Preparation of nanoscale-dispersed g-C3N4/graphene oxide composite photocatalyst with enhanced visible-light photocatalytic activity

A novel metal-free photocatalyst of g-C3N4/graphene oxide nanocomposite (CNNP/GO) was fabricated by loading g-C3N4 nanoparticles on graphene oxide through electrostatic self-assembly strategy. XRD, FT-IR, SEM, TEM, and PL were adopted to analyze the structure and properties of the CNNP/GO nanocomposite. Photocatalytic activity of CNNP/GO nanocomposite was evaluated by the degradation of methylene blue (MB) under visible-light irradiation. The results show that the nanonization of bulk g-C3N4 widens the band gap of g-C3N4 from 2.75 eV to 3.40 eV, and the obtained CNNP exhibits an obvious blue-shift in the absorption band edge compared with bulk g-C3N4, resulting in the weak response to visible light. Introducing GO into CNNP can efficiently reduce the band gap to 2.55 eV, thereby enhancing the utilization of visible light. Moreover, the GO can be served as an electron acceptor in the CNNP/GO nanocomposite, leading to significantly improvement in separation efficiency of photo-generated carriers. Hence, the best photocatalytic degradation rate of MB over CNNP/GO nanocomposite is about 2 and 6 times higher than that over bulk g-C3N4 and CNNP samples, respectively. Furthermore, this work also indicates that the novel CNNP could be an excellent material to combine with other semiconductors to construct high efficient nanocomposite photocatalyst. (C) 2018 Elsevier B.V. All rights reserved.