Seawater electrolysis is an effective way to obtain hydrogen(H_(2))in a sustainable manner.However,the lack of electrocatalysts with high activity,stability,and selectivity for oxygen evolution reaction(OER)severely h...Seawater electrolysis is an effective way to obtain hydrogen(H_(2))in a sustainable manner.However,the lack of electrocatalysts with high activity,stability,and selectivity for oxygen evolution reaction(OER)severely hinders the development of seawater electrolysis technology.Herein,sulfur-doped nickel-iron selenide nanosheets(S-NiFeSe_(2))were prepared by an ion-exchange strategy and served as highly active OER electrocatalyst for alkaline seawater electrolysis.The overpotential is 367 m V,and it can run stably for over 50 h at 100 m A cm^(-2).Excitingly,the S-NiFeSe_(2)||Pt/C pair exhibits cell voltage of 1.54 V at 10 m A cm^(-2)under alkaline seawater conditions,which can run smoothly for 100 h without decay,and the efficiency of electricity-tohydrogen(ETH)energy conversion reaches more than 80%.Such electrode,with abundant accessible reactive sites and good corrosion resistance,is a good candidate for seawater electrolysis.Moreover,density functional theory calculations reveal that the surface sulfur atoms can activate the adjacent Ni sites and decrease the free energy changes of the associated intermediates at the adjacent Ni sites for OER,and the step of~*OH→~*O is the potential rate-limiting step.In this work,the true reactive site in nickel-iron selenides is the Ni sites,but not the Fe sites as commonly believed.展开更多
Aqueous zinc ion batteries(AZIBs)have attracted much attention in recent years due to their high safety,low cost,and decent electrochemical performance.However,the traditional electrodes development process requires t...Aqueous zinc ion batteries(AZIBs)have attracted much attention in recent years due to their high safety,low cost,and decent electrochemical performance.However,the traditional electrodes development process requires tedious synthesis and testing procedures,which reduces the efficiency of developing highperformance battery devices.Here,we proposed a high-throughput screening strategy based on firstprinciples calculations to aid the experimental development of high-performance spinel cathode materials for AZIBs.We obtained 14 spinel materials from 12,047 Mn/Zn-O based materials by examining their structures and whether they satisfy the basic properties of electrodes.Then their band structures and density of states,open circuit voltage and volume expansion rate,ionic diffusion coefficient and energy barrier were further evaluated by first-principles calculations,resulting in five potential candidates.One of the promising candidates identified,Mg_(2)MnO_(4),was experimentally synthesized,characterized and integrated into an AZIB based cell to verify its performance as a cathode.The Mg_(2)MnO_(4)cathode exhibits excellent cycling stability,which is consistent with the theoretically predicted low volume expansion.Moreover,at high current density,the Mg_(2)MnO_(4)cathode still exhibits high reversible capacity and excellent rate performance,indicating that it is an excellent cathode material for AZIBs.Our work provides a new approach to accelerate the development of high-performance cathodes for AZIBs and other ion batteries.展开更多
Excitonic confinement greatly determines the charge carrier transport of photocatalysts.A molten salt modulation of excitonic con-finement is herein demonstrated as formation of ultrafine carbon-doped anatase TiO_(2)w...Excitonic confinement greatly determines the charge carrier transport of photocatalysts.A molten salt modulation of excitonic con-finement is herein demonstrated as formation of ultrafine carbon-doped anatase TiO_(2)with grafted graphitic carbon nitride,which is rationalized as an excellent catalyst for overall CO_(2)photoreduction.Compared with bulk TiO_(2),the carbon-doped TiO_(2)(M-TiO_(2))pos-sesses a weaker excitonic confinement to decrease exciton binding energy from 99 to 58 meV,consequently enhancing free-charge-carrier generation and transportation.Effective Z-scheme electron transfer from M-TiO_(2)to C_(3)N_(4) is built,enhancing the CO_(2)conversion via the synchronous optimization of redox ability,CO_(2)activation,and^(*)COOH generation.This work highlights the unique chemistry of excitonic dissociation on facilitating separation of electron and hole,and also extends the scope of molten salt-mediated modulation of photocatalysis materials.展开更多
