstrated great potentials as advanced electrode for capacitive deionization(CDI),owing to good electroconductivity,easy availability,intrinsic pores/channels.However,conventional simple ...Biomass-derived carbon has demonstrated great potentials as advanced electrode for capacitive deionization(CDI),owing to good electroconductivity,easy availability,intrinsic pores/channels.However,conventional simple pyrolysis of biomass always generates inadequate porosity with limited surface area.Moreover,biomass-derived carbon also suffers from poor wettability and single physical adsorption of ions,resulting in limited desalination performance.Herein,pore structure optimization and element co-doping are integrated on banana peels(BP)-derived carbon to construct hierarchically porous and B,N co-doped carbon with large ions-accessible surface area.A unique expansionactivation(EA)strategy is proposed to modulate the porosity and specific surface area of carbon.Furthermore,B,N co-doping could increase the ions-accessible sites with improved hydrophilicity,and promote ions adsorption.Benefitting from the synergistic effect of hierarchical porosity and B,N co-doping,the resultant electrode manifest enhanced CDI performance for NaCl with large desalination capacity(29.5 mg g^(-1)),high salt adsorption rate(6.2 mg g^(-1)min^(-1)),and versatile adsorption ability for other salts.Density functional theory reveals the enhanced deionization mechanism by pore and B,N co-doping.This work proposes a facile EA strategy for pore structure modulation of biomass-derived carbon,and demonstrates great potentials of integrating pore and heteroatoms-doping on constructing high-performance CDI electrode.展开更多
Sodium-ion batteries(SIBs) and hybrid capacitors(SIHCs) have garnered significant attention in energy storage due to their inherent advantages,including high energy density,cost-effectiveness,and enhanced safety.Howev...Sodium-ion batteries(SIBs) and hybrid capacitors(SIHCs) have garnered significant attention in energy storage due to their inherent advantages,including high energy density,cost-effectiveness,and enhanced safety.However,developing high-performance anode materials to improve sodium storage performa nce still remains a major challenge.Here,a facile one-pot method has been developed to fabricate a hybrid of MoSeTe nanosheets implanted within the N,F co-doped honeycomb carbon skeleton(MoSeTe/N,F@C).Experimental results demonstrate that the incorporation of large-sized Te atoms into MoSeTe nanosheets enlarges the layer spacing and creates abundant anion vacancies,which effectively facilitate the insertion/extraction of Na^(+) and provide numerous ion adsorption sites for rapid surface capacitive behavior.Additionally,the heteroatoms N,F co-doped honeycomb carbon skeleton with a highly conductive network can restrain the volume expansion and boost reaction kinetics within the electrode.As anticipated,the MoSeTe/N,F@C anode exhibits high reversible capacities along with exceptional cycle stability.When coupled with Na_(3)V_(2)(PO_(4))_(3)@C(NVPF@C) to form SIB full cells,the anode delivers a reversible specific capacity of 126 mA h g^(-1) after 100 cycles at 0.1 A g^(-1).Furthermore,when combined with AC to form SIHC full cells,the anode demonstrates excellent cycling stability with a reversible specific capacity of50 mA h g^(-1) keeping over 3700 cycles at 1.0 A g^(-1).In situ XRD,ex situ TEM characterization,and theoretical calculations(DFT) further confirm the reversibility of sodium storage in MoSeTe/N,F@C anode materials during electrochemical reactions,highlighting their potential for widespread practical application.This work provides new insights into the promising utilization of advanced transition metal dichalcogenides as anode materials for Na^(+)-based energy storage devices.展开更多
S and Co co-doped carbon catalysts were prepared via pyrolysis of MOF-71 and thiourea mixtures at 800℃at a mass ratio of MOF-71 to thiourea of 1:0.1 to effectively activate peroxymonosulfate(PMS)for methylene blue(MB...S and Co co-doped carbon catalysts were prepared via pyrolysis of MOF-71 and thiourea mixtures at 800℃at a mass ratio of MOF-71 to thiourea of 1:0.1 to effectively activate peroxymonosulfate(PMS)for methylene blue(MB)degradation.The effects of two different mixing routes were identified on the MB degradation performance.Particularly,the catalyst obtained by the alcohol solvent evaporation(MOF-AEP)mixing route could degrade 95.60%MB(50 mg/L)within 4 min(degradation rate:K=0.78 min^(-1)),which was faster than that derived from the direct grinding method(MOF-DGP,80.97%,K=0.39 min^(-1)).X-ray photoelectron spectroscopy revealed that the Co-S content of MOF-AEP(43.39at%)was