利用可再生能源发电,并通过低温电解水技术生产氢气,被认为是一种环保且可持续的制氢途径,是未来氢能发展的重要方向之一.采用该方法生产的氢气因其环保特性而被称为“绿氢”.然而,目前绿氢高昂的生产成本限制了电解水制氢技术的大规模...利用可再生能源发电,并通过低温电解水技术生产氢气,被认为是一种环保且可持续的制氢途径,是未来氢能发展的重要方向之一.采用该方法生产的氢气因其环保特性而被称为“绿氢”.然而,目前绿氢高昂的生产成本限制了电解水制氢技术的大规模应用.因此,开发先进的非贵金属催化剂和电催化体系以降低电解水制氢成本具有重要意义.界面工程是一种提升非贵金属催化剂电解水性能的有效策略,但目前对其催化活性位点的识别及活性提升机制的研究仍然不足.本文采用简单的水热及低温磷化法制备了具有丰富异质界面的Ni_(2)P/CoP/FeP_(4)/IF催化剂,并研究了其在电解水过程中的催化活性位点及这些位点在提升催化能力方面的协同作用.采用扫描电镜(SEM)证明了Ni_(2)P/CoP/FeP_(4)/IF催化剂呈现纳米线网络结构,这种结构不仅有利于增加催化剂的电化学活性位点和加速反应动力学,而且促进了连续产生的气泡从活性位点逃逸,从而提高了催化剂的机械稳定性.电化学研究结果表明,所制备Ni_(2)P/CoP/FeP_(4)/IF催化剂在1.0 mol L^(‒1)KOH溶液中表现出较好的析氧反应(OER)和析氢反应(HER)活性,分别仅需218和127 mV的过电位,即可达到100 mA cm^(‒2)的电流密度.将Ni_(2)P/CoP/FeP_(4)/IF分别作为阴极和阳极构建双电极电解槽,该装置产生100和500 mA cm^(‒2)的电流密度分别仅需1.68和2.05 V的电压,这一性能优于大多数已报道的自支撑过渡金属磷化物催化剂.多步计时电位测试结果进一步证实了Ni_(2)P/CoP/FeP_(4)/IF作为阳极和阴极材料在水分解过程中具有较好的长期耐久性.X射线光电子能谱和差分电荷分析表明,电子从富电子的FeP_(4)向缺电子的Ni_(2)P和CoP转移,这促使Ni_(2)P和CoP上的电子积累和FeP_(4)上的空穴积累,有利于优化反应中间体的吸附和脱附自由能,提升OER和HER催化性能.结合X射线衍射、扫描电镜、透射电镜、X射线光电子能谱和原位拉曼光谱结果发现,催化剂重构后形成的特定(氧)氢氧化物结构,是OER反应真正的关键活性位点.原位拉曼光谱进一步证实了异质界面促进了OER过程中Ni_(2)P/CoP/FeP_(4)/IF的快速重构.此外,利用密度泛函理论分析了催化剂的HER反应机理.计算结果表明,H2O优先吸附在Fe位点并发生水解,随后产生的H*吸附在Ni位点上并发生解吸,从而促进了催化剂中Fe和Ni活性位点的高效利用.同时,CoP的引入提高了Ni_(2)P/CoP/FeP_(4)/IF催化剂的水吸附和解离能力,进一步提升了其HER活性.综上所述,本文通过简单的水热及低温磷化法制备了具有丰富异质界面的Ni_(2)P/CoP/FeP_(4)/IF过渡金属磷化物纳米线网络催化剂,并将其用于碱性水分解.通过多种表征技术及理论计算结果分析,识别了电解水过程中的关键催化活性位点,即催化剂重构后形成的特定(氧)氢氧化物结构,并揭示了其在OER和HER反应中的催化机制.本研究可为高性能碱性电解水催化剂的理性设计和开发提供参考.展开更多
Tackling the problem of poor conductivity and catalytic stability of pristine metal-organic frameworks(MOFs) is crucial to improve their oxygen evolution reaction(OER) performance.Herein,we introduce a novel strategy ...Tackling the problem of poor conductivity and catalytic stability of pristine metal-organic frameworks(MOFs) is crucial to improve their oxygen evolution reaction(OER) performance.Herein,we introduce a novel strategy of dysprosium(Dy) doping,using the unique 4f orbitals of this rare earth element to enhance electrocatalytic activity of MOFs.Our method involves constructing Dy-doped Ni-MOF(Dy@Ni-MOF) nanoneedles on carbon cloth via a Dy-induced valence electronic perturbation approach.Experiments and density functional theory(DFT) calculations reveal that Dy doping can effectively modify the electronic structure of the Ni active centers and foster a strong electronic interaction between Ni and Dy.The resulting benefits include a reduced work function and a closer proximity of the d-band center to the Fermi level,which is conducive to improving electrical conductivity and promoting the adsorption of oxygen-containing intermediates.Furthermore,the Dy@Ni-MOF achieves superhydrophilicity,ensuring effective electrolyte contact and thus accelerating reaction kinetics,Ex-situ and in-situ analysis results manifest Dy_(2)O_(3)/NiOOH as the actual active species.Therefore,Dy@Ni-MOF shows impressive OER performance,significantly surpassing Ni-MOF.Besides,the overall water splitting device with Dy@NiMOF as an anode delivers a low cell voltage of 1.51 V at 10 mA cm^(-2) and demonstrates long-term stability for 100 h,positioning it as a promising substitute for precious metal catalysts.展开更多
