Neumüller Daniela, Rafailović Lidija D, Pašti Igor A, Griesser Thomas, Gammer Christoph, Eckert Jürgen
Department of Materials Science, Montanuniversität Leoben, Leoben, 8700, Austria.
University of Belgrade - Faculty of Physical Chemistry, Belgrade, 11158, Serbia.
Small. 2024 Nov;20(45):e2402200. doi: 10.1002/smll.202402200. Epub 2024 Aug 7.
NiMo alloys are considered highly promising non-noble Hydrogen Evolution Reaction (HER) catalysts. Besides the synergistic effect of alloying elements, recent attention is drawn to the Mo leaching from the catalyst. This work investigates the role of Mo in NiMo alloys during HER, aiming to understand the interplay between compositional, structural, and electronic factors on the activity, and their effects on the electrode material and catalyst properties. For this purpose, sputter-deposited low roughness NiMo thin films are produced. The investigation of catalyst performance depending on their chemical composition shows a volcano-shaped plot, peaking for the NiMo alloy with the highest intrinsic activity in alkaline HER. A comprehensive electrode surface analysis combining transmission electron microscopy, X-ray photoelectron spectroscopy and atomic force microscopy identifies the leaching of Mo on a structural level and indicates the formation of a Ni(OH)-rich surface area. The ultimate surface characteristics of the NiMo catalysts depend on the initial composition and the electrochemical procedure. Based on the findings, it conclude that the observed catalytic properties of NiMo alloys in HER are determined by a complex interplay of increasing roughness, available surface species and their synergies. The leaching of Mo has a proven structural effect and is considered one of several factors contributing to the enhanced catalyst activity.
镍钼合金被认为是非常有前景的非贵金属析氢反应（HER）催化剂。除了合金元素的协同效应外，催化剂中钼的浸出最近也受到关注。这项工作研究了钼在HER过程中在镍钼合金中的作用，旨在了解成分、结构和电子因素对活性的相互作用，以及它们对电极材料和催化剂性能的影响。为此，制备了溅射沉积的低粗糙度镍钼薄膜。根据其化学成分对催化剂性能的研究显示出一个火山形曲线，在碱性HER中具有最高本征活性的镍钼合金达到峰值。结合透射电子显微镜、X射线光电子能谱和原子力显微镜的综合电极表面分析在结构层面上确定了钼的浸出，并表明形成了富含Ni(OH)的表面积。镍钼催化剂的最终表面特性取决于初始组成和电化学过程。基于这些发现，得出结论：在HER中观察到的镍钼合金的催化性能是由粗糙度增加、可用表面物种及其协同作用的复杂相互作用决定的。钼的浸出具有已证实的结构效应，被认为是导致催化剂活性增强的几个因素之一。