This paper presents multiple-modes Scanning Probe Microscopy(SPM)studies on characterize the correlation of resistance switching(RS)and polarization rotation(PR)in copper doped ZnO(ZnO:Cu)thin films.Firstly,the bipola...This paper presents multiple-modes Scanning Probe Microscopy(SPM)studies on characterize the correlation of resistance switching(RS)and polarization rotation(PR)in copper doped ZnO(ZnO:Cu)thin films.Firstly,the bipolar RS behavior is confirmed by conductive Atomic Force Microscopy(c-AFM).The PR with almost 180phase angle is confirmed by using the Piezoresponse Force Microscopy(PFM)on the same location.In addition,it elucidates that obvious PR behavior can be observed in the sample with increasing Cu concentration by combining Kelvin Probe Force Microscopy(KPFM).Furthermore,it is found that the region with downward polarization has low resistance state(LRS),whereas the region with upward polarization has high resistance state(HRS).Moreover,the Piezoresponse Force Spectroscopy(PFS)and Switching Spectroscopy PFM(SS-PFM)measurements further confirm that the existence of the built-in voltage,V_(built-in) is largest in the ZnO:Cu(8 at.%)film deposited at the oxygen partial pressure of 2×10^(-4) Torr.The schematic diagrams of energy band diagram with varied built-in field,Ebuilt-in,polarization directions and redistributed charges are presented to explain the correlation between RS and PR behavior.展开更多
基金supported by the National Natural Science Foundation of China(22202053,22109035,52274297)the Startup Research Foundation of Hainan University(KYQD(ZR)-20008,20083,20084,21125,23170)+3 种基金the specific research fund of the Innovation Platform for Academicians of Hainan Province(YSPTZX202315)the Research Fund Program of Guangdong Provincial Key Laboratory of Fuel Cell Technology(FC202307)the Open Fund Project of Key Laboratory of Electrochemical Energy Storage and Energy Conversion in Hainan Province of China(KFKT2023002)the Innovative Research Projects for Graduate Students of Hainan Province(Qhyb2023-15)。
文摘Seawater electrolysis is an effective way to obtain hydrogen(H_(2))in a sustainable manner.However,the lack of electrocatalysts with high activity,stability,and selectivity for oxygen evolution reaction(OER)severely hinders the development of seawater electrolysis technology.Herein,sulfur-doped nickel-iron selenide nanosheets(S-NiFeSe_(2))were prepared by an ion-exchange strategy and served as highly active OER electrocatalyst for alkaline seawater electrolysis.The overpotential is 367 m V,and it can run stably for over 50 h at 100 m A cm^(-2).Excitingly,the S-NiFeSe_(2)||Pt/C pair exhibits cell voltage of 1.54 V at 10 m A cm^(-2)under alkaline seawater conditions,which can run smoothly for 100 h without decay,and the efficiency of electricity-tohydrogen(ETH)energy conversion reaches more than 80%.Such electrode,with abundant accessible reactive sites and good corrosion resistance,is a good candidate for seawater electrolysis.Moreover,density functional theory calculations reveal that the surface sulfur atoms can activate the adjacent Ni sites and decrease the free energy changes of the associated intermediates at the adjacent Ni sites for OER,and the step of~*OH→~*O is the potential rate-limiting step.In this work,the true reactive site in nickel-iron selenides is the Ni sites,but not the Fe sites as commonly believed.
基金This work was financially supported by research grants from the Natural Science Foundation of China(Nos.12004057,62074022,52173235)Support plan for Overseas Students to Return to China for Entrepreneurship and Innovation(No.cx2020075)+3 种基金Open Fund of Key Laboratory of Low-grade Energy Utilization Technologies and Systems(No.LLEUTS-2020008)Chongqing Funds for Distinguished Young Scientists(No.cstc2021jcyj-jqX0015)Chongqing Talent Plan(No.CQYC2021059206)Fundamental Research Funds for the Central Universities(No.2020CDJQY-A055).
