Modulating d-band centers in FeNiP@Cu2S nanoarrays by Co-Mn synergistic doping and heterojunction for efficient overall water splitting

This work addresses electrocatalytic limitations via d-band tuning through bimetallic co-doping and heterostructures. A CoMn-FeNiP@Cu 2 S nanorod heterostructured electrocatalyst was synthesized via hydrothermal and electrodeposition methods. Benefiting from the Cu 2 S substrate's excellent dispersibility, the catalyst possesses abundant active sites, superhydrophilicity, and rapid gas-desorption capability, facilitating reaction intermediate transport. In alkaline electrolyte, it exhibits outstanding bifunctional performance, requiring overpotentials of 196 mV (OER) and 176 mV (HER) at 100 mA cm −2 . For overall water splitting, a low cell voltage of 1.67 V delivers 100 mA cm −2 with stable operation over 100 h. DFT calculations reveal FeNiP@Cu 2 S promotes charge transfer and modulates Fe sites' d-band center via d-p hybridization, optimizing *OH adsorption. Co-Mn co-doping further tunes the electronic structure, shifting Ni sites' d-band center to the volcano plot optimal region and balancing HER hydrogen adsorption/desorption. This work develops high-performance electrocatalysts, elucidates d-band center modulation, and offers a new paradigm for advanced electrocatalyst design.