Neumüller Daniela, Rafailović Lidija D, Jovanović Aleksandar Z, Skorodumova Natalia V, Pašti Igor A, Lassnig Alice, Griesser Thomas, Gammer Christoph, Eckert Jürgen
Department of Materials Science, Montanuniversität Leoben, 8700 Leoben, Austria.
University of Belgrade-Faculty of Physical Chemistry, 11158 Belgrade, Serbia.
Nanomaterials (Basel). 2023 Jul 17;13(14):2085. doi: 10.3390/nano13142085.
Highly effective yet affordable non-noble metal catalysts are a key component for advances in hydrogen generation via electrolysis. The synthesis of catalytic heterostructures containing established Ni in combination with surface NiO, Ni(OH), and NiOOH domains gives rise to a synergistic effect between the surface components and is highly beneficial for water splitting and the hydrogen evolution reaction (HER). Herein, the intrinsic catalytic activity of pure Ni and the effect of partial electrochemical oxidation of ultra-smooth magnetron sputter-deposited Ni surfaces are analyzed by combining electrochemical measurements with transmission electron microscopy, selected area electron diffraction, X-ray photoelectron spectroscopy, and atomic force microscopy. The experimental investigations are supplemented by Density Functional Theory and Kinetic Monte Carlo simulations. Kinetic parameters for the HER are evaluated while surface roughening is carefully monitored during different Ni film treatment and operation stages. Surface oxidation results in the dominant formation of Ni(OH), practically negligible surface roughening, and 3-5 times increased HER exchange current densities. Higher levels of surface roughening are observed during prolonged cycling to deep negative potentials, while surface oxidation slows down the HER activity losses compared to as-deposited films. Thus, surface oxidation increases the intrinsic HER activity of nickel and is also a viable strategy to improve catalyst durability.
高效且经济实惠的非贵金属催化剂是通过电解制氢取得进展的关键组成部分。合成包含已确定的镍并结合表面氧化镍、氢氧化镍和羟基氧化镍域的催化异质结构，会在表面组分之间产生协同效应，这对水分解和析氢反应（HER）非常有利。在此，通过将电化学测量与透射电子显微镜、选区电子衍射、X射线光电子能谱和原子力显微镜相结合，分析了纯镍的本征催化活性以及超光滑磁控溅射沉积镍表面的部分电化学氧化效应。实验研究辅以密度泛函理论和动力学蒙特卡罗模拟。在不同的镍膜处理和操作阶段仔细监测表面粗糙度的同时，评估析氢反应的动力学参数。表面氧化导致主要形成氢氧化镍，表面粗糙度几乎可以忽略不计，析氢反应交换电流密度增加3至5倍。在长时间循环至深负电位期间观察到更高水平的表面粗糙度，而与沉积态薄膜相比，表面氧化减缓了析氢反应活性损失。因此，表面氧化提高了镍的本征析氢反应活性，也是提高催化剂耐久性的可行策略。
