Wood-derived cobalt nickel phosphide electrocatalyst as self-supporting electrodes for efficient overall water splitting

Abstract

Biomass-based transition metal carbon catalysts have gained significant attention in water splitting due to their ability to enhance the electrocatalytic activity and chemical stability of the hydrogen evolution reaction (HER). However, designing and optimizing these catalysts as self-supporting electrodes remains a significant challenge. Herein, we developed a wood-derived cobalt‑nickel phosphide electrocatalyst as a self-supporting electrode by pretreating wood chips with gluconic acid-based proton ionic liquids (GILs), followed by carbonization, electrodeposition, and phosphating. The self-supporting electrodes with a stable three-dimensional nanosheet structure exhibited superior HER performance, achieving a low overpotential of 107.62 mV at 10 mA cm⁻² and small Tafel slope of 79.52 mV dec⁻¹ in alkaline solution. Furthermore, the assembled two-electrode electrolyzer exhibited a water splitting voltage of only 1.66 V at the current density of 10 mA cm⁻². More importantly, the synergistic effect of phosphating bimetals significantly boosted electrocatalytic activity, leading to remarkable water splitting performance. This work introduces a novel approach for developing GILs, as well as providing a potential avenue for wood in the direction of self-supporting catalytic electrode.