less than that of MOF-DGP(54.73at%),and the proportion of C-S-C in MOF-AEP(13.56at%)was higher than that of MOF-DGP(10.67at%).Density functional theory calculations revealed that the adsorption energy of Co for PMS was -2.94 eV when sulfur was doped as C-S-C on the carbon skeleton,which was higher than that when sulfur was doped next to cobalt in the form of Co-S bond(-2.86 eV).Thus,the C-S-C sites might provide more contributions to activate PMS compared with Co-S.Furthermore,the degradation parameters,including pH and MOF-AEP dosage,were investigated.Finally,radical quenching experiments and electron paramagnetic resonance(EPR)measurements revealed that ^(1)O_(2)might be the primary catalytic species,whereas·O~(2-)might be the secondary one in degrading MB.展开更多
Carbonaceous materials have drawn much attention in potassium-ion batteries (PIBs) due to their low price and superior physicochemical properties. However, the application of carbonaceous materials in PIB anodes is hi...Carbonaceous materials have drawn much attention in potassium-ion batteries (PIBs) due to their low price and superior physicochemical properties. However, the application of carbonaceous materials in PIB anodes is hindered by sluggish kinetics and large volume expansion. Herein, N/S co-doped carbon nanocapsule (NSCN) is constructed for superior K+ storage. The NSCN possesses 3D nanocapsule framework with abundant meso/macropores, which guarantees structural robustness and accelerates ions/electrons transportation. The high-level N/S co-doping in carbon matrix not only generates ample defects and active sites for K+ adsorption, but also expands interlayer distance for facile K+ intercalation/deintercalation. As a result, the NSCN electrode delivers a high reversible capacity (408 mAh g^(−1) at 0.05 A g^(−1)), outstanding rate capability (149 mAh g^(−1) at 5 A g^(−1)) and favorable cycle stability (150m Ah g^(−1) at 2 A g^(−1) after 2000 cycles). Ex situ TEM, Raman and XPS measurements demonstrate the excellent stability and reversibility of NSCN electrode during potassiation/depotassiation process. This work provides inspiration for the optimization of energy storage materials by structure and doping engineering.展开更多
The geometric structure, band structure and density of states of pure, Ag-doped, N-doped, and N-Ag codoped wurtzite ZnO have been investigated by the first-principles ultra-soft pseudopotential method based on the den...The geometric structure, band structure and density of states of pure, Ag-doped, N-doped, and N-Ag codoped wurtzite ZnO have been investigated by the first-principles ultra-soft pseudopotential method based on the density functional theory. The calculated results show that the carrier concentration is increased in the ZnO crystal codoped by N and Ag, and the codoped structure is stable and is more in favour of the formation of p-type ZnO.展开更多
Although CoO is a promising electrode material for supercapacitors due to its high theoretical capacitance,the practical applications still suffering from inferior electrochemical activity owing to its low electrical ...Although CoO is a promising electrode material for supercapacitors due to its high theoretical capacitance,the practical applications still suffering from inferior electrochemical activity owing to its low electrical conductivity,poor structural stability and inefficient nanostructure.Herein,we report a novel Cu0/Cu+co-doped CoO composite with adjustable metallic Cu0 and ion Cu+via a facile strategy.Through interior(Cu+)and exterior(Cu0)decoration of CoO,the electrochemical performance of CoO electrode has been significantly improved due to both the beneficial flower-like nanostructure and the synergetic effect of Cu0/Cu+co-doping,which results in a significantly enhanced specific capacitance(695 F g^(-1) at 1 A g^(-1))and high cyclic stability(93.4%retention over 10,000 cycles)than pristine CoO.Furthermore,this co-doping strategy is also applicable to other transition metal oxide(NiO)with enhanced electrochemical performance.In addition,an asymmetric hybrid supercapacitor was assembled using the Cu0/Cu+co-doped CoO electrode and active carbon,which delivers a remarkable maximal energy density(35 Wh kg^(-1)),exceptional power density(16 kW kg^(-1))and ultralong cycle life(91.5%retention over 10,000 cycles).Theoretical calculations further verify that the co-doping of Cu^(0)/Cu^(+)can tune the electronic structure of CoO and improve the conductivity and electron transport.This study demonstrates a facile and favorable strategy to enhance the electrochemical performance of transition metal oxide electrode materials.展开更多
