物理化学学报2023，Vol.39Issue(4)：48-57,10.DOI:10.3866/PKU.WHXB202301023
NiMo(O)物相结构与电解水析氢反应活性的关联
Relation between NiMo(O)Phase Structures and Hydrogen Evolution Activities of Water Electrolysis
摘要
Abstract
NiMo(O)catalysts show extremely low overpotential at high current density for the electrocatalytic hydrogen evolution reaction(HER).However,the real reason for the remarkable electrocatalytic activity is unclear.A new perspective for revealing the relation between the phase structures of the electrocatalysts and their electrocatalytic HER performance provides a deep insight into the nature of the HER.Herein,the dehydration and oxygenation of as-synthesized nickel molybdate hydrate(NiMoO4·nH2O)are discussed and confirmed to be critical for evolving the catalytic phase structures in the subsequent reduction treatment.The typical phase evolution processes of the electrocatalysts were investigated using thermogravimetric(TG)analysis and H2 temperature-programmed reduction(H2-TPR).The crystalline phases were identified through X-ray diffraction(XRD),Raman spectroscopy,and high-resolution transmission electron microscopy(HRTEM)analyses.The phases of the electrocatalysts during the electrochemical tests were confirmed by in situ electrochemical XRD characterization.Three typical crystalline phases,MoNi4,β-NiMoO4,and α-NiMoO4,corresponding to significantly different HER activities,were proposed.The β-NiMoO4 dominant electrocatalyst(NiMoO4-400air-H2)exhibited the worst performance for alkaline water reduction,and an improvement was observed for the a-NiMoO4 electrocatalyst(NiMoO4-500air-H2).The NiMoO4-300air-H2 electrode derived from NiMoO4·(n-x)H2O exhibited the most active phase(MoNi4)and the best electrocatalytic HER performance.Moreover,the intrinsic electrocatalytic HER performance obtained from the electrochemical active surface area(ECSA)normalized activities exhibits the same tendency as the geometrically normalized ones.Varied adsorption capacities of the H2O,OH,and H intermediate species for water reduction on these typical phases are assumed to be responsible for the significantly different HER performance of the NiMoO4-(T)air-H2 electrodes through density functional theory analysis.Poor adsorption of H,OH radicals,and H2O on β-NiMoO4 impedes the water dissociation process,which may be the reason that it exhibits the worst electrocatalytic hydrogen evolution activity.Optimized adsorption abilities of H,OH,and H2O on a-NiMoO4 benefit the water reduction kinetics,leading to an enhanced electrocatalytic HER performance.MoNi4 forms the strongest interactions with H2O,H,and OH species,contributing to the best electrocatalytic hydrogen evolution activity.Further analysis of the energy barrier of the water-splitting reaction shows that these three crystalline phases exhibit different water dissociation ability,which is attributed to their varied adsorption capacities of the intermediate species for water reduction.Among them,MoNi4 and β-NiMoO4 exhibit the lowest and highest water dissociation barriers,respectively,in line with their electrocatalytic hydrogen evolution activities.The phase-dependent HER activity identified in this work can provide guidelines for rationally designing and adjusting the structures of active NiMo(O)electrocatalysts.关键词
电催化/分解水/氢气/钼酸镍,物相Key words
Electrocatalysis/Water splitting/Hydrogen/Nickel molybdate/Crystalline Phase分类
化学化工引用本文复制引用
王奥琦,陈军,张鹏飞,唐珊,冯兆池,姚婷婷,李灿..NiMo(O)物相结构与电解水析氢反应活性的关联[J].物理化学学报,2023,39(4):48-57,10.基金项目
This work was conducted by the Fundamental Research Center of Artificial Photosynthesis,China(FReCAP),financially supported by the National Key R&D Program of China(2021YFB4000300),National Natural Science Foundation of China(22088102),Jointly Funded Project of NSFC(U20B6002),the Major Program of Liaoning Province,China(2022JH1/10400020).人工光合成基础科学中心(FReCAP),国家重点研发计划(2021YFB4000300),国家自然科学基金(22088102),基金委联合基金项目(U20B6002),辽宁省重大专项(2022JH1/10400020)资助项目 （FReCAP）
