CoNiP(S)@WC as a Bifunctional Electrocatalyst for Efficient Alkaline Water Splitting

Abstract

Developing low-cost and high-performance electrocatalysts for overall water splitting is essential for advancing sustainable hydrogen (H₂) production and renewable energy technologies. In this work, a bifunctional CoNiP(S)@WC electrocatalyst was successfully synthesized through a facile multi-step strategy involving hydrothermal treatment, followed by phosphorization and sulfurization. The integration of a Co-Ni phosphosulfide heterostructure with waste-wood-derived carbon provides abundant active sites, enhanced electrical conductivity, and improved structural stability, resulting in efficient catalytic activity toward both the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in alkaline media. The optimized catalyst exhibits low overpotentials of 38 mV for HER and 185 mV for OER at 10 mA cm^–2, along with favorable Tafel slopes, indicating fast reaction kinetics. Moreover, the synergistic electronic interactions among Co, Ni, P, and S species further enhance the intrinsic electrocatalytic performance. In a two-electrode alkaline electrolyzer, CoNiP(S)@WC achieves a low cell voltage of 1.45 V at 10 mA cm^–2 and demonstrates excellent long-term stability over 120 h of continuous operation. The results highlight the effectiveness of combining transition metal phosphosulfides with biomass-derived conductive carbon for the development of efficient, durable, and scalable electrocatalysts for practical alkaline water splitting and sustainable H₂ production.