Photocatalytic Acetic Acid Production with High Selectivity from Conversion of CH₄ and CO Under Mild Conditions

Solar-driven direct carbonylation of CH₄ to value-added C₂ chemicals, such as acetic acid (CH₃COOH), offers a promising pathway toward carbon neutrality under mild conditions, but the performance is largely impeded by the ineffective activation of C─H bond and limited control over CH₃‒CO coupling. Here, we report that through rational surface decoration of Pd nanoparticles (NPs) and oxygen vacancy (V_O), selective photocatalytic CH₃COOH production is realized on WO₃ nanosheets from co-conversion of CH₄ and CO at room temperature and ambient pressure. Under light irradiation, the optimal Pd/V_O-WO₃ photocatalyst exhibits efficient CH₃COOH production with a yield rate of 52.7 µmol g^-1 h^-1 and a selectivity of 63.7% in the presence of H₂O₂ oxidant. Combined in situ spectroscopies and computational calculations reveal that V_O serves as the active site for CH₄ adsorption, while Pd NPs facilitates the activation of H₂O₂ into ·OH radicals to promote CH₄ dissociation to ^*CH₃ intermediate, thus leading to subsequent CH₃‒CO coupling for CH₃COOH production over Pd/V_O-WO₃. This work paves a new path into photocatalytic CH₄ carbonylation to targeted C₂₊ products under mild conditions via synergistic active sites.