Controlled ultrasonic synthesis of TiO2@C3N4 nanocomposites with porphyrin as a solid-state electron mediator: A promising material for pollutant discoloration under visible light

This work describes a new ternary nanocomposite of TiO2 nanospheres decorated on the surface of graphitic carbon nitride (C3N4)-porphyrin (TCP) via the sonochemical method (WUC-D22H, Daihan Scientific, Korea). The ultrasonic frequency and power were 20 kHz and 100 W, respectively. The structure and morphology of the synthesized nanocomposites were systematically characterized by FT-IR, XRD, SEM, UV-DRS, and mapping analysis. Compared to its single and binary components, the ternary nanocomposite TiO2@C3N4-TCP clearly shows higher photocatalytic action against Rhodamine B (Rh-B) dye contaminants in the visible region. Ternary nanocomposite TiO2@C3N4-TCP catalysts have good stability and reusability for four successive photocatalytic discoloration tests. These materials consist of synergistic nanocomposites with enhanced visible light adsorption, effective charge separation, and low rate recombination dynamics. In addition, it has been clarified that hydroxyl and superoxide radical active species play some auxiliary roles, whereas the holes play the main role in the photodiscoloration of Rh-B. Moreover, as expected this work presents a novel approach towards advanced ternary nanocomposites in visible light adsorption aimed at the photodecomposition of pollutants via the photocatalytic process.