Multi-Band Centre\nCo-Tailoring of Iridium Diphosphide\nNanoclusters Motivating Industrial Current Density Hydrogen Production

Transition metal phosphides (TMPs) are high-potential\ncatalysts\nfor hydrogen evolution reaction (HER) yet struggle with the long-term\nmaintenance of high activity at ampere-level current densities. Size\ncutting and heteroatom modification of TMPs are effective ways to\nimprove their surface affinities and catalytic efficiencies, but the\nparticle stabilities and synergistic regulation of band structures\nat different sites have become huge challenges. Herein, we have successfully\nsynthesized cluster-level sulfur-doped iridium diphosphide (S-IrP<sub>2</sub>) through a molecular engineering strategy. It requires only\nlow overpotentials of 133.6 ± 1.2 and 217.2 ± 2.6 mV to\ndrive industrial current densities of 1.0 and 2.0 A·cm<sup>–2</sup>, respectively, being one of the best alkaline HER catalyst. Moreover,\nit showed almost no activity loss over 20,000 cycles and exhibited\na remarkable charge transfer amount that exceeds those of reported\nTMPs. The electronic tailoring of IrP<sub>2</sub> by sulfur atoms\nenables simultaneous shifting of the d-band and f-band centers of\nIr and the p-band center of P, which co-optimizes the H and OH adsorption\nto lowering the H migration and H<sub>2</sub> formation barriers.\nThis work demonstrates that the molecular confinement synthesis holds\ntremendous prospects for architecting ultrafine metallic compounds\nwith re-definable active surfaces.