Photocatalytic removal of volatile organic compounds by monolithic heterojunction materials: a review

Volatile organic compounds (VOCs) have become critical targets for atmospheric pollution control due to their environmental toxicity, carcinogenicity, and continuously increasing emissions. Traditional powdered photocatalysts face challenges such as mass transfer limitations, easy deactivation, and difficulty in recycling, whereas monolithic photocatalytic materials effectively address these shortcomings through carrier design. In this paper, we systematically review the research progress on monolithic materials in the field of VOC degradation in recent years. Firstly, we elucidate the reaction mechanisms and degradation pathways of P-type, Z-type, S-type heterojunctions and Schottky junctions in monolithic structures, clarifying the electron transfer modes of various heterojunctions under illumination to provide theoretical foundations for the design of high-efficiency catalysts. Furthermore, we systematically review the modification methods, performance optimization, and practical applications of various substrates, including metal foams (nickel/copper foam), metal meshes, carbon-based materials (carbon cloth, activated carbon fiber, and melamine foam), and glass substrates. We highlight that the synergistic design of substrate structures and photocatalytic active sites will be crucial for future development. This review provides theoretical support and design guidelines for the development of next-generation high-efficiency VOC treatment technologies.