Confinement of Indium Single Atoms in Cobalt Vacancies for Enhanced Photocatalytic CO₂-to-Methanol Conversion

Abstract

Photocatalytic conversion of carbon dioxide (CO₂) to methanol is hindered by inefficient charge separation and complex multielectron pathways. To address these challenges, we report a synergistic catalyst design in which cobalt vacancies (V_Co) are coupled with indium single atoms (In SAs). V_Co sites were precisely constructed on Co₃O₄ nanosheets using a chlorine cold plasma technique, acting as “atomic sockets” that confine In SAs and form a robust In–O–V_Co coordination structure. The resulting In/Co_3−xO₄ catalyst delivered a high methanol production rate of 466.7 μmol/(g·h) with 92.3% selectivity under simulated solar irradiation, which was eight times greater than that of the vacancy-free catalyst. Mechanistic studies revealed a synergistic functional division: the V_Co sites efficiently adsorbed and dissociated H₂O to supply protons, whereas the In SAs polarized CO₂ and stabilized the critical *COOH intermediate. This synergy of strong electronic metal–support interactions improved charge separation and steered the reaction pathway toward methanol, offering a novel atomic-level strategy for designing highly selective CO₂ photoreduction catalysts.

Graphical Abstract

Keywords

In/Co_3−xO₄ / Cobalt vacancies / Indium single atoms / Synergistic effect / CO₂ photoreduction / Methanol selectivity

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The Author(s) under exclusive licence to Tianjin University