Synergistic regulation of hydrogen adsorption/ desorption via dual interfaces of Cu/Ni/Ni(OH)2 toward efficient evolution reaction

Nickel-based catalysts have attracted tremendous attention as alternatives to precious metal-based catalysts for electrocatalytic hydrogen evolution reaction (HER) in virtue of their conspicuous advantages such as abundant reserves and high electrochemical activity. Nevertheless, a great challenge for Ni-based electrocatalyst is that nickel sites possess too strong adsorption for key intermediates H*, which severely suppresses the hydrogenproduction activities. Herein, we report a hierarchical architecture Cu/Ni/Ni(OH)2 consisting of dual interfaces as a high-efficient electrocatalyst for HER. The Cu nanowire backbone could provide geometric spaces for loading plenty of Ni sites and the formed Ni/Cu interface could effectively weakened the adsorption intensity of H* intermediates on the catalyst surface. Moreover, the H* adsorption could be further controlled to appropriate states by in-situ formed Ni(OH)2/Ni interface, which simultaneously promotes water adsorption and activation, thus both Heyrovsky and Volmer steps in HER could be obviously accelerated. Experimental and theoretical results confirm that this interface structure can promote water dissociation and optimize H* adsorption. Consequently, the Cu/Ni/ Ni(OH)2 electrocatalyst exhibits a low overpotential of 20 mV at 10 mA cm-2 and an ultralow Tafel slope of 30 mV dec �1 in 1.0 M KOH, surpassing those of reported transitionmetal-based electrocatalysts and even the prevailing commercial Pt/C. (c) 2022 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

Automated summary

This study reports a hierarchical architecture Cu/Ni/Ni(OH)2 electrocatalyst with dual interfaces as an efficient catalyst for the hydrogen evolution reaction. The catalyst provides geometric spaces for loading nickel sites and weakens the adsorption of H* intermediates. The in-situ formed Ni(OH)2/Ni interface further controls H* adsorption and promotes water adsorption and activation, accelerating the key steps in the hydrogen evolution reaction. The Cu/Ni/Ni(OH)2 electrocatalyst exhibits superior performance compared to other transition metal catalysts and commercial Pt/C catalysts.