Green light-emitting Ba2SiO4：Eu^2＋ phosphors co-doped with La or Y were synthesized by conventional solid-state reaction technique in reductive atmosphere（a mixture of 5% H2 and 95% N2）.The results showed that the...Green light-emitting Ba2SiO4：Eu^2＋ phosphors co-doped with La or Y were synthesized by conventional solid-state reaction technique in reductive atmosphere（a mixture of 5% H2 and 95% N2）.The results showed that the co-doping of La and Y could greatly enhance the fluorescence intensity of Ba2SiO4：Eu2＋ phosphors.The optimum doping concentration expressed by the x value in（Ba0.985-1.5xREx）2SiO4：0.03Eu^2＋（RE=La or Y） was determined to be of 0.05.The excitation and emission peaks of all as-synthesized phosphors were wide bands.The excitation bands ranged from 250 to 400 nm, which matched well with the wavelength of near ultraviolet white light-emitting diodes（LED） chip and could be used as a potential candidate for the fabrication of white LED.The emission bands from 450 to 550 nm were typical 5d-4f transition emission of Eu^2＋ and displayed un-symmetry profiles because of the two substitution sites of Ba^2＋ with Eu^2＋.展开更多
Electrochemical reduction of CO_(2)(CERR)to value-added chemicals is an attractive strategy for greenhouse gas mitigation,and carbon recycles utilization.Conventional metal catalysts suffered from low durability and s...Electrochemical reduction of CO_(2)(CERR)to value-added chemicals is an attractive strategy for greenhouse gas mitigation,and carbon recycles utilization.Conventional metal catalysts suffered from low durability and sluggish kinetics impede the practical application.On the other hand,doped carbon materials recently demonstrate superior catalytic performance in CERR,which shows the potential to diminish the problems of metal catalysts to some extent.Herein,we present the design and fabrication of nitrogen(N),phosphorus(P)co-doped metal-free carbon materials as an efficient and stable electrocatalyst for reduction of CO_(2) to CO,which exhibits an excellent performance with a high faradaic efficiency of 92%(-0.55 V vs.RHE)and up to 24 h stability.A series of characterizations including TEM and XPS verified that nitrogen and phosphorous are successfully incorporated into the carbon matrix.Moreover,the comparisons between co-doping and single doping catalysts reveal that co-doping can significantly increase CERR performance.The improved catalytic activity is attributed to the synergetic effects between nitrogen and phosphorous dopants,which effectively modulate properties of the active site.The density functional theory(DFT)calculations were also performed to understand the synergy effects of dopants.It is revealed that the phosphorous doping can significantly lower the Gibbs free energy of COOH^(*)formation.Moreover,the introduction of the second dopants phosphorous can reduce the reaction barrier along the reaction path and cause polarization of density of states at the Fermi level.These changes can greatly enhance the activity of the catalysts.From a combined experimental and computational exploration,current work provides valuable insights into the reaction mechanism of CERR on N,P co-doped carbon catalysts,and the influence from synergy effects between dopants,which paves the way for the rational design of novel metal-free catalysts for CO2 electro-reduction.展开更多
Using the first-principles calculations, we investigate the electronic band structure and the quantum transport properties of metallic carbon nanotubes （MCNTs） with B/N pair co-doping. The results about formation en...Using the first-principles calculations, we investigate the electronic band structure and the quantum transport properties of metallic carbon nanotubes （MCNTs） with B/N pair co-doping. The results about formation energy show that the B/N pair co-doping configuration is a most stable structure. We find that the electronic structure and the transport properties are very sensitive to the doping concentration of the B/N pairs in MCNTs, where the energy gaps increase with doping concentration increasing both along the tube axis and around the tube, because the mirror symmetry of MCNT is broken by doping B/N pairs. In addition, we discuss conductance dips of the transmission spectrum of doped MCNTs. These unconventional doping effects could be used to design novel nanoelectronic devices.展开更多
基金the financial support from the National Natural Science Foundation of China(51972156,52072378,52102054 and 51927803)the National Key R&D Program of China(2022YFB3803400,2021YFB3800301)+2 种基金the Shenyang Science and Technology Program(22-322-3-19)the Youth Fund of the Education Department of Liaoning Province(LJKQZ20222324)the Outstanding Youth Fund of University of Science and Technology Liaoning(2023YQ11).
