A novel metal-free nanomaterial P-CN/BC/NCDs preparation and its performance of photocatalytic degradation

The development of photocatalysts with high charge separation and migration efficiencies for environmental remediation using sunlight had been a research priority. In this study, a ternary composite photocatalyst, P-CN/BC/NCDs, was successfully synthesized by thermal condensation and hydrothermal methods, incorporating graphitic carbon nitride (P-CN), biochar (BC), and nitrogen-doped carbon quantum dots (NCDs). Alizarin red S (ARS) was selected as the model pollutant to evaluate the photocatalytic degradation performance. P-CN/BC/NCDs exhibited enhanced photocatalytic degradation performance under visible light irradiation, with a 4.5-fold improvement compared to P-CN alone. The optimally NCDs-loaded P-CN/BC nanocomposites exhibited high visible light absorption and high specific surface area. The increased photocatalytic activity was further confirmed by the increase in photocurrent intensity and the decrease in fluorescence intensity and resistance. XPS and FT-IR tests showed that NCDs, as co-catalysts of P-CN/BC, effectively promoted charge separation through ether bonds and electrostatic interactions. It was experimentally verified by free radical trapping experiments and EPR tests that •O₂⁻ was the primary active species in the photocatalytic process, while •OH served as an auxiliary site during the degradation process. Cyclic experiments demonstrated high reusability and excellent stability, with an activity exceeding 93.8 %. Decomposition intermediates and reaction pathways were identified by liquid-quality analysis. Photocatalyst pervasiveness was evaluated by using different pollutants including methyl orange (MO), rhodamine B (Rh B) under similar conditions. This design concept of functional synergistic modification of P-CN materials holds promise for application in various fields.