Abstract:

A hybrid catalyst of g-C₃N₄ (graphitic carbon nitride)/rGO (reduced graphene oxide) was prepared by directly heating a mixture of melamine and GO in air. g-C₃N₄ in the hybrid retained the structure of pristine g-C₃N₄, and the heterojunction between g-C₃N₄ and rGO was formed by π-π interaction. The highest photocatalytic efficiency for the degradation of rhodamine B (RhB) was with the melamine/GO mass ratio of 800/1, with a first order rate constant 2.6 times that of pristine g-C₃N₄. The enhanced photocatalytic activity was assigned to the rGO-promoted separation of photo-generated electron (e^-)-hole (h⁺) pairs. In addition, the photocatalytic activity of g-C₃N₄/rGO was pH sensitive with a much increased photodegrading rate at low pH values. The first order rate constant was 8.6 times that of pristine g-C₃N₄ at pH = 1.98. The pH sensitive behavior resulted from the promoted oxidation of h⁺ with RhB by the consumption of e^- with the reaction of proton (H⁺) in which rGO acted as a good platform for transferring e^- through its atomic sheets.

Key words: Graphitic carbon nitride, Graphene oxide, Photocatalysis, pH-sensitivity, Rhodamine B degradation