文摘Ni-rich layered oxide cathodes have shown promise for high-energy lithium-ion batteries(LIBs)but are usually limited to mild environments because of their rapid performance degradation under extreme temperature conditions(below0°C and above 50 °C).Here,we report the design of F/Mo co-doped LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2)(FMNCM)cathode for high-performance LIBs from-20 to 60°C.F^(-) doping with high electronegativity into the cathode surface is found to enhance the stability of surface lattice structure and protect the interface from side reactions with the electrolyte by generating a LiF-rich surface layer.Concurrently,the Mo^(6+) doping suppresses phase transition,which blocks Li^(+)/Ni^(2+) mixing,and stabilizes lithium-ion diffusion pathway.Remarkably,the FMNCM cathode demonstrates excellent cycling stability at a high cutoff voltage of 4.4 V,even at 60°C,maintaining 90.6%capacity retention at 3 C after 150 cycles.Additionally,at temperatures as low as-20°C,it retains 77.1%of its room temperature capacity,achieving an impressive 97.5%capacity retention after 500 cycles.Such stable operation under wide temperatures has been further validated in practical Ah-level pouch-cells.This study sheds light on both fundamental mechanisms and practical implications for the design of advanced cathode materials for wide-temperature LIBs,presenting a promising path towards high-energy and long-cycling LIBs with temperatureadaptability.
基金supported by the National Natural Science Foundation of China(22075170,52072233)the Beijing National Laboratory for Condensed Matter Physics。
文摘Layered LiCoO_(2)(LCO)acts as a dominant cathode material for lithium-ion batteries(LIBs)in 3C products because of its high compacted density and volumetric energy density.Although improving the high cutoff voltage is an effective strategy to increase its capacity,such behavior would trigger rapid capacity decay due to the surface or/and structure degradation.Herein,we propose a bi-functional surface strategy involving constructing a robust spinel-like phase coating layer with great integrity and compatibility to LiCoO_(2) and modulating crystal lattice by anion and cation gradient co-doping at the subsurface.As a result,the modified LiCoO_(2)(AFM-LCO)shows a capacity retention of 80.9%after 500 cycles between 3.0and 4.6 V.The Al,F,Mg enriched spinel-like phase coating layer serves as a robust physical barrier to effectively inhibit the undesired side reactions between the electrolyte and the cathode.Meanwhile,the Al,F,Mg gradient co-doping significantly enhances the surficial structure stability,suppresses Co dissolution and oxygen release,providing a stable path for Li-ions mobility all through the long-term cycles.Thus,the surface bi-functional strategy is an effective method to synergistically improve the electrochemical performances of LCO at a high cut-off voltage of 4.6 V.
基金We gratefully acknowledge financial supports from the National Natural Science Foundation of China(No.52202371,51905125,52102364)the Natural Science Foundation of Shandong Province(No.ZR2020QE066)+2 种基金Opening Project of State Key Laboratory of Advanced Technology for Float Glass(No.2020KF08)SDUT&Zibo City Integration Development Project(No.2021SNPT0045)the fellowship of China Postdoctoral Science Foundation(No.2020M672081).
