Construction of S-scheme heterostructured TiO2/g-C3N4 composite microspheres with sunlight-driven photocatalytic activity

In recent years, the emerging S-scheme heterojunction photocatalyst has embodied great potential in promoting the research and application of photocatalytic technology. Herein, a new TiO2/g-C3N4 S-scheme heterojunction photocatalyst (TCN-20) was constructed by decorating graphite-like carbon nitride on sea urchin-like TiO2 microspheres with a large specific surface area and a mesoporous structure. TCN-20 has excellent optical absorption ability, effective photogenerated electron-hole pair separation and very high photocatalytic degradation activity in the simulated sunlight. The degradation rate of TCN-20 for Rhodamine B reaches 96.5 %, and the reaction rate constant is 4.98 and 4.52 times higher than that of pure TiO2 and g-C3N4, respectively. Moreover, X-ray photoelectron spectra, Fermi level and band structure analyses as well as radical quenching experiments authenticate the S-scheme charge transfer mechanism of TCN-20. TCN-20 is an easy-to-prepare, non-toxic, inexpensive and promising S-scheme heterojunction photocatalyst with strong redox ability.