The conversion of urea-containing wastewater into clean hydrogen energy has gained increasing attention.However,challenges remain,particularly with sluggish catalytic kinetics and limited long-term stability of urea o...The conversion of urea-containing wastewater into clean hydrogen energy has gained increasing attention.However,challenges remain,particularly with sluggish catalytic kinetics and limited long-term stability of urea oxidation reaction(UOR).Herein,we report the loosely porous CoOOH nano-architecture(CoOOH LPNAs)with hydrophilic surface and abundant oxygen vacancies(Ov)on carbon fiber paper(CFP)by electrochemical reconstruction of the CoP nanoneedles precursor.The resulting three-dimensional electrode exhibited an impressively low potential of 1.38 V at 1000 mA·cm^(−2) and excellent durability for UOR.Furthermore,when tested in an anion exchange membrane(AEM)electrolyzer,it required only 1.53 V at 1000 mA·cm^(−2) for industrial urea-assisted water splitting and operated stably for 100 h without degrada-tion.Experimental and theoretical investigations revealed that rich oxygen vacancies effectively modulate the electronic structure of the CoOOH while creating unique Co3-triangle sites with Co atoms close together.As a result,the adsorption and desorption processes of reactants and intermediates in UOR could be finely tuned,thereby significantly reducing ther-modynamic barriers.Additionally,the superhydrophilic self-supported nanoarray structure facilitated rapid gas bubble release,improving the overall efficiency of the reaction and preventing potential catalyst detachment caused by bubble accumulation,thereby improving both catalytic activity and stability at high current densities.展开更多
Metal oxohydroxides(MOOH) are widely accepted as the true active species for oxygen evolution reaction(OER).However,the MOOH converted from precatalysts usually exhibits better catalytic performance than those directl...Metal oxohydroxides(MOOH) are widely accepted as the true active species for oxygen evolution reaction(OER).However,the MOOH converted from precatalysts usually exhibits better catalytic performance than those directly synthesized.The underlying structural reason for this phenomenon remains controversial.In this work,CoOOH and Co(OH)2with similar morphology are employed as model catalysts to investigate the origin of in-situ converted catalyst s high activity,as Co(OH)2can be fully converted to CoOOH during OER.In-situ Raman,electron paramagnetic resonance,HR-TEM,and X-ray spectroscopic studies reveal that O vacancies in the CoOOH converted from Co(OH)2play a key role in its higher intrinsic activity towards OER than directly synthesized CoOOH.Furthermore,theoretical calculations and electrochemical methods indicate that O vacancies in CoOOH affect the interaction between Co-O bond,downshift the d-band center of Co,further weaken the adsorption of OH*,and finally facilitate the OER process over CoOOH.This work not only provides a deep understanding of pre-catalyst's high OER activity by taking Co(OH)2as an example but also deliver insights into the activation process of other electrochemic al oxidation reactions.展开更多
Different sizes of layered CoOOH were synthesized by the molten-salt-assisted method at different temperatures.X-ray diffraction and scanning electron microscope studies reveal that CoOOH grew at(003)with increasing t...Different sizes of layered CoOOH were synthesized by the molten-salt-assisted method at different temperatures.X-ray diffraction and scanning electron microscope studies reveal that CoOOH grew at(003)with increasing temperature,and its size can reach dozens of microns.X-ray absorption near edge structure and XPS studies demonstrate that the Co valence state of CoOOH-750 is trivalent,and X-ray Absorption Fine Structure shows that it had a higher symmetry and lower disorder degree,indicating that CoOOH-750 has higher crystallinity and Co3+.The results of electrochemical tests show that CoOOH-750 exhibited the best oxygen-evolution-reaction(OER)catalytic activity.展开更多
Transition-metal oxyhydroxides are attractive catalysts for oxygen evolution reactions(OERs).Further studies for developing transition-metal oxyhydroxide catalysts and understanding their catalytic mechanisms will ben...Transition-metal oxyhydroxides are attractive catalysts for oxygen evolution reactions(OERs).Further studies for developing transition-metal oxyhydroxide catalysts and understanding their catalytic mechanisms will benefit their quick transition to the next catalysts.Herein,Mo-doped CoOOH was designed as a high-performance model electrocatalyst with durability for 20 h at 10 mAcm−2.Additionally,it had an overpotential of 260 mV(glassy carbon)or 215 mV(nickel foam),which was 78 mV lower than that of IrO_(2)(338 mV).In situ,Raman spectroscopy revealed the transformation process of CoOOH.Calculations using the density functional theory showed that during OER,doped Mo increased the spin-up density of states and shrank the spin-down bandgap of the 3d orbits in the reconstructed CoOOH under the electrochemical activation process,which simultaneously optimized the adsorption and electron conduction of oxygen-related intermediates on Co sites and lowered the OER overpotentials.Our research provides new insights into the methodical planning of the creation of transition-metal oxyhydroxide OER catalysts.展开更多
基金supported by the Applied Basic Research Program of Yunnan Province(202101BE070001-032)Yunnan Major Scientific and Technological Projects(No.202202AG050001).
