Enhanced visible-light photocatalytic activity of g-C3N4/TiO2 films

• Visible-light-driven g-C3N4/TiO2 composite films are successfully prepared.
• The visible-light photo catalytic activity of TiO2 is remarkably improved by g-C3N4 loading.
• The optimum g-C3N4 loading amount is about 50 wt%.
• Enhanced activity is ascribed to the improved light harvesting of the g-C3N4/TiO2 composite.
• Electron–hole separation process at the g-C3N4/TiO2 interface is proposed.

Enhanced photocatalytic degradation of methylene blue (MB) using graphitic carbon nitride/titanium dioxide (g-C3N4/TiO2) catalyst films has been demonstrated in this present work. The g-C3N4/TiO2 composites were prepared by directly heating the mixture of melamine and pre-synthesized TiO2 nanoparticles in Ar gas flow. The g-C3N4 contents in the g-C3N4/TiO2 composites were varied as 0, 20, 50 and 70 wt%. It was found that the visible-light-induced photocatalytic degradation of MB was remarkably increased upon coupling TiO2 with g-C3N4 and the best degradation performance of ∼70% was obtained from 50 wt% g-C3N4 loading content. Results from UV–vis absorption study, Electron microscopy, Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy suggest that the improved photoactivity is due to a decrease in band gap energy, an increased light absorption in visible light region and possibly an enhanced electron–hole separation efficiency as a result of effective interfacial electron transfer between TiO2 and g-C3N4 of the g-C3N4/TiO2 composite film. Based on the obtained results, the possible MB degradation mechanism is ascribed mainly to the generation of active species induced by the photogenerated electrons.

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