Construction of WO3–g-C3N4 composites as efficient photocatalysts for pharmaceutical degradation under visible light

Abstract

Emerging organic contaminants (EOCs) like pharmaceuticals in the environment have become an emerging issue, which pose a threat to human health and environmental biodiversity. Many researchers have devoted their efforts to the development of novel technologies to effectively eliminate such pollutants from water cycles. In this work, we aimed to develop and employ heterogeneous WO₃–g-C₃N₄ as an efficient photocatalyst for antibiotic degradation under visible light irradiation. Synthesis of WO₃–g-C₃N₄ (WCN) composites was optimized with various g-C₃N₄ dosages and a facile hydrothermal method was used for material preparation. Sulfamethoxazole (SMX), which is one of the most commonly used antibiotics, was utilized as a model pharmaceutical to evaluate the degradation performance of the as-prepared WCN composites under visible light. Results showed that SMX removal efficiency can be largely improved by the WO₃–g-C₃N₄ composites compared to bare WO₃. In particular, the photocatalytic efficiency was raised to 91.7% when the optimized material WCN-8 was applied at a dosage of 1.0 g L⁻¹. Such enhanced photocatalytic activity can be ascribed to the formation of direct solid-state Z-scheme heterojunctions between g-C₃N₄ and WO₃, which could improve the photogenerated electron–hole pair separation efficiency as well as the redox capability. At the same time, the larger surface area and better visible light absorption capability can also contribute to the enhanced efficiency.