Construction of (001)-TiO₂/g-C₃N₄ heterojunction for enhanced photocatalytic degradation of methylene blue

The (001)-TiO₂ (001 crystal plane-oriented titanium oxide) nanoparticles was precipitated on the surface of as-prepared graphitic carbon nitride (g-C₃N₄) and the composites with heterogeneous structures were manufactured. Methylene blue (MB) as the target pollutant was used to evaluate the performance of the composite photocatalysts. The decrease of the band gap, suppression of electron–hole recombination and the increased specific surface area of the composites enhance the the photocatalytic degradation performance. The mass ratio of (001)-TiO₂ and g-C₃N₄ in the composites with the best degradation performance for MB was found to be 1:5, which was denoted as TCN2. The rate for MB to be degraded after exposure to light for 60 min was 95% by TCN2. The degradation rate constant k of TCN2 is 0.0442 min⁻¹, which is 7 times that of (001)-TiO₂ and 4 times that of g-C₃N₄. After four rounds of photocatalytic experiments, the photocatalytic efficiency of TCN2 remains at a high level. The composition and microstructure of the materials were characterized by XRD, XPS, FTIR, SEM, TEM, and BET. The optical properties and degradation mechanism of the material were investigated by PL, DRS, PEC, EIS, and active substance capture experiments. The mechanism of MB photocatalytic degradation was proposed.