Oxygen-vacancy-assisted construction of FeOOH/CdS heterostructure as an efficient bifunctional photocatalyst for CO2 conversion and water oxidation

An efficient bifunctional photocatalyst for CO2 reduction and water oxidation based on a heterostructure with FeOOH nanospindles (NSs) and CdS nanocrystals (NCs) is reported. The microstructure characterizations and theoretical calculations reveal that surface oxygen vacancies (VO) at FeOOH NSs provide preferential deposition sites not only for CdS NCs to grow high-quality interface and form the heterostructure, but also for inert molecule adsorption. Owing to the synergistic effects of the VO-assisted interfacial charge transfer and surface reactions, the optimized FeOOH/CdS heterostructures display a single-carbon compound production rate of 18.43 μmol g−1 h−1 (5.88 μmol g−1 h−1 for CH4, 12.55 μmol g−1 h−1 for CO), about 6.2 and 8.5 times higher than their separated counterparts, and an O2 evolution rate of 676.50 μmol g−1 h−1 under visible-light irradiation. This work demonstrates for the first time the essential role of surface VO in the FeOOH/CdS heterostructures and their synergistic effects on photocatalysis performance.