Synthesis and characterization of graphene–N-doped TiO₂ nanocomposites by sol–gel method and investigation of photocatalytic activity

In this study, graphene–nitrogen-doped TiO₂ (GR–N/TiO₂) nanocomposites have been successfully synthesized by sol–gel method. For synthesis of these nanocomposites have been used from triethylamine N(CH₃CH₂)₃ as precursors of nitrogen, titanium tetraiso-propoxide (TTIP) Ti[OCH(CH₃)₂]₄ as precursors of titanium and graphene sheets. The resulting GR–N/TiO₂ nanocomposites are characterized by X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FT-IR), Scanning Electron Microscopy (SEM) and Energy Dispersive of X-ray Spectroscopy (EDS). The optical properties are studied using UV–Vis diffuse reflectance spectroscopy (DRS), which confirms that the spectral responses of the nanocomposite catalysts are extended to the visible light region and show a significant reduction in band gap energy from 3.26 to 2.9 eV. Photoluminescence (PL) emission spectra verify that GR–N/TiO₂ nanocomposites possess better charge separation capability than pure TiO₂ and N-doped TiO₂. The photocatalytic activity is tested by degradation of methyl orange (MO) as a model textile dye under UV and visible light irradiation. The results demonstrate that GR–N/TiO₂ nanocomposites can effectively photodegrade MO, showing an impressive photocatalytic enhancement over pure TiO₂. The facile preparation of these nanocomposites and their improved photocatalytic activities suggest that these materials can have a promising future for water and wastewater purifications.