Synergistic effect of Z-scheme and oxygen vacancy of CeO2/WO3 heterojunction for enhanced CO2 reduction activity

[Display omitted] •The synergistic effect of oxygen vacancies and Z-scheme promoted the activity of CO2 reduction.•The heterojunction formation inhibited the charge recombination.•Multielectron CO2 conversion was attained by Z-scheme CeO2/WO3 photocatalyst. Photocatalytic CO2 reduction shows great prospects in producing clean energy and solving environmental pollution. However, the activity of traditional photocatalysts is confined by poor carrier separation. In this paper, cerium oxide (CeO2) and tungsten oxide (WO3) were combined by an electrostatic self-assembly method to form a CeO2/WO3 Z-scheme heterojunction for photocatalytic CO2 reduction. With the active combination, it is discovered that Z-scheme provided an interfacial free charge carrier and the availability of oxygen vacancies offered active sites, which ultimately increased the CO2 photoconversion activity 30.1 µmol·g−1·h−1 into CO by the CeO2/WO3 composite, much higher than that of pristine CeO2. Furthermore, the enhanced light absorption and a low defective surface contributed to the enriched interfacial conversion efficiency upon heterojunction formation. The urbach energy tail (Eu) of the composite offered the slow charge recombination rate that enhanced CO2 reduction. This paper offered an idea for constructing synergistic interfacial interaction in Z-scheme heterostructure for enhancing the activity of CO2 reduction.