文摘Aqueous zinc ion batteries(AZIBs)have attracted much attention in recent years due to their high safety,low cost,and decent electrochemical performance.However,the traditional electrodes development process requires tedious synthesis and testing procedures,which reduces the efficiency of developing highperformance battery devices.Here,we proposed a high-throughput screening strategy based on firstprinciples calculations to aid the experimental development of high-performance spinel cathode materials for AZIBs.We obtained 14 spinel materials from 12,047 Mn/Zn-O based materials by examining their structures and whether they satisfy the basic properties of electrodes.Then their band structures and density of states,open circuit voltage and volume expansion rate,ionic diffusion coefficient and energy barrier were further evaluated by first-principles calculations,resulting in five potential candidates.One of the promising candidates identified,Mg_(2)MnO_(4),was experimentally synthesized,characterized and integrated into an AZIB based cell to verify its performance as a cathode.The Mg_(2)MnO_(4)cathode exhibits excellent cycling stability,which is consistent with the theoretically predicted low volume expansion.Moreover,at high current density,the Mg_(2)MnO_(4)cathode still exhibits high reversible capacity and excellent rate performance,indicating that it is an excellent cathode material for AZIBs.Our work provides a new approach to accelerate the development of high-performance cathodes for AZIBs and other ion batteries.
基金funding support from the National Natural Science Foundation of China(22272120,U2202251,92045302)the Fundamental Research Funds for the Central Universities(2042022kf1174,2042021kf0213)+1 种基金the Hainan Province Science and Technology Special Fund(ZDYF2021SHFZ058,ZDYF2020207)the High-level Talent Project of Hainan Natural Science Foundation(2019RC075).
文摘Excitonic confinement greatly determines the charge carrier transport of photocatalysts.A molten salt modulation of excitonic con-finement is herein demonstrated as formation of ultrafine carbon-doped anatase TiO_(2)with grafted graphitic carbon nitride,which is rationalized as an excellent catalyst for overall CO_(2)photoreduction.Compared with bulk TiO_(2),the carbon-doped TiO_(2)(M-TiO_(2))pos-sesses a weaker excitonic confinement to decrease exciton binding energy from 99 to 58 meV,consequently enhancing free-charge-carrier generation and transportation.Effective Z-scheme electron transfer from M-TiO_(2)to C_(3)N_(4) is built,enhancing the CO_(2)conversion via the synchronous optimization of redox ability,CO_(2)activation,and^(*)COOH generation.This work highlights the unique chemistry of excitonic dissociation on facilitating separation of electron and hole,and also extends the scope of molten salt-mediated modulation of photocatalysis materials.
基金supported by the Start-up Research Foundation of Hainan University[grant no.KYQD(ZR)1816]the support from Ministry of Education,Singapore,through National University of Singapore(NUS)under the Academic Research Fund(grant no.R265-000-496-112).
文摘This paper presents multiple-modes Scanning Probe Microscopy(SPM)studies on characterize the correlation of resistance switching(RS)and polarization rotation(PR)in copper doped ZnO(ZnO:Cu)thin films.Firstly,the bipolar RS behavior is confirmed by conductive Atomic Force Microscopy(c-AFM).The PR with almost 180phase angle is confirmed by using the Piezoresponse Force Microscopy(PFM)on the same location.In addition,it elucidates that obvious PR behavior can be observed in the sample with increasing Cu concentration by combining Kelvin Probe Force Microscopy(KPFM).Furthermore,it is found that the region with downward polarization has low resistance state(LRS),whereas the region with upward polarization has high resistance state(HRS).Moreover,the Piezoresponse Force Spectroscopy(PFS)and Switching Spectroscopy PFM(SS-PFM)measurements further confirm that the existence of the built-in voltage,V_(built-in) is largest in the ZnO:Cu(8 at.%)film deposited at the oxygen partial pressure of 2×10^(-4) Torr.The schematic diagrams of energy band diagram with varied built-in field,Ebuilt-in,polarization directions and redistributed charges are presented to explain the correlation between RS and PR behavior.
