Understanding the intricate mechanisms from material fabrication to catalytic reaction is crucial in energy chemistry. Herein, we elucidate the underlying mechanisms from catalyst to catalysis on Ir-segregated SrIrO 3 (Ir/SrIrO 3 ) as an efficient hydrogen evolution reaction (HER) catalyst in acidic conditions. During the phosphorization-assisted reduction process, in-situ spectroscopic analysis revealed that hydrogen radicals (H·) from the dissociation of P-H bonds attack the lattice oxygen at edge Ir-O sites, resulting in the segregation of Ir atoms and the formation of robust Ir-O interfacial structures between exsolved Ir clusters and the oxygen sites in SrIrO 3 . These interfacial structures are essential for the high performance of HER, while SrIrO 3 provides structural stability. The protons in the electrolyte are activated at the Ir nanocluster sites, incorporating oxygen in SrIrO 3 through the Ir-O interface, forming a reconstructed Ir-OH structure. This structure maintains both thermodynamic and electrochemical stability by adjusting hydrogen diffusion, embedding, and surface hydrogen coverage to sustain dynamic equilibrium during the catalytic process. Theoretical analysis confirms the necessity of the stable Ir-O interface via Ir- 5d and O- 2p orbital hybridization and hydrogen intercalation, optimizing charge redistribution, hydrogen bond length, and hydrogen adsorption free energy for enhanced HER kinetics. This study provides new insights into catalyst development by elucidating the relationship between catalyst structure and catalytic performance.
The mechanistic role of interfacial electron transfer in enabling reversible hydrogen spillover for enhanced hydrogen evolution reaction (HER) kinetics remains fundamentally unexplored. Herein, we report a lattice-matched PtCoNiCuZn/ WC x N 1-x heterostructure electrode, where interfacial electron transfer triggers reversible hydrogen spillover, thereby achieving exceptional HER performance. Advanced characterization reveals coherent and semicoherent interfaces that induce charge redistribution, creating electron-deficient Pt sites with optimally downshifted d-band centers. The electrode exhibits a remarkable mass activity of 4.63 A mgPt −1 , which is 22 times higher than that of commercial Pt/C, and demonstrates exceptional stability for over 300 h at 10 mA cm −2 , attributed to strong metal-support interactions (SMSI). Density functional theory (DFT) calculations confirm a reversible hydrogen spillover mechanism driven by a built-in electric field at the heterojunction. This electric field facilitates *H migration from WCN to the alloy, alleviating hydrogen accumulation on the support and enhancing metal-site desorption, thus accelerating HER kinetics. This study provides critical insights into the role of interfacial electron transfer in hydrogen spillover and establishes a rational design strategy for highly active and stable self-supported electrodes in sustainable hydrogen production.
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