Improved photocatalytic property of peony-like InOOH for degrading norfloxacin

Novel peony-like InOOH photocatalyst was firstly obtained with the help of glycerol in the solvothermal process, whose optimal proportion of glycerol was determined to be 25%. X-ray diffraction, scanning electron microscope, X-ray energy dispersion spectrum, transmission electron microscopy, X-ray photoelectron spectroscopy and UV–visible diffusion reflectance spectrum were obtained and analyzed to reveal the structure, morphology, physical and chemical properties of synthesized samples. The results indicated that the synthesized InOOH was orthorhombic structure with the peony-like morphologies, whose average particle size was 2–5 µm approximately. The band-gap of the peony-like InOOH was estimated to be 3.65 eV. The photocatalytic activities of the samples were investigated by degrading norfloxacin under UV-light irradiation, which followed the first-order reaction kinetics. The degradation efficiency of peony-like InOOH could reach up to 98.84%. And the first order kinetic constant of peony-like InOOH was 0.01519 min−1, which was about 4.8 times or 1.7 times than that of hexagram-like InOOH or InOOH nanosheet. The peony-like InOOH showed the most superior photocatalytic performance compared with hexagram-like InOOH and InOOH nanosheet, which originated from its high separation efficiency and low recombination rate of photoproduction electron-hole pairs. The reduction of total organic carbon revealed the mineralization of norfloxacin during the photocatalytic process. Finally, O2− radicals were proved to be main reactive species during the degradation process of norfloxacin. Furthermore, the degradation pathway and the degradation mechanism of norfloxacin with peony-like InOOH as catalyst were discussed in detail.