Facile synthesis of AgNPs modified TiO2@g-C3N4 heterojunction composites with enhanced photocatalytic activity under simulated sunlight

Herein, TiO2/g-C3N4/Ag (TCA) composites were successfully fabricated by a simple two-step method and wet chemical reduction. Titanium isopropoxide and melamine were used as precursors to prepare TiO2/g-C3N4 heterojunction composites by simple stirring and calcining. Then, different mass fractions of AgNPs were decorated on the surface of the above composites by wet chemical reduction to obtain a sequence of TiO2/g-C3N4/Ag (TCA) composites. TCA composites were analyzed by XRD, TEM, HRTEM, EDS, XPS, BET, Raman spectroscopy, PL spectrum and UV-vis diffuse reflectance spectrum. The results showed that TCA composites had remarkable enhancement in the separation of photogenerated carriers and the utilization of light, which was as result of the coordination of the three components. For photodegradation of RhB or phenol under simulated sunlight, TCA-1 samples revealed the best photocatalytic degradation performance, and the corresponding degradation rates were 91.4% at 60 min and 90.0% at 120 min, respectively. Moreover, TCA-1 composites maintained superior degradation performance after reusability tests, indicating that TCA-1 composites had excellent photochemical stability. For experimental results, a possible photodegradation mechanism of TCA composites was also proposed.