Recent advances in synthesis, performance, and application of oxygen vacancy-enriched WO3−x photocatalysts

Defective tungsten oxides (WO 3− x ) with oxygen vacancies (OVs) are recognized for exceptional photocatalytic properties attributed to their unique electronic structures, abundant OVs, and local surface plasmon resonance effect. There has been a growing research interest in developing OV-rich WO 3− x as efficient photocatalysts for applications in environmental remediation and energy conversion. This review covers various available approaches for synthesizing WO 3− x , including hydrothermal, solvothermal, microwave, and template methods. It also focuses on recent progresses on several modification strategies, such as ion doping, metal deposition, morphology control, heterojunction construction, and single-atom engineering, for maximizing the photocatalytic efficiency of WO 3− x . The correlation between photocatalytic activity, chemical compositions, morphological characteristics, and textural properties of catalysts is highlighted. The application of these WO 3− x photocatalysts with improved performances in the fields of wastewater treatment, H 2 evolution, CO 2 reduction, N 2 fixation, photoelectrochemical catalysis, and stability is discussed. Finally, prospects and challenges in the synthesis and application of WO 3− x -based photocatalysts are outlined. Graphic abstract