文摘Biomass-derived carbon has demonstrated great potentials as advanced electrode for capacitive deionization(CDI),owing to good electroconductivity,easy availability,intrinsic pores/channels.However,conventional simple pyrolysis of biomass always generates inadequate porosity with limited surface area.Moreover,biomass-derived carbon also suffers from poor wettability and single physical adsorption of ions,resulting in limited desalination performance.Herein,pore structure optimization and element co-doping are integrated on banana peels(BP)-derived carbon to construct hierarchically porous and B,N co-doped carbon with large ions-accessible surface area.A unique expansionactivation(EA)strategy is proposed to modulate the porosity and specific surface area of carbon.Furthermore,B,N co-doping could increase the ions-accessible sites with improved hydrophilicity,and promote ions adsorption.Benefitting from the synergistic effect of hierarchical porosity and B,N co-doping,the resultant electrode manifest enhanced CDI performance for NaCl with large desalination capacity(29.5 mg g^(-1)),high salt adsorption rate(6.2 mg g^(-1)min^(-1)),and versatile adsorption ability for other salts.Density functional theory reveals the enhanced deionization mechanism by pore and B,N co-doping.This work proposes a facile EA strategy for pore structure modulation of biomass-derived carbon,and demonstrates great potentials of integrating pore and heteroatoms-doping on constructing high-performance CDI electrode.
基金supported by the National Natural Science Foundation of China(No.52002320,and 51972267)the China Postdoctoral Science Foundation(No.2022M712574)+3 种基金the Science Foundation of Shaanxi Province(2022GD-TSLD-18,No.2023-JCZD-03)Natural Science Foundation of Shaanxi Province(No.2022GY-372,2021GY-153)Industrial Projects Foundation of Ankang Science and Technology Bureau(No.AK2020-GY02-2)the Platform Construction Projects and Technology Service Teams of Ankang University(No.2021AYPT12 and 2022TD07)。
文摘Sodium-ion batteries(SIBs) and hybrid capacitors(SIHCs) have garnered significant attention in energy storage due to their inherent advantages,including high energy density,cost-effectiveness,and enhanced safety.However,developing high-performance anode materials to improve sodium storage performa nce still remains a major challenge.Here,a facile one-pot method has been developed to fabricate a hybrid of MoSeTe nanosheets implanted within the N,F co-doped honeycomb carbon skeleton(MoSeTe/N,F@C).Experimental results demonstrate that the incorporation of large-sized Te atoms into MoSeTe nanosheets enlarges the layer spacing and creates abundant anion vacancies,which effectively facilitate the insertion/extraction of Na^(+) and provide numerous ion adsorption sites for rapid surface capacitive behavior.Additionally,the heteroatoms N,F co-doped honeycomb carbon skeleton with a highly conductive network can restrain the volume expansion and boost reaction kinetics within the electrode.As anticipated,the MoSeTe/N,F@C anode exhibits high reversible capacities along with exceptional cycle stability.When coupled with Na_(3)V_(2)(PO_(4))_(3)@C(NVPF@C) to form SIB full cells,the anode delivers a reversible specific capacity of 126 mA h g^(-1) after 100 cycles at 0.1 A g^(-1).Furthermore,when combined with AC to form SIHC full cells,the anode demonstrates excellent cycling stability with a reversible specific capacity of50 mA h g^(-1) keeping over 3700 cycles at 1.0 A g^(-1).In situ XRD,ex situ TEM characterization,and theoretical calculations(DFT) further confirm the reversibility of sodium storage in MoSeTe/N,F@C anode materials during electrochemical reactions,highlighting their potential for widespread practical application.This work provides new insights into the promising utilization of advanced transition metal dichalcogenides as anode materials for Na^(+)-based energy storage devices.
基金financially supported by the National Natural Science Foundation of China(Nos.51602018 and 51902018)the Natural Science Foundation of Beijing Municipality(No.2154052)+3 种基金the China Postdoctoral Science Foundation(No.2014M560044)the Fundamental Research Funds for the Central Universities(No.FRF-MP-20-22)USTB Research Center for International People-to-people Exchange in Science,Technology and Civilization(No.2022KFYB007)Education and Teaching Reform Foundation at University of Science and Technology Beijing(Nos.2023JGC027,KC2022QYW06,and KC2022TS09)。
文摘S and Co co-doped carbon catalysts were prepared via pyrolysis of MOF-71 and thiourea mixtures at 800℃at a mass ratio of MOF-71 to thiourea of 1:0.1 to effectively activate peroxymonosulfate(PMS)for methylene blue(MB)degradation.The effects of two different mixing routes were identified on the MB degradation performance.Particularly,the catalyst obtained by the alcohol solvent evaporation(MOF-AEP)mixing route could degrade 95.60%MB(50 mg/L)within 4 min(degradation rate:K=0.78 min^(-1)),which was faster than that derived from the direct grinding method(MOF-DGP,80.97%,K=0.39 min^(-1)).X-ray photoelectron spectroscopy revealed that the Co-S content of MOF-AEP(43.39at%)was less than that of MOF-DGP(54.73at%),and the proportion of C-S-C in MOF-AEP(13.56at%)was higher than that of MOF-DGP(10.67at%).Density functional theory calculations revealed that the adsorption energy of Co for PMS was -2.94 eV when sulfur was doped as C-S-C on the carbon skeleton,which was higher than that when sulfur was doped next to cobalt in the form of Co-S bond(-2.86 eV).Thus,the C-S-C sites might provide more contributions to activate PMS compared with Co-S.Furthermore,the degradation parameters,including pH and MOF-AEP dosage,were investigated.Finally,radical quenching experiments and electron paramagnetic resonance(EPR)measurements revealed that ^(1)O_(2)might be the primary catalytic species,whereas·O~(2-)might be the secondary one in degrading MB.
