Countering microplastics pollution with photocatalysis: Challenge and prospects

The rapid increase in plastic production and disposal worldwide has adversely and significantly impacted the global environment and biology. Traditional treatment methods are not appropriate for microplastics (MPs) due to their highly polymerized, stable, and complex chemical structure. Photocatalytic degradation of MPs is a relatively new and environmentally friendly approach. This review summarizes the common sources and types of MPs, and covers the various strategies and methods for degrading MPs. It describes the recent developments in the photocatalytic degradation of MPs by transition metals catalysts as well as noble metal catalysts, and discusses the characteristics and limitations of each type of catalyst. It was found out that some photo-catalysts showed very good performance for degradation of MPs, but many of the literature failed to clarify the bond-breaking mechanism during photocatalytic reaction. This review tries to elucidate the bond-breaking mechanisms of various types of MP in photocatalytic process. Advice for future research directions is proposed by investigating the knowledge gaps between those reported literature. The main purpose of this review is to provide a comprehensive summarization for the current research status of photocatalytic degradation of MPs. This work may help researchers explore new photocatalytic methods for future MP control.