Highly Efficient Photoelectrocatalytic Reduction of CO(2) to Methanol by a p–n Heterojunction CeO(2)/CuO/Cu Catalyst

Photoelectrocatalytic reduction of CO(2) to fuels has great potential for reducing anthropogenic CO(2) emissions 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 CO(2) to methanol, comprising a copper catalyst modified with flower-like cerium oxide nanoparticles (CeO(2) NPs) (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 CeO(2) NPs/CuO NPs/Cu catalyst yielded methanol at a rate of 3.44 μmol cm(−2) h(−1), which was approximately five times higher than that of a CuO NPs/Cu catalyst (0.67 μmol cm(−2) h(−1)). The carrier concentration increased by ~ 10(8) times when the flower-like CeO(2) NPs 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(2), which enhanced both photocatalytic and photoelectrocatalytic CO(2) reduction on the CeO(2) NPs. The facile migration of photoexcited electrons and holes across the p–n heterojunction that formed between the CeO(2) and CuO components was thus critical to excellent light-induced CO(2) reduction properties of the CeO(2) NPs/CuO NPs/Cu catalyst. Results encourage the wider application of composite semiconductor electrodes in carbon dioxide reduction. [Image: see text] ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1007/s40820-019-0354-1) contains supplementary material, which is available to authorized users.