Metal-free photocatalysts for solar-driven water disinfection: recent progress and challenges

Today, providing a safe and reliable source of drinking water for people around the world is a huge sustainability challenge. Compared with the traditional water disinfection processes, photocatalytic disinfection as a new type of technology has been widely recognized and rapidly developed in recent decades. Among them, metal-free photocatalysts are popular because of their unique physicochemical properties and no risk of metal ion leaching. Here, we provide a comprehensive overview of the latest advances in solar-driven metal-free catalysts in the field of water disinfection. The development of metal-free photocatalysts represented by g-C3N4 is introduced in detail, including preparation methods, modification strategies and disinfection performances. From the perspectives of bacteria and viruses, the key photocatalytic disinfection mechanisms are elaborated and the role of active species is briefly introduced. In particular, the research progress of the photocatalytic reactors in microbial inactivation is highlighted in order to accelerate the large-scale application of photocatalysis in practical industry. Finally, some emerging challenges and problems are summarized, hoping to provide valuable guidance for the future development of this field. In this review, we overview the development of metal-free photocatalysts for water disinfection, the photocatalytic disinfection mechanisms and devices.