TiO₂ nanoparticles-functionalized N-doped graphene with superior interfacial contact and enhanced charge separation for photocatalytic hydrogen generation.

Titanium dioxide (TiO2) nanoparticles-functionalized N-doped graphene (NGR) composites (NGR/TiO2) were prepared through solvothermal treatment approach using exfoliated NGR and tetrabutyl titanate as the staring materials. The composites were characterized by transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, UV-vis diffuse reflectance spectra, photoelectrochemical, and electrochemical measurements. Nitrogen doping provides favorable nucleation and anchor sites for TiO2 nanocrystals formation on NGR sheets, helping to form an intimate interfacial contact between NGR and TiO2 nanoparticles. Moreover, NGR has higher electrical conductivity than the reduced graphene oxide (RGO) due to the recovery of the sp(2) graphite network and decrease of defects, resulting in more effective charge transfer and charge separation in the NGR/TiO2 composite. NGR/TiO2 nanocomposite demonstrated a higher photocatalytic activity for hydrogen production as compared to its counterpart, TiO2-functionalized RGO composite (RGO/TiO2). This work provides new insights to design new more efficient graphene-based nanocomposite photocatalysts for solar energy conversion.