Continuous efforts are underway to reduce carbon emissions worldwide in response to global climate change.Water electrolysis technology,in conjunction with renewable energy,is considered the most feasible hydrogen pro...Continuous efforts are underway to reduce carbon emissions worldwide in response to global climate change.Water electrolysis technology,in conjunction with renewable energy,is considered the most feasible hydrogen production technology based on the viable possibility of large-scale hydrogen production and the zero-carbon-emission nature of the process.However,for hydrogen produced via water electrolysis systems to be utilized in various fields in practice,the unit cost of hydrogen production must be reduced to$1/kg H_(2).To achieve this unit cost,technical targets for water electrolysis have been suggested regarding components in the system.In this paper,the types of water electrolysis systems and the limitations of water electrolysis system components are explained.We suggest guideline with recent trend for achieving this technical target and insights for the potential utilization of water electrolysis technology.展开更多
文摘利用可再生能源发电,并通过低温电解水技术生产氢气,被认为是一种环保且可持续的制氢途径,是未来氢能发展的重要方向之一.采用该方法生产的氢气因其环保特性而被称为“绿氢”.然而,目前绿氢高昂的生产成本限制了电解水制氢技术的大规模应用.因此,开发先进的非贵金属催化剂和电催化体系以降低电解水制氢成本具有重要意义.界面工程是一种提升非贵金属催化剂电解水性能的有效策略,但目前对其催化活性位点的识别及活性提升机制的研究仍然不足.本文采用简单的水热及低温磷化法制备了具有丰富异质界面的Ni_(2)P/CoP/FeP_(4)/IF催化剂,并研究了其在电解水过程中的催化活性位点及这些位点在提升催化能力方面的协同作用.采用扫描电镜(SEM)证明了Ni_(2)P/CoP/FeP_(4)/IF催化剂呈现纳米线网络结构,这种结构不仅有利于增加催化剂的电化学活性位点和加速反应动力学,而且促进了连续产生的气泡从活性位点逃逸,从而提高了催化剂的机械稳定性.电化学研究结果表明,所制备Ni_(2)P/CoP/FeP_(4)/IF催化剂在1.0 mol L^(‒1)KOH溶液中表现出较好的析氧反应(OER)和析氢反应(HER)活性,分别仅需218和127 mV的过电位,即可达到100 mA cm^(‒2)的电流密度.将Ni_(2)P/CoP/FeP_(4)/IF分别作为阴极和阳极构建双电极电解槽,该装置产生100和500 mA cm^(‒2)的电流密度分别仅需1.68和2.05 V的电压,这一性能优于大多数已报道的自支撑过渡金属磷化物催化剂.多步计时电位测试结果进一步证实了Ni_(2)P/CoP/FeP_(4)/IF作为阳极和阴极材料在水分解过程中具有较好的长期耐久性.X射线光电子能谱和差分电荷分析表明,电子从富电子的FeP_(4)向缺电子的Ni_(2)P和CoP转移,这促使Ni_(2)P和CoP上的电子积累和FeP_(4)上的空穴积累,有利于优化反应中间体的吸附和脱附自由能,提升OER和HER催化性能.结合X射线衍射、扫描电镜、透射电镜、X射线光电子能谱和原位拉曼光谱结果发现,催化剂重构后形成的特定(氧)氢氧化物结构,是OER反应真正的关键活性位点.原位拉曼光谱进一步证实了异质界面促进了OER过程中Ni_(2)P/CoP/FeP_(4)/IF的快速重构.此外,利用密度泛函理论分析了催化剂的HER反应机理.计算结果表明,H2O优先吸附在Fe位点并发生水解,随后产生的H*吸附在Ni位点上并发生解吸,从而促进了催化剂中Fe和Ni活性位点的高效利用.同时,CoP的引入提高了Ni_(2)P/CoP/FeP_(4)/IF催化剂的水吸附和解离能力,进一步提升了其HER活性.综上所述,本文通过简单的水热及低温磷化法制备了具有丰富异质界面的Ni_(2)P/CoP/FeP_(4)/IF过渡金属磷化物纳米线网络催化剂,并将其用于碱性水分解.通过多种表征技术及理论计算结果分析,识别了电解水过程中的关键催化活性位点,即催化剂重构后形成的特定(氧)氢氧化物结构,并揭示了其在OER和HER反应中的催化机制.本研究可为高性能碱性电解水催化剂的理性设计和开发提供参考.
