Construction of defect-engineered three-dimensionally ordered macroporous WO3 for efficient photocatalytic water oxidation reaction

To improve solar light harvesting and charge separation efficiency, we develop a facile strategy for synthesizing defect-engineered three-dimensionally ordered macroporous (3DOM) WO3 photonic crystals via the colloidal crystal template method and subsequent H2/N2 atmosphere thermal treatment. The oxygen evolution rate of the obtained defect-engineered 3DOM WO3 (W270–400) is 40.1 μmol h−1, which is much higher than that of the untreated 3DOM WO3 and the defect-engineered WO3 nanoparticles. The enhanced performance is due to the good light harvesting and excellent charge transportion properties. The results show that the slow photon effect and bulk oxygen vacancy (VO) induced narrowed band gap greatly improve the light harvesting efficiency, while abundant surface VO can lower the valence band to increase the driving force for water oxidation, and thus significantly promote electron–hole separation. Our work can guide further design and preparation of high-efficiency defect-engineered 3DOM semiconductors for solar energy conversion.