Engineering tandem double p-n heterostructured CeO2@CdS-Cu8S5 hollow spheres for remarkable photocatalytic CO2 reduction

Carbon cycling and value-added CO2 utilization through photocatalytic CO2 reduction are effective strategies for solving environmental problems and energy crises. Here, we rationally design and fabricate a double p-n heterostructured CeO2@CdS-Cu8S5 double-shelled hollow sphere (DSHSs) photocatalyst, which efficiently and stably performs photocatalytic CO2 reduction under visible light irradiation. Firstly, CeO2 hollow spheres were prepared by the template-assisted method. Then ultrathin CdS nanolayers were grown in situ by the chemical bath deposition method. Finally, part of the CdS was converted to Cu8S5 by cation exchange, resulting in the CeO2@CdS-Cu8S5 hybrid with uniform interfacial contact and ultrathin double-shelled hollow spherical structure. The constructed tandem double p-n heterostructure contributes to the excellent photo-induced charge separation and migration capability of the CeO2@CdS-Cu8S5 photocatalyst. Thanks to the multiple light scattering inside the double-shelled hollow structure, solar radiation can be absorbed more efficiently. In addition, the abundant exposed active sites also significantly contribute to the chemisorption of CO2 molecules and the progress of surface redox reactions. Based on the above properties, the optimized CeO2@CdS-Cu8S5 DSHSs without any noble metal cocatalyst exhibited excellent activity (18.25 µmol g–1h−1) and high selectivity (89.3%) during the photocatalytic reduction of CO2 deoxygenation to CH4.