Synergy of Pd atoms and oxygen vacancies on In₂O₃ for methane conversion under visible light

Methane (CH₄) oxidation to high value chemicals under mild conditions through photocatalysis is a sustainable and appealing pathway, nevertheless confronting the critical issues regarding both conversion and selectivity. Herein, under visible irradiation (420 nm), the synergy of palladium (Pd) atom cocatalyst and oxygen vacancies (OVs) on In₂O₃ nanorods enables superior photocatalytic CH₄ activation by O₂. The optimized catalyst reaches ca. 100 μmol h^-1 of C1 oxygenates, with a selectivity of primary products (CH₃OH and CH₃OOH) up to 82.5%. Mechanism investigation elucidates that such superior photocatalysis is induced by the dedicated function of Pd single atoms and oxygen vacancies on boosting hole and electron transfer, respectively. O₂ is proven to be the only oxygen source for CH₃OH production, while H₂O acts as the promoter for efficient CH₄ activation through ·OH production and facilitates product desorption as indicated by DFT modeling. This work thus provides new understandings on simultaneous regulation of both activity and selectivity by the synergy of single atom cocatalysts and oxygen vacancies.