He Wei, Feng Weihang, Sun ZhengMing
School of Materials Science and Engineering, Southeast University, Nanjing 211189, P.R. China.
Nanoscale. 2024 Oct 10;16(39):18518-18523. doi: 10.1039/d4nr02879a.
The sluggish dissociation of water in alkaline electrolytes significantly hinders the kinetics of the hydrogen evolution reaction (HER), particularly on surfaces of Ru-based catalysts. The structure of water at the water-catalyst interface influences this dissociation process, yet controlling the configuration of water molecules is challenging due to their random distribution. In this study, a NiRu alloy supported on nitrogen-doped carbon (NiRu/NC) is selected as a model catalyst to investigate the electron distribution of the catalyst manipulating the adsorption configuration and orientation of water molecules. The introduction of Ni leads to charge transfer from Ni to Ru atoms within the NiRu alloy, causing a notable redistribution of charge that strengthens the local electric fields surrounding the NiRu alloy. These electron-rich Ru sites attract K cations to the surface, resulting in an increased presence of K cation-hydrated water molecules, which is an H-down configuration with a reduced Ru-H distance. This phenomenon is confirmed by Raman spectroscopy. Consequently, NiRu/NC exhibits outstanding HER performance, achieving low overpotentials of 16 and 344 mV at current densities of 10 and 1000 mA cm, respectively.
碱性电解质中水分子的缓慢解离显著阻碍了析氢反应（HER）的动力学，尤其是在钌基催化剂表面。水-催化剂界面处水的结构会影响这种解离过程，然而由于水分子的随机分布，控制水分子的构型具有挑战性。在本研究中，选择氮掺杂碳负载的镍钌合金（NiRu/NC）作为模型催化剂，以研究催化剂的电子分布对水分子吸附构型和取向的影响。镍的引入导致镍钌合金内部的电荷从镍转移到钌原子，引起显著的电荷重新分布，增强了镍钌合金周围的局部电场。这些富电子的钌位点将钾阳离子吸引到表面，导致钾阳离子水合水分子的存在增加，这是一种H向下构型，且钌-氢距离减小。拉曼光谱证实了这一现象。因此，NiRu/NC表现出出色的析氢反应性能，在电流密度为10和1000 mA cm时，过电位分别低至16和344 mV。
