Coupling photocatalytic CO2 reduction with benzyl alcohol oxidation to produce benzyl acetate over Cu2O/Cu

Photocatalytic reduction of CO2 to produce valuable chemicals can simultaneously reduce the greenhouse effect and relieve the energy shortage pressure. However, CO2 reduction over semiconductor-based photocatalysts usually generates C1 products. In this manuscript, we reported the preparation of a Cu2O/Cu nanocomposite for photocatalytic CO2 reduction under visible light. Since Cu2O has a narrow band gap, photocatalytic CO2 reduction over the as-obtained Cu2O/Cu was carried out in the presence of benzyl alcohol as the sacrificial agent to inhibit the possible oxidation of Cu+ by the photo-generated holes and to complete the photocatalytic cycle over Cu2O. It was found that benzyl acetate, instead of C1 products, was generated as the main product over Cu2O/Cu, which can be ascribed to a successful coupling of CO2 reduction and benzyl alcohol oxidation promoted by metallic Cu. After reaction, metallic Cu in Cu2O/Cu was oxidized to CuO, which led to the deactivation of the catalyst. However, the catalyst can be regenerated by reduction to recover its performance for producing benzyl acetate. The strategy by coupling photocatalytic CO2 reduction with the oxidation of organics not only can lead to valuable multi-carbon organics from CO2 reduction, but also can be used to inhibit the photo-corrosion of narrow-band gap semiconductor-based photocatalysts during photocatalytic reactions.