Series of Pt-N/TiO2 photocatalysts were synthesized using the sol-gel method. The photocatalysts' characteristics by X-ray diffractometry (XRD), scanning transmission electron microscopy (STEM), diffuse reflectance spectroscopy (DRS), X-ray photoelectron spectroscopy (XPS) showed that sample with the molar ratio Ti:N equal 1:4 and platinum nanoparticles size of about 3 nm had anatase structure, about 94 m(2)/g specific surface area and nitrogen content about 0.7 at.%. The photocatalytic activity was estimated by measuring the decomposition rate of phenol in 0.2 mM aqueous solution under Vis and UV/Vis light irradiation. Compared to N-TiO2 and Pt-TiO2 samples, the photocatalytic activity was improved markedly for samples Pt-N/TiO2 regarding the observed synergistic effect of nitrogen and platinum. The formation of hydroxyl radicals ((OH)-O-center dot) on the surface of Pt-N/TiO2 nanocomposites was detected by the luminescence technique using terephthalic acid as probe molecules. Regarding flow back fluid treatment after shale gas exploration, the progress of photocatalytic degradation of organic compounds was measured by the total organic carbon (TOC) concentration. (C) 2015 Published by Elsevier B.V.