基金supported by the National Natural Science Foundation of China(52363028,21965005)the Natural Science Foundation of Guangxi Province(2021GXNSFAA076001)the Guangxi Technology Base and Talent Subject(GUIKE AD18126001,GUIKE AD20297039)。
文摘Tackling the problem of poor conductivity and catalytic stability of pristine metal-organic frameworks(MOFs) is crucial to improve their oxygen evolution reaction(OER) performance.Herein,we introduce a novel strategy of dysprosium(Dy) doping,using the unique 4f orbitals of this rare earth element to enhance electrocatalytic activity of MOFs.Our method involves constructing Dy-doped Ni-MOF(Dy@Ni-MOF) nanoneedles on carbon cloth via a Dy-induced valence electronic perturbation approach.Experiments and density functional theory(DFT) calculations reveal that Dy doping can effectively modify the electronic structure of the Ni active centers and foster a strong electronic interaction between Ni and Dy.The resulting benefits include a reduced work function and a closer proximity of the d-band center to the Fermi level,which is conducive to improving electrical conductivity and promoting the adsorption of oxygen-containing intermediates.Furthermore,the Dy@Ni-MOF achieves superhydrophilicity,ensuring effective electrolyte contact and thus accelerating reaction kinetics,Ex-situ and in-situ analysis results manifest Dy_(2)O_(3)/NiOOH as the actual active species.Therefore,Dy@Ni-MOF shows impressive OER performance,significantly surpassing Ni-MOF.Besides,the overall water splitting device with Dy@NiMOF as an anode delivers a low cell voltage of 1.51 V at 10 mA cm^(-2) and demonstrates long-term stability for 100 h,positioning it as a promising substitute for precious metal catalysts.
基金supported by the Korea Institute of Energy Technology Evaluation and Planning(KETEP)grant from the Ministry of Trade,Industry&Energy,Republic of Korea(No.20213030040590)the National R&D Program through the National Research Foundation of Korea(NRF)funded by the Ministry of Science and ICT(NRF-2021K1A4A8A01079455)。
文摘Continuous efforts are underway to reduce carbon emissions worldwide in response to global climate change.Water electrolysis technology,in conjunction with renewable energy,is considered the most feasible hydrogen production technology based on the viable possibility of large-scale hydrogen production and the zero-carbon-emission nature of the process.However,for hydrogen produced via water electrolysis systems to be utilized in various fields in practice,the unit cost of hydrogen production must be reduced to$1/kg H_(2).To achieve this unit cost,technical targets for water electrolysis have been suggested regarding components in the system.In this paper,the types of water electrolysis systems and the limitations of water electrolysis system components are explained.We suggest guideline with recent trend for achieving this technical target and insights for the potential utilization of water electrolysis technology.
