Research Progress on Novel Semiconductor Photocatalysts for Degrading VOCs

Volatile organic compounds (VOCs) pose significant health risks. Photocatalytic oxidation offers a promising route for VOC purification under ambient conditions. Based on a review of over 80 studies, this article critically evaluates research progress on four semiconductor photocatalyst systems (TiO2-based, g-C3N4-based, bismuth-based oxides, and MOFs) for VOC degradation. Unlike traditional descriptive reviews, this work establishes a quality-based filtering framework to distinguish studies reporting standardized photochemical parameters from those that do not. The analysis reveals a fundamental problem: the vast majority of reviewed studies lack essential parameters (incident photon flux, apparent quantum yield, or rigorous dark adsorption equilibrium), rendering cross-study comparisons invalid. Most literature relies on non-standardized metrics such as conversion percentages or rate constants per catalyst mass. While some high-quality studies report AQY, these remain a small fraction of the literature. Within individual studies under identical conditions, modification strategies enhance activity relative to controls, but relative efficiency (ζr) values are meaningful only within the same study and cannot be compared across setups. This review thus serves a dual purpose: to summarize modification strategies and to critically expose the lack of standardization. Future research must adopt unified reporting standards (photon flux, AQY, benchmarks under identical conditions) to transform the field into a reproducible, cumulative science.