Cu²⁺-Decorated Porous Co₃O₄ Nanosheets for Photothermocatalytic Oxidation of Toluene

Surface decoration has been demonstrated as one of effective ways of improving the catalytic activities of nanostructured materials. Herein, we report quenching as an effective synthetic strategy for decorating porous Co3O4 nanosheets. The hot Co3O4 nanosheets are poured into an aqueous solution of copper nitrate to obtain a surface Cu-decorated Co3O4 catalyst (Cu-Co3O4-Q). Cu-Co3O4-Q exhibits significant photothermocatalytic activity for toluene oxidation under irradiation of the full solar spectrum with light of 834 mW cm–2 (space velocity of 72000 mL g–1 h–1). The reaction rate of Cu-Co3O4-Q is 1.76 times higher than that of Co3O4. Comprehensive characterizations demonstrate that the Cu decoration is confined to the limited surface layers of Co3O4, different from a traditional hydrothermal synthesis method (Cu-Co3O4-T). Cu2+ substitution for Co2+ is preferred over Co3+ on the surface of Cu-Co3O4-Q and thus produces more active sites, leading to a catalytic activity comparable to that of partially supported noble-metal catalysts. The present work demonstrates that quenching is a facile and useful strategy for the decoration of nanostructured materials with enhanced photothermocatalytic performance.