Effective improvement of photocatalytic hydrogen evolution via a facile in-situ solvothermal N-doping strategy in N-TiO2/N-graphene nanocomposite

Nanocomposite NTNG composed of nitrogen-doped titanium dioxide (N-TiO2) and nitrogen-doped graphene (N-graphene) is synthesized to increase the photocatalytic efficiency for hydrogen production through a convenient in-situ solvothermal nitrogen-doping strategy. TEM and AFM images suggested that NTNG nanosheet consists of approximately 1–5 layers by folding its own sheet and that the wrinkled multilayer textures are stretched to a large extent due to the uniformly anchored N-TiO2 nanoparticles on N-graphene surface effectively avoiding the aggregation. XPS results indicated that the in-situ solvothermal nitrogen-doping not only allows the nitrogen-doping of TiO2 but also further changes the nitrogen-doping state of N-graphene including the nitrogen content and the ratio of dopant types. Raman spectroscopy told us that N-graphene in NTNG is more ordered than separate N-graphene due to fewer defects from the improved sp2-hybridized nitrogen. As a result, the photocatalytic efficiency of NTNG under ultraviolet irradiation is improved about 13.1 times compared to commercial P25.