基金the financial supports from the National Natural Science Foundation of China(Grant Nos.51872005,U1508201,52072002)。
文摘Carbonaceous materials have drawn much attention in potassium-ion batteries (PIBs) due to their low price and superior physicochemical properties. However, the application of carbonaceous materials in PIB anodes is hindered by sluggish kinetics and large volume expansion. Herein, N/S co-doped carbon nanocapsule (NSCN) is constructed for superior K+ storage. The NSCN possesses 3D nanocapsule framework with abundant meso/macropores, which guarantees structural robustness and accelerates ions/electrons transportation. The high-level N/S co-doping in carbon matrix not only generates ample defects and active sites for K+ adsorption, but also expands interlayer distance for facile K+ intercalation/deintercalation. As a result, the NSCN electrode delivers a high reversible capacity (408 mAh g^(−1) at 0.05 A g^(−1)), outstanding rate capability (149 mAh g^(−1) at 5 A g^(−1)) and favorable cycle stability (150m Ah g^(−1) at 2 A g^(−1) after 2000 cycles). Ex situ TEM, Raman and XPS measurements demonstrate the excellent stability and reversibility of NSCN electrode during potassiation/depotassiation process. This work provides inspiration for the optimization of energy storage materials by structure and doping engineering.
文摘The geometric structure, band structure and density of states of pure, Ag-doped, N-doped, and N-Ag codoped wurtzite ZnO have been investigated by the first-principles ultra-soft pseudopotential method based on the density functional theory. The calculated results show that the carrier concentration is increased in the ZnO crystal codoped by N and Ag, and the codoped structure is stable and is more in favour of the formation of p-type ZnO.
基金financially supported by the National Science Foundation of China(Grant No.11804106)。
文摘Although CoO is a promising electrode material for supercapacitors due to its high theoretical capacitance,the practical applications still suffering from inferior electrochemical activity owing to its low electrical conductivity,poor structural stability and inefficient nanostructure.Herein,we report a novel Cu0/Cu+co-doped CoO composite with adjustable metallic Cu0 and ion Cu+via a facile strategy.Through interior(Cu+)and exterior(Cu0)decoration of CoO,the electrochemical performance of CoO electrode has been significantly improved due to both the beneficial flower-like nanostructure and the synergetic effect of Cu0/Cu+co-doping,which results in a significantly enhanced specific capacitance(695 F g^(-1) at 1 A g^(-1))and high cyclic stability(93.4%retention over 10,000 cycles)than pristine CoO.Furthermore,this co-doping strategy is also applicable to other transition metal oxide(NiO)with enhanced electrochemical performance.In addition,an asymmetric hybrid supercapacitor was assembled using the Cu0/Cu+co-doped CoO electrode and active carbon,which delivers a remarkable maximal energy density(35 Wh kg^(-1)),exceptional power density(16 kW kg^(-1))and ultralong cycle life(91.5%retention over 10,000 cycles).Theoretical calculations further verify that the co-doping of Cu^(0)/Cu^(+)can tune the electronic structure of CoO and improve the conductivity and electron transport.This study demonstrates a facile and favorable strategy to enhance the electrochemical performance of transition metal oxide electrode materials.
