Modulating electronic structure with sulfur doping to enhance hydrogen coverage and accelerate hydrogen evolution reaction

Optimizing the surface electronic structure of catalysts is crucial for enhancing the kinetics of the hydrogen evolution reaction (HER). Herein, We have successfully fabricated sulfur (S)-doped nickel hydroxide loaded iridium-rhodium alloy heterojunction catalysts (RhIr/S-Ni(OH)₂/NF). The introduction of the highly electronegative element S into the Ni(OH)₂ lattice can modulate the electronic structure of the catalyst surface, thus keeping the RhIr alloy in an electron-rich state. In this state, water dissociation occurs on the S-Ni(OH)₂, while hydrogen adsorption and desorption take place on the RhIr active sites. Such modification significantly improves the hydrogen adsorption free energy while promoting efficient desorption kinetics, leading to superior catalytic activity of RhIr/S-Ni(OH)₂/NF. The prepared RhIr/S-Ni(OH)₂/NF catalyst possesses outstanding performance for HER, with overpotentials of just 9 mV and 125 mV at the current density of 10 and 100 mA cm⁻², respectively, and it sustains working at 500 mA cm⁻² for 400 hours. This research presents a novel electronic regulation strategy and provides valuable insights for the development of advanced electrocatalysts.