Synergism between {111} and {100} Crystal Facets on Cu₂O for Boosted Photothermal Catalysis

Cu₂O with different morphologies (Cu₂O-C (Cube), Cu₂O-CB (Cuboctahedra), and Cu₂O-O (Octahedra)) was synthesized to investigate the effect of crystal planes for the photothermal catalytic oxidation of toluene. It was found that the order of catalytic activity was as follows: Cu₂O-CB > Cu₂O-O > Cu₂O-C. The H₂-TPR and XPS results showed that the {111} facets were more susceptible to oxidation, and the oxidized structure was more difficult to reduce. The combination of {100} and {111} on Cu₂O-CB showed a synergistic effect between the oxidation and reduction cycle. Moreover, the {100} facets showed high electron-hole separation efficiency, which could promote the formation of •O₂^- species. In-situ DRIFTS results provided a comprehensive reaction pathway: toluene was oxidized to form benzyl alcohol or benzaldehyde and then subsequently oxidized to benzoic acid and ultimately converted to CO₂ and H₂O. All these results provided a fundamental understanding of the effect of the crystal plane on the photothermal catalysis reaction.