Multi-Band Centre Co-Tailoring of Iridium Diphosphide Nanoclusters Motivating Industrial Current Density Hydrogen Production

Transition metal phosphides (TMPs) are high-potential catalysts for hydrogen evolution reaction (HER) yet struggle with the long-term maintenance of high activity at ampere-level current densities. Size cutting and heteroatom modification of TMPs are effective ways to improve their surface affinities and catalytic efficiencies, but the particle stabilities and synergistic regulation of band structures at different sites have become huge challenges. Herein, we have successfully synthesized cluster-level sulfur-doped iridium diphosphide (S-IrP₂) through a molecular engineering strategy. It requires only low overpotentials of 133.6 ± 1.2 and 217.2 ± 2.6 mV to drive industrial current densities of 1.0 and 2.0 A·cm^–2, respectively, being one of the best alkaline HER catalyst. Moreover, it showed almost no activity loss over 20,000 cycles and exhibited a remarkable charge transfer amount that exceeds those of reported TMPs. The electronic tailoring of IrP₂ by sulfur atoms enables simultaneous shifting of the d-band and f-band centers of Ir and the p-band center of P, which co-optimizes the H and OH adsorption to lowering the H migration and H₂ formation barriers. This work demonstrates that the molecular confinement synthesis holds tremendous prospects for architecting ultrafine metallic compounds with re-definable active surfaces.