Hybrid metal-free floatable photocatalysts for catalytic degradation of organic contaminants and inactivation of pathogens in water

Wastewater treatment has garnered significant attention, particularly due to the growing focus on environmental preservation. Treating wastewater effluents to mitigate environmental contamination and sustain a clean ecosystem for all living organisms is essential. Various techniques have successfully removed industrial waste, with photocatalysis emerging as a promising approach for the degradation of a diverse class of organic contaminants. Metal-free photocatalysts (MFPs) such as graphene oxide, reduced graphene and carbon nitride, and covalent organic framework are gaining popularity among scientists globally due to their low cost, high stability, and good thermal conductivity. However, traditional powdered photocatalysts present several drawbacks, such as limited capacity for light collection, inadequate surface area, poor surface oxygenation, and challenges in separation from treated water. This review discusses the fabrication processes of hybrid floatable MFP composites based on their substrates and critically evaluates their performance in degrading organic dyes and antibiotics and their application in water disinfection through specific case studies. In addition, this work highlights the potential of coupling floatable MFPs as an active component with other technologies such as ultrasonic vibration and piezoelectric effect for water remediation. Finally, this review outlines future research directions and addresses current challenges in the field.