Charge-induced high-valence zirconium-doped CuCo2S4/Co(OH)2 nanowires promote bifunctional water splitting

Spinel-type materials are attracting great attention as potential electrocatalysts for the hydrogen- and oxygen-evolution reactions. However, their inherent catalytic activities are not on par with those of precious-metal catalysts, and their poor stabilities continue to constrain their rapid development. In this study, we fabricated Zr-CuCo 2 S 4 nanowires and Co(OH) 2 nanosheet–nanowires using electrochemical methods, resulting in lattice defects, sulfur vacancies, and more exposed active sites that catalyze the hydrogen- and oxygen-evolution reactions. DFT calculations revealed that sulfur vacancies enhance intrinsic activity, while Zr doping reduces the energy barrier for H*–OH* adsorption, promotes the formation of additional sulfur vacancies, and modulates active-site Cu/Co valence states, which greatly enhances water-dissociation and H*-adsorption kinetics. Consequently, Zr-CuCo 2 S 4 /Co(OH) 2 requires low overpotentials of 88 and 208 mV, respectively, to support highly stable alkaline hydrogen- and oxygen-evolution reactions at 10 mA cm −2 . This study provides a rational strategy for designing low-cost spinels for green and clean energy.