pH-regulated hydrothermal synthesis and characterization of Sb 4 O 5 X 2 (X = Br/Cl) and its use for the dye degradation of methyl orange both with and without light illumination.

A pH-regulated hydrothermal synthesis method was employed to synthesize Sb 4 O 5 Br 2 and Sb 4 O 5 Cl 2 crystallites. Characterization is done by single crystal X-ray diffraction, powder X-ray diffraction, infra-red spectroscopy, scanning electron microscopy and DFT studies. The compounds crystallize in monoclinic symmetry with a P 2 1 / c space group. Complete structural analysis of the Sb 4 O 5 Br 2 compound by using single crystal X-ray diffraction data is performed for the first time and a comparative study with Sb 4 O 5 Cl 2 is also discussed. The SEM study reveals that the surface morphology changes with the variation of pH for bromide compounds, whereas pH change does not affect the morphology of the chloride analogues. Electronic band structures of the synthesized oxyhalides were investigated in order to understand their catalytic effects in the dye degradation reactions in dark as well as sunlight conditions.