Photocatalysis technology, using semiconductor nano-materials to decompose toxic pollutants under solar light irradiation, displays great prospects for environmental protection. This review gives an overview of the applications of BiOX (X = Cl, Br and I) photocatalysts for efficient photocatalytic degradation (PCD) removal of pollutants in water/air, such as volatile organic compounds (VOCs), organic molecule pollutants, polymer pollutants and biological substances. In addition, the hybridization, facet effects and photocatalytic mechanisms of BiOX are highlighted to offer guidelines for designing highly-active BiOX visible-light-driven (VLD) photocatalysts. Furthermore, the research trends and future prospects of BiOX photocatalysts are also briefly summarized. It may lead to feasible green and efficient photocatalytic reaction systems using BiOX as the photocatalyst.

Photocatalytic water splitting and carbon dioxide photoreduction are considered effective strategies for alleviating the energy crisis and environmental pollution. Polynuclear metal-oxo clusters possess excellent electron storage/release ability and unique catalytic properties via intermetallic synergy, which enables them with great potential in environmentally friendly photosynthesis. Importantly, metal-oxo clusters with precise structure can not only act as high-efficiency catalysts but also provide well-defined structural models for exploring structure–activity relationships. In this review, we systematically summarize recent progress in the catalytic application of polynuclear metal-oxo clusters, including polyoxometalate clusters, low-cost transition metal clusters, and metal-oxo-cluster-based metal–organic frameworks for water splitting and CO₂reduction. Furthermore, we discuss the challenges and solutions to the problems of polynuclear metal-oxo clusters in photocatalysis.

The shape-dependent photocatalytic activity of Bi₅O₇I is caused by facets synergetic and internal electric field effects.

BiOI@(BiO) ₂ CO ₃ facet coupling heterostructures were synthesized, and showed much higher photocatalytic activity than BiOI and (BiO) ₂ CO ₃ under visible light.