Electrochemical partial reduction of Ni(OH)_(2) to Ni(OH)_(2)/Ni via coupled oxidation of an interfacing NiAl intermetallic compound for robust hydrogen evolution

作     者：Young Hwa Yun Kwangsoo Kim Changsoo Lee Byeong-Seon An Ji Hee Kwon Sechan Lee MinJoong Kim Jongsu Seo Jong Hyeok Park Byung-Hyun Kim Hyun-Seok Cho Young Hwa Yun;Kwangsoo Kim;Changsoo Lee;Byeong-Seon An;Ji Hee Kwon;Sechan Lee;MinJoong Kim;Jongsu Seo;Jong Hyeok Park;Byung-Hyun Kim;Hyun-Seok Cho

作者机构：Hydrogen Research DepartmentKorea Institute of Energy Research152 Gajeong-roYuseong-guDaejeon 34129Republic of Korea Computational Science&Engineering LaboratoryKorea Institute of Energy Research152 Gajeong-roYuseong-guDaejeon 34129Republic of Korea Analysis Center for Energy ResearchKorea Institute of Energy Research152 Gajeong-roYuseong-guDaejeon 34129Republic of Korea Department of Chemical and Biomolecular EngineeringYonsei University50 Yonsei-roSeodaemun-guSeoul 03722Republic of Korea 

出 版 物：《Journal of Energy Chemistry》 (能源化学（英文版）)

年 卷 期：2023年第82卷第7期

页      面：560-571,I0012页

核心收录：

学科分类：0808[工学-电气工程] 081705[工学-工业催化] 0806[工学-冶金工程] 08[工学] 0817[工学-化学工程与技术] 0804[工学-仪器科学与技术] 0703[理学-化学] 0702[理学-物理学] 

基　　金：supported by a Korea Evaluation Institute of Industrial Technology(KEIT)grant funded by the Korean government(MOTIE)(No.20022449) Commercialization Promotion Agency for R&D Outcomes(COMPA)grant funded by the Korean government(MSIT)(No.2021E100) supported by the Korea Electric Power Corporation(KEPCO),Open R&D(R22X004) the National Institute of Supercomputing and Network/Korea Institute of Science and Technology Information,which provided supercomputing resources,including technical support(KSC-2021-CRE-0568) 

主　　题：Raney nickel HERChemical leaching Intrinsic activity Partial reduction 

摘      要：Ni-based porous electrocatalysts have been widely used in the hydrogen evolution reaction(HER)in alkaline water electrolysis,and the catalysts are produced by selective leaching of Al from Ni-Al *** is well known that chemical leaching of Ni-Al intermetallic compound(IMC)generates a high surface area in Ni(OH)_(2).However,the Ni(OH)_(2) produced by leaching the Ni-Al intermetallic compound retards the hydrogen evolution reaction,which is attributed to its weak hydrogen adsorption *** this study,we controlled the chemical state of Ni using plasma vapor deposition(PVD)followed by heat treatment,selective Al leaching,and electrochemical reduction.X-ray diffraction(XRD),scanning microscopy(SEM),transmission electron microscopy(TEM),and energy-dispersive X-ray spectroscopy(EDS)were used to confirm the phase evolution of the electrocatalysts during *** reveal that the heat-treated Ni-Al alloy with a thick Ni2Al3surface layer underwent selective Al leaching and produced biphasic interfaces comprising Ni(OH)_(2) and NiAl IMCs at the edges of the grains in the outermost surface *** oxidation of the interfacing NiAl IMCs facilitated the partial reduction of Ni(OH)_(2) to Ni(OH)_(2)/Ni in the grains during electrochemical reduction,as confirmed by X-ray photoelectron spectroscopy(XPS).An electrocatalyst containing partially reduced Ni(OH)_(2)/Ni exhibited an overpotential of 54 mV at 10 mA/cm^(2) in a half-cell measurement,and a cell voltage of 1.675 V at 0.4 A/cm2for single-cell operation.A combined experimental and theoretical study(density functional theory calculations)revealed that the superior HER activity was attributed to the presence of partially reduced metallic Ni with various defects and residual Al,which facilitated water adsorption,dissociation,and finally hydrogen evolution.