Li Yibing, Tan Xin, Chen Sheng, Bo Xin, Ren Hangjuan, Smith Sean C, Zhao Chuan
School of Chemistry, The University of New South Wales, Sydney, NSW, 2052, Australia.
Materials Design Laboratory, Department of Applied Mathematics, Research School of Physics and Engineering, The Australian National University, Canberra, ACT, 2601, Australia.
Angew Chem Int Ed Engl. 2019 Jan 8;58(2):461-466. doi: 10.1002/anie.201808629. Epub 2018 Dec 7.
Nickel-heteroatoms bridge sites are important reaction descriptors for many catalytic and electrochemical processes. Herein we report the controllable surface modification of nickel-nitrogen (Ni-N) bridge sites on metallic Ni particles via a simplified vapor-assisted treatment approach. X-ray absorption spectroscopy (XAS) and Operando Raman spectroscopy verifies the interaction between Ni and surface-anchored N, which leads to distorted Ni lattice structure with improved wettability. The Ni-N bridge sites with appropriate N coverage level plays a critical role in the enhanced hydrogen evolution reaction (HER) and the optimized electrode (Ni-N ) has demonstrated superior HER performances with low overpotential merely of 42 mV for achieving a current density of 10 mA cm , as well as favorable reaction kinetics and excellent durability in alkaline electrolyte. DFT calculations revealed that the appropriate N-coverage level can lead to the most favorable ΔG kinetics for both adsorption of H* and release of H , while high N coverage (Ni-N ) results in weaker H* adsorption, thus a decreased HER activity, corresponding well to our experimental observations. Furthermore, this generic synthetic approach can also be applied to prepare S-modified Ni HER catalyst by generating hydrogen sulfide vapor.
镍-杂原子桥位是许多催化和电化学过程的重要反应描述符。在此，我们报道了通过一种简化的气相辅助处理方法对金属镍颗粒上的镍-氮（Ni-N）桥位进行可控的表面修饰。X射线吸收光谱（XAS）和原位拉曼光谱证实了镍与表面锚定氮之间的相互作用，这导致镍晶格结构扭曲，润湿性提高。具有适当氮覆盖水平的Ni-N桥位在增强析氢反应（HER）中起关键作用，优化后的电极（Ni-N）在碱性电解液中表现出优异的HER性能，实现10 mA cm电流密度时的过电位仅为42 mV，同时具有良好的反应动力学和出色的耐久性。密度泛函理论（DFT）计算表明，适当的氮覆盖水平可导致H吸附和H释放的最有利ΔG动力学，而高氮覆盖（Ni-N）导致H吸附较弱，从而降低HER活性，这与我们的实验观察结果非常吻合。此外，这种通用的合成方法还可用于通过生成硫化氢蒸气来制备S修饰的Ni HER催化剂。
