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 sp² 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