Emerging layered BiO2-x for photocatalysis: status, challenges, and outlook

It is highly desired to develop new kinds of semiconductor photocatalysts for environmental remediation and energy production. Recently, BiO2-x, a new bismuth-based oxide has attracted considerable interest due to its narrow band gap, high number of defect sites, and its unique layered structure, which will play a significant role in photocatalysis in the future. By synthesizing BiO2-x-based nanocomposites with a thin layer structure, doped with various elements, or coupled with other semiconductors, it was demonstrated that they showed good photoactivity for H-2 production, organic pollutant degradation, O-2 activation, and so on. In this perspective, recently published works about bare BiO2-x, doped BiO2-x, and BiO2-x-based heterogeneous nanocomposites were summarized, including discussion about current issues, such as preparation method, non-defined structure, and poor charge separation. Finally, potential applications of BiO2-x photocatalysts were proposed in renewable energy production and environmental remediation.