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 TiO₂ 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 TiO₂ 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-TiO₂/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.

Keywords

hydrogen evolution reaction / near-zero-valent Pt state / oxygen vacancies / single-atom catalysts

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