Construction of melamine foam–supported WO3/CsPbBr3 S–scheme heterojunction with rich oxygen vacancies for efficient and long–period CO2 photoreduction in liquid–phase H2O environment

Abstract

CO2 photoreduction of CsPbBr3 is still restricted due to its low conversion efficiency, poor water–resistance, and high toxicity of lead. In this study, three–dimensional porous melamine foam (MF) supported WO3/CsPbBr3 S–scheme heterojunctions with appropriate surface oxygen vacancies are constructed, successfully achieving efficient and long–period CO2 photoreduction in liquid–phase H2O environment. WO3 rods (R–WO3) and WO3 sheets (S–WO3) are fabricated by controlling the precursor solutions with rich and poor Cl−, respectively, which self–assembly incorporate with CsPbBr3 to form heterojunctions. A S–scheme charge transfer pathway is created in WO3/CsPbBr3, which facilitates charge separation and retains strong redox ability of composites simultaneously. S–WO3 possesses the higher specific surface area and oxygen vacancies concentration than R–WO3, contributing to photocatalytic activity. MF/S–WO3/CsPbBr3 exhibites the best CO2 conversion efficiency, with electron consumption rate of 1720.60 μmol/g/h, which ascribes to the synergy effect of MF support, S–scheme heterojunction and oxygen vacancies. Moreover, MF/S–WO3/CsPbBr3 realizes the long–period CO2 photoreduction, with no obvious decrease of products yield after eight 8–h cycles of tests. Furthermore, the strong adherence of sample on MF support could reduce the contamination of toxic Pb2+ leakage to environment.