Improving the electrocatalytic activity for hydrogen evolution reaction by lowering the electrochemical impedance of RuO2/Ni-P

In this paper Ni-P, RuO2 and RuO2/Ni-P composites were deposited on Ni plates through pulsed electrodeposition method, and their activities for HER in alkaline solution were studied comparatively. Scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS) analysis confirmed the formation of every composite. The electrochemical impedance spectroscopy (EIS) showed that Ni-P/Ni had lower charge transfer resistance at high overpotential and higher charge transfer resistance at low overpotential than RuO2/Ni. While Ni-P/Ni exhibited lower catalytic activity for HER at low overpotential and higher catalytic activity at high overpotential than RuO2/Ni. Meanwhile, RuO2/Ni-P/Ni had the lowest charge transfer resistance and highest catalytic activity among the three electrodes at both low and high overpotentials. It indicated that RuO2/Ni-P/Ni with less Ni-P and RuO2 exhibited enhanced catalytic activity for HER than both RuO2/Ni and Ni-P/Ni, due to an electron charge transfer synergistic effect of RuO2 and Ni-P.