Nitrogen-doped CeO_x nanoparticles modified graphitic carbon nitride for enhanced photocatalytic hydrogen production

Nitrogen-doped CeO_x nanoparticles (N-CeO_x NPs) were directly formed on graphitic carbon nitride (g-C₃N₄) via a facile one-pot method by annealing a mixture of Ce(NO₃)₃ and melamine as CeO_x and g-C₃N₄ precursors, respectively. Nitrogen was in situ doped into CeO_x under NH₃ atmosphere released by the decomposition of melamine during the annealing process. The physical and photophysical properties of N-CeO_x NPs modified g-C₃N₄ photocatalysts were investigated to reveal the effects of N-CeO_x NPs on the photocatalytic activities of g-C₃N₄. It was found that the one-pot annealing method was favorable for forming intimate interfacial contact between N-CeO_x and g-C₃N₄. The visible light photocatalytic hydrogen production activity over g-C₃N₄ was enhanced by ca. 1.2 times with the N-CeO_x NPs modification. The significant enhancement in photocatalytic performance for the N-CeO_x/g-C₃N₄ heterojunction should be mainly because of the promoted charge transfer and charge separation between N-CeO_x NPs and g-C₃N₄ resulting from the intimate interfacial contact and Type II band alignment. In addition, the improved visible light absorption of N-CeO_x NPs induced by nitrogen doping could be another reason for the enhanced photocatalytic activity of the N-CeO_x/g-C₃N₄ heterojunction.