An Electrolyte Additive Strategy for Enhancing Water-Splitting Hydrogen Production of Nickel-Based Electrodes

Sustainable water electrolysis has emerged as a future technology for producing green hydrogen. The general approach to improving water-splitting hydrogen production is to develop novel electrode materials. In this work, we reported an orthogonal approach, namely, regulating the electrolyte components. As a proof of concept, Na₂S additive was introduced to the electrolytes to enhance the water-splitting performance of Ni-based electrodes. Specifically, a tiny amount of Na₂S (50 mM) was employed as an electrolyte additive to reduce the hydrogen evolution overpotential of the Ni(OH)₂ electrode from 262 to 193 mV at 10 mA cm^–2. In situ Raman studies unveiled the formation of the NiS active phase and the S–H bond during electrocatalysis, which were responsible for such a performance improvement. Moreover, such an electrolyte additive strategy also showed its success in other Ni-based materials such as metallic Ni foam, other electrolytes such as saline water, and other catalytic reaction systems such as oxygen evolution.