An S-scheme TiO2/g-C3N4 nanocomposite effectively degrades phenanthrene under visible light

It is a challenge to effectively degrade phenanthrene (PHE) pollutants, which are widely present in aquatic environments, in order to reduce harm to humans and ecosystems. In this study, an S-scheme TiO₂/g-C₃N₄ photocatalytic system is constructed using 0D TiO₂ nanospheres and 2D g-C₃N₄ nanosheets for the removal of PHE from water under sunlight irradiation. The effects of irradiation time, quality ratio of TiO₂ to g-C₃N₄, and cycle time on the performance of the TiO₂/CN photocatalyst are investigated. The experimental results show that the ratio of TiO₂ to g-C₃N₄ significantly affects the photocatalytic activity of the photocatalyst. Under the optimal ratio of TiO₂ to g-C₃N₄ (50 % TiO₂/CN), the apparent reaction rate constant for phenanthrene reached 0.00796 min⁻¹, which is 11.5 times higher than that of pure TiO₂ (0.00069 min⁻¹). The tests of optical performance and photoelectrochemical properties further confirmed that the construction of the TiO₂/g-C₃N₄ S-type photocatalyst successfully enhanced the spatial separation efficiency of photogenerated carriers and ensured a continuous supply of energy during the redox reaction process. Converting highly toxic phenanthrene into a non-toxic green degradation product provides an practical strategy for the safe treatment of PHE in aqueous environments through the use of visible-light-driven heterojunction photocatalysts. Additionally, the data collected on phenanthrene degradation in this study will provide valuable references for developing degradation methods for other PAHs, such as naphthalene, anthracene, and pyrene.