Graphitic carbon nitride (g-C3N4)–Pt-TiO2 nanocomposite as an efficient photocatalyst for hydrogen production under visible light irradiation

Abstract

Porous graphitic carbon nitride (g-C₃N₄) was prepared by a simple pyrolysis of urea, and then a g-C₃N₄–Pt-TiO₂ nanocomposite was fabricated via a facile chemical adsorption followed by a calcination process. The obtained products were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, UV-vis diffuse reflectance absorption spectra, and electron microscopy. It is found that the visible-light-induced photocatalytic hydrogen evolution rate can be remarkably enhanced by coupling TiO₂ with the above g-C₃N₄, and the g-C₃N₄–Pt-TiO₂ composite with a mass ratio of 70 : 30 has the maximum photoactivity and excellent photostability for hydrogen production under visible-light irradiation, and the stable photocurrent of g-C₃N₄–TiO₂ is about 1.5 times higher than that of the bare g-C₃N₄. The above experimental results show that the photogenerated electrons of g-C₃N₄ can directionally migrate to Pt-TiO₂ due to the close interfacial connections and the synergistic effect existing between Pt-TiO₂ and g-C₃N₄ where photogenerated electrons and holes are efficiently separated in space, which is beneficial for retarding the charge recombination and improving the photoactivity.