Pt–Ti Coordination at Oxygen Vacancies Activates Single‐Atom Catalysis for Broad‐pH Hydrogen Evolution

ABSTRACT Defect engineering serves as a cornerstone in the design of high‐efficiency single‐atom catalysts (SACs) for advanced electrocatalytic systems. This study demonstrates oxygen vacancy‐induced near‐zero‐valent Pt SACs anchored on TiO ₂ for efficient hydrogen evolution reaction (HER). Synchrotron spectroscopy and density functional theory calculation reveal that oxygen vacancies create unconventional Pt–Ti coordination while strengthening electronic metal‐support interactions. This facilitates substantial electron transfer from TiO ₂ to Pt, generating a near‐zero‐valent Pt state with elevated electron density. The modified electronic structure lowers the Pt d‐band center, reducing hydrogen intermediate (*H) adsorption energy and optimizing HER kinetics. Moreover, ab initio molecular dynamics and in situ Raman spectra show that the negative charge accumulated at the Pt site promotes K ⁺ enrichment at the interface, which enhances H–OH bond polarization and accelerates water dissociation kinetics. The resulting D‐TiO ₂ /Pt SACs exhibit superior HER activity across acidic, neutral, and alkaline conditions, achieving low overpotentials of 40, 57, and 60 mV at 10 mA cm ⁻² , respectively. Additionally, its mass activities at the overpotential of 100 mV are 10.3, 33.9, and 20.9 times higher that of Pt/C, respectively. This study shows the key role of defect‐mediated electronic engineering in tailoring SACs' valence states and catalytic functions, advancing sustainable hydrogen production through rational catalyst design.