Review of Bi-based catalysts in piezocatalytic, photocatalytic and piezo-photocatalytic degradation of organic pollutants.

Photocatalysis, as an effective advanced oxidation process, has been widely carried out in water waste treatment, especially in the degradation of organic pollutants. However, the photocatalytic process is limited by the high recombination rate of photo-generated carriers. To improve photocatalytic efficiency, piezocatalysis has attracted increasing attention, especially that using lead-free piezoelectric materials, which avoids the secondary pollution of lead toxicity in the environment. Bi-based materials have both photocatalytic activity and piezocatalytic activity, which can perfectly combine the advantages of these two catalytic processes to promote the degradation of organic pollutants. Under an external mechanical action, the Bi-based catalyst produces a polarized electric field due to the piezoelectric effect, and the photo-generated carriers can be effectively separated under electrostatic attraction, thus obtaining more efficient photocatalytic performance. However, there are still many gaps in the design, reaction mechanism, and development prospects of Bi-based piezo-photocatalysts. Therefore, to acquire a deeper understanding of the research status of Bi-based piezo-photocatalysts, we summarize the existing literature to provide effective ways to improve piezo-photocatalytic performance. Moreover, this paper points out the developmental direction of piezo-photocatalysis in the future. Last but not least, we also look forward to the prospect of piezo-photocatalysis in the degradation of organic pollutants.