Strategic pathway selection for photocatalytic degradation: roles of holes and radicals

Abstract

As global resources become scarce and environmental issues become increasingly severe, developing photocatalytic technology for efficiently and cleanly degrading pollutants has become a research trend. Radical degradation pathways are highly regarded owing to their wide application and efficiency in handling pollutants. Comparatively, direct oxidation by holes exhibits unique advantages in dealing with specific types of pollutants, and both degradation pathways have their own characteristics and strengths. However, past research on pollutant degradation has mainly focused on radical degradation, with little recognition of the role of direct hole oxidation in pollutant degradation, and there is a lack of attention toward the transition between the two pathways. This has made it difficult to select the most effective degradation strategy for different types of pollutants. To fill the knowledge gap in photocatalytic degradation pathways and overcome the predicament of blindly dealing with pollutants, the characteristics of these two oxidation pathways and their transition mechanisms are systematically explored. Additionally, this study provides the first summary of the types of pollutants that are suitable for degradation by holes and radicals. This paper offers a clear basis for selecting the most appropriate photocatalytic strategy according to the characteristics of different pollutants and reaction conditions, aiming to enhance researchers’ understanding of pollutant degradation and promote the development of environmental management technology towards higher efficiency and precision.