Fabrication of g-C 3 N 4 /TiO 2 composite photocatalyst with extended absorption wavelength range and enhanced photocatalytic performance

Not only for utilizing both ultraviolet (UV) and visible light but also for enhancing photoinduced carriers separation capability, a composite photocatalyst composed of graphite-like carbon nitride (g-C 3 N 4 ) and TiO 2 has been successfully prepared by an acetic acid assisted sol–gel method combined with calcination process. The as-prepared g-C 3 N 4 /TiO 2 composite photocatalyst was characterized by using XRD, SEM, TEM, XPS, FT-IR spectra, UV-DRS and TGA. Combined XRD results with SEM images, it indicated that the obtained anatase TiO 2 nanoparticles dispersed well on the surface of g-C 3 N 4 sheets and the aggregation degree of TiO 2 nanoparticles could be effectively alleviated due to the introduction of g-C 3 N 4 . The results of UV-DRS further displayed that the optical absorption edge of g-C 3 N 4 /TiO 2 composites had an obvious red shift to the longer wavelength in comparison with pure TiO 2 . Profiting from the above-mentioned advantages, g-C 3 N 4 /TiO 2 composite showed excellent photocatalytic performance. Under visible light irradiation, all g-C 3 N 4 /TiO 2 composite samples had more excellent photodegradation performance than pure g-C 3 N 4 or TiO 2 , and the pseudo-first-order kinetic constant of methyl orange (MO) degradation on optimal g-C 3 N 4 /TiO 2 composite was 2.80 times as great as that on pure g-C 3 N 4 . The photodegradation performance of optimal g-C 3 N 4 /TiO 2 composite was also investigated under UV–vis light irradiation. Compared with the pure phase (TiO 2 or g-C 3 N 4 ), the composite photocatalytic capability was remarkably enhanced by coupling TiO 2 with g-C 3 N 4 , which mainly benefited from the effective separation of photoinduced electron–hole pairs and the extended optical absorption range, both owing to the heterojunction built-in between g-C 3 N 4 and TiO 2 .