Atomically Pt implanted nanoporous TiO₂ film for photocatalytic degradation of trace organic pollutants in water

Trace organic pollutants in water can potentially and persistently impart destructive effects on human body and it is difficult to remove them by conventional treatment process owing to their low concentration. Herein, considering the importance and difficulty, a novel atomically N implanted nanoporous TiO2 film was prepared using a facile immersion and reduction method and confirmed by X-ray diffraction (XRD), X-ray photoelectron spectra (XPS), field-emission scanning electron microscope (FESEM), aberration-corrected high-angle annual dark-filed scanning transmission electron microscopy (HAADF-STEM), high resolution transmission electron microscopy (HRTEM), X-ray absorption near-edge structure (XANES) and extended X-ray absorption fine structure (EXAFS). The platinum single-atom photocatalyst exhibited considerable performance and good stability for vacuum ultraviolet (VUV) and ultraviolet (UV) photocatalytic degradation of ethenzamide, one of the typical trace organic pollutants in water, and the removal rate of ethenzamide reached 94.52% and 100% under VUV irradiation when residence time was only 0.5 min and its initial concentrations were 500 ppb and 100 ppb, respectively. The corresponding photocatalytic degradation ratios were 2.19 and 3.98 times those by pristine nanoporous TiO2 film, respectively and energy consumption was only 0.46 kWh/m(3), which was about 28% that by pristine nanoporous TiO2 film. 84.44% of ethenzamide was degraded under UV irradiation when the initial ethenzamide concentration was 500 ppb and residence time was 24 min. Mass transfer resistance coming from low concentration was effectively overcome owing to eddy diffusion accelerated by the nanopores on the surface of TiO2 film and molecular diffusion of trace pollutants promoted by N single atoms. The development of the platinum single-atom photocatalyst has great significance for highly efficient removal of trace organic pollutants in water.