Systemically Understanding Aqueous Photocatalytic Upgrading of Microplastic to Fuels

Microplastics (MPs) are regarded as a pervasive contaminant that poses threats to the environment and human safety. However, the high energy storage potential of the C-C and C-H bonds in MPs has led to increased attention toward technological methods for upgrading plastic waste to high-value-added fuels. Aqueous photocatalysis has emerged as a promising approach for upgrading MPs due to its solar-driven properties and ability to generate various radicals. While extensive investigations and reviews have been conducted on photocatalysts and the resulting products within this system, there is an emerging need to comprehensively understand the entire process to enhance efficiency and selectivity further. In this review, significant advancements in the overall system are summarized, including reactants, pretreatments, photocatalysts, additives, and reactors, to enable efficient and selective reactions based upon the principles of state-of-the-art photocatalytic microplastic upgrading. Furthermore, the shortcomings are clarified with proposed possible breakthrough points in each research direction. Ultimately, the significance of developments in pretreatments is highlighted, paving the way for future research possibilities.