Photocatalyst degradation of perfluorooctanoic acid in water: Mechanisms, approaches, and perspectives

Perfluorooctanoic acid (PFOA) is a synthetic organic compound widely used in commercial and industrial products. Due to its high persistence, bioaccumulation, and toxicological properties, PFOA poses a serious risk to human health and the natural environment. Photocatalysis, as a clean energy technology for the potential removal of PFOA, has attracted considerable attention in recent years. However, the efficiency of the photodegradation of PFOA is limited mainly due to three reasons: (i) low light utilization, (ii) rapid electron-hole recombination, and (iii) low utilization of photogenerated carriers. Therefore, this review aims to provide a systematic summary based on current state-of-the-art approaches to designing and fabricating semiconductor photocatalysts to improve the rate of PFOA degradation. Specifically, the fundamental mechanism of photodegradation processes is first introduced, followed by a review of the improvement approaches for enhanced visible-light absorption of photocatalysts, inhibition of electron-hole recombination, and utilization of photogenerated carriers. In addition, this review discusses the principal effects of different semiconductor modifications on their performance in photodegradation systems. Finally, a summary and outlook on the challenges and future directions of semiconductor photocatalysis in practical water treatment are provided. This review contributes to understanding photodegradation mechanisms, promoting photocatalyst development, and opening a pathway for the sustainable treatment of PFOA in water.