基金Program for Changjiang Scholars and Innovative Research Team in University (IRT0730)the Key Project of Department of Science and Technology of Jiangxi ProvinceProject of Education Department of Jiangxi
文摘Green light-emitting Ba2SiO4：Eu^2＋ phosphors co-doped with La or Y were synthesized by conventional solid-state reaction technique in reductive atmosphere（a mixture of 5% H2 and 95% N2）.The results showed that the co-doping of La and Y could greatly enhance the fluorescence intensity of Ba2SiO4：Eu2＋ phosphors.The optimum doping concentration expressed by the x value in（Ba0.985-1.5xREx）2SiO4：0.03Eu^2＋（RE=La or Y） was determined to be of 0.05.The excitation and emission peaks of all as-synthesized phosphors were wide bands.The excitation bands ranged from 250 to 400 nm, which matched well with the wavelength of near ultraviolet white light-emitting diodes（LED） chip and could be used as a potential candidate for the fabrication of white LED.The emission bands from 450 to 550 nm were typical 5d-4f transition emission of Eu^2＋ and displayed un-symmetry profiles because of the two substitution sites of Ba^2＋ with Eu^2＋.
基金supported by the National Natural Science Foundation of China(21573255,21573062)Natural Science Foundation of Liao Ning Province(20180510014)+1 种基金supported by Joint Research Fund Liaoning-Shenyang National Laboratory for Materials Science and the State Key Laboratory of Catalytic Materials and Reaction Engineering(RIPP,SINOPEC)supported by the Special Program for Applied Research on Super Computation of the NSFC Guangdong Joint Fund(the second phase)under Grant No.U1501501。
文摘Electrochemical reduction of CO_(2)(CERR)to value-added chemicals is an attractive strategy for greenhouse gas mitigation,and carbon recycles utilization.Conventional metal catalysts suffered from low durability and sluggish kinetics impede the practical application.On the other hand,doped carbon materials recently demonstrate superior catalytic performance in CERR,which shows the potential to diminish the problems of metal catalysts to some extent.Herein,we present the design and fabrication of nitrogen(N),phosphorus(P)co-doped metal-free carbon materials as an efficient and stable electrocatalyst for reduction of CO_(2) to CO,which exhibits an excellent performance with a high faradaic efficiency of 92%(-0.55 V vs.RHE)and up to 24 h stability.A series of characterizations including TEM and XPS verified that nitrogen and phosphorous are successfully incorporated into the carbon matrix.Moreover,the comparisons between co-doping and single doping catalysts reveal that co-doping can significantly increase CERR performance.The improved catalytic activity is attributed to the synergetic effects between nitrogen and phosphorous dopants,which effectively modulate properties of the active site.The density functional theory(DFT)calculations were also performed to understand the synergy effects of dopants.It is revealed that the phosphorous doping can significantly lower the Gibbs free energy of COOH^(*)formation.Moreover,the introduction of the second dopants phosphorous can reduce the reaction barrier along the reaction path and cause polarization of density of states at the Fermi level.These changes can greatly enhance the activity of the catalysts.From a combined experimental and computational exploration,current work provides valuable insights into the reaction mechanism of CERR on N,P co-doped carbon catalysts,and the influence from synergy effects between dopants,which paves the way for the rational design of novel metal-free catalysts for CO2 electro-reduction.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.10325415 and 50504017)the Natural Science Foundation of Hunan Province,China(Grant No.07JJ3102)+1 种基金the Scientific Research Fund of Hunan Provincial Education Department,China(Grant No.10C1171)the Science Development Foundation of Central South University,China(Grant Nos.08SDF02 and 09SDF09)
文摘Using the first-principles calculations, we investigate the electronic band structure and the quantum transport properties of metallic carbon nanotubes （MCNTs） with B/N pair co-doping. The results about formation energy show that the B/N pair co-doping configuration is a most stable structure. We find that the electronic structure and the transport properties are very sensitive to the doping concentration of the B/N pairs in MCNTs, where the energy gaps increase with doping concentration increasing both along the tube axis and around the tube, because the mirror symmetry of MCNT is broken by doping B/N pairs. In addition, we discuss conductance dips of the transmission spectrum of doped MCNTs. These unconventional doping effects could be used to design novel nanoelectronic devices.