文摘The conversion of urea-containing wastewater into clean hydrogen energy has gained increasing attention.However,challenges remain,particularly with sluggish catalytic kinetics and limited long-term stability of urea oxidation reaction(UOR).Herein,we report the loosely porous CoOOH nano-architecture(CoOOH LPNAs)with hydrophilic surface and abundant oxygen vacancies(Ov)on carbon fiber paper(CFP)by electrochemical reconstruction of the CoP nanoneedles precursor.The resulting three-dimensional electrode exhibited an impressively low potential of 1.38 V at 1000 mA·cm^(−2) and excellent durability for UOR.Furthermore,when tested in an anion exchange membrane(AEM)electrolyzer,it required only 1.53 V at 1000 mA·cm^(−2) for industrial urea-assisted water splitting and operated stably for 100 h without degrada-tion.Experimental and theoretical investigations revealed that rich oxygen vacancies effectively modulate the electronic structure of the CoOOH while creating unique Co3-triangle sites with Co atoms close together.As a result,the adsorption and desorption processes of reactants and intermediates in UOR could be finely tuned,thereby significantly reducing ther-modynamic barriers.Additionally,the superhydrophilic self-supported nanoarray structure facilitated rapid gas bubble release,improving the overall efficiency of the reaction and preventing potential catalyst detachment caused by bubble accumulation,thereby improving both catalytic activity and stability at high current densities.
基金financially supported by the financial support from Natural Science Foundation of China(No.22209129)the High-Level Innovation and Entrepreneurship Talent Project of Qinchuangyuan(No.QCYRCXM-2022-123)+3 种基金the Innovation Capability Support Program of Shaanxi(No.2023-CXTD-26)the financial support from the"Young Talent Support Plan''of Xi'an Jiaotong University(No.HG6J024)the financial support from China Postdoctoral Science Foundation 2024M752560Postdoctoral Fellowship Program of CPSF under Grant Number GZB20230574
文摘Metal oxohydroxides(MOOH) are widely accepted as the true active species for oxygen evolution reaction(OER).However,the MOOH converted from precatalysts usually exhibits better catalytic performance than those directly synthesized.The underlying structural reason for this phenomenon remains controversial.In this work,CoOOH and Co(OH)2with similar morphology are employed as model catalysts to investigate the origin of in-situ converted catalyst s high activity,as Co(OH)2can be fully converted to CoOOH during OER.In-situ Raman,electron paramagnetic resonance,HR-TEM,and X-ray spectroscopic studies reveal that O vacancies in the CoOOH converted from Co(OH)2play a key role in its higher intrinsic activity towards OER than directly synthesized CoOOH.Furthermore,theoretical calculations and electrochemical methods indicate that O vacancies in CoOOH affect the interaction between Co-O bond,downshift the d-band center of Co,further weaken the adsorption of OH*,and finally facilitate the OER process over CoOOH.This work not only provides a deep understanding of pre-catalyst's high OER activity by taking Co(OH)2as an example but also deliver insights into the activation process of other electrochemic al oxidation reactions.
文摘利用工艺简单,成本低廉的共沉淀法制得Co OOH,并用作非水性锂-氧气电池阴极催化剂。通过恒流充放电、线性伏安扫描(LSV)和电化学阻抗(EIS)测试研究了电极的电化学性能。结果表明:由于Co OOH能够明显提高氧气还原反应(ORR)的催化活性,与未使用Co OOH的电极相比较,使用Co OOH为催化剂的电极首次放电容量高达5 093 m Ah·g^(-1),提高了1.7倍。电池的充电过电压降低了约460 m V,充电可逆性得到增强,充放电可逆性提高,使得循环性能得到显著改善。
基金This work was supported by“Transformational Technologies for Clean Energy and Demonstration”,Strategic Priority Research Program of the Chinese Academy of Sciences(Grant no.XDA21080200).
文摘Different sizes of layered CoOOH were synthesized by the molten-salt-assisted method at different temperatures.X-ray diffraction and scanning electron microscope studies reveal that CoOOH grew at(003)with increasing temperature,and its size can reach dozens of microns.X-ray absorption near edge structure and XPS studies demonstrate that the Co valence state of CoOOH-750 is trivalent,and X-ray Absorption Fine Structure shows that it had a higher symmetry and lower disorder degree,indicating that CoOOH-750 has higher crystallinity and Co3+.The results of electrochemical tests show that CoOOH-750 exhibited the best oxygen-evolution-reaction(OER)catalytic activity.
基金The National Natural Science Foundation of China(Grant Nos.52072114 and 51922008)the 111 Project(Grant No.D17007),the Henan Center for Outstanding Overseas Scientists(Grant No.GZS2018003)+2 种基金Xinxiang Major Science and Technology Projects(Grant No.21ZD001)Guangdong Innovative and Entrepreneurial Research Team Program(2016ZT06N500)Guangdong Provincial Key Laboratory of Energy Materials for Electric Power(2018B030322001)all provided financial support for this work.
文摘Transition-metal oxyhydroxides are attractive catalysts for oxygen evolution reactions(OERs).Further studies for developing transition-metal oxyhydroxide catalysts and understanding their catalytic mechanisms will benefit their quick transition to the next catalysts.Herein,Mo-doped CoOOH was designed as a high-performance model electrocatalyst with durability for 20 h at 10 mAcm−2.Additionally,it had an overpotential of 260 mV(glassy carbon)or 215 mV(nickel foam),which was 78 mV lower than that of IrO_(2)(338 mV).In situ,Raman spectroscopy revealed the transformation process of CoOOH.Calculations using the density functional theory showed that during OER,doped Mo increased the spin-up density of states and shrank the spin-down bandgap of the 3d orbits in the reconstructed CoOOH under the electrochemical activation process,which simultaneously optimized the adsorption and electron conduction of oxygen-related intermediates on Co sites and lowered the OER overpotentials.Our research provides new insights into the methodical planning of the creation of transition-metal oxyhydroxide OER catalysts.
