Highly Efficient Photoelectrocatalytic Reduction of CO2 to Methanol by a p–n Heterojunction CeO2/CuO/Cu Catalyst

Photoelectrocatalytic reduction of COto fuels has great potential for reducing anthropogenic COemissions and also lessening our dependence on fossil fuel energy. Herein, we report the successful development of a novel photoelectrocatalytic catalyst for the selective reduction of COto methanol, comprising a copper catalyst modified with flower-like cerium oxide nanoparticles(CeONPs)(a n-type semiconductor) and copper oxide nanoparticles(CuO NPs)(a p-type semiconductor). At an applied potential of-1.0 V(vs SCE) under visible light irradiation, the CeONPs/CuO NPs/Cu catalyst yielded methanol at a rate of 3.44 μmol cmh, which was approximately five times higher than thatof a CuO NPs/Cu catalyst(0.67 μmol cm-2 h). The carrier concentration increased by ～ 108 times when the flower-like CeONPs were deposited on the CuO NPs/Cu catalyst, due to synergistic transfer of photoexcited electrons from the conduction band of CuO to that of CeO, which enhanced both photocatalytic and photoelectrocatalytic COreduction on the CeONPs. The facile migration of photoexcited electrons and holes across the p–n heterojunction that formed between the CeOand CuO components was thus critical to excellent light-induced COreduction properties of the CeONPs/CuO NPs/Cu catalyst. Results encourage the wider application of composite semiconductor electrodes in carbon dioxide reduction.