Generalized one-pot synthesis, characterization, and photocatalytic activity of hierarchical BiOX (X = Cl, Br, I) nanoplate microspheres

A general one-pot solvothermal process was explored to prepare BiOX (X = Cl, Br, I) powders by employing ethylene glycol as the solvent. The as-prepared BiOX powders were characterized by X-ray powder diffraction, scanning electron microscopy' transmission electron microscopy, high-resolution transmission electron microscopy, UV-vis diffuse reflectance spectroscopy, and nitrogen sorption. The resulting BiOX samples were phase-pure and of hierarchical microspheres consisting of nanoplates. The band gaps of the as-prepared powders were estimated to about 3.22, 2.64, and 1.77 eV for BiOCl, BiOBr, and BiOI, respectively. On the basis of characterization results, we proposed a possible process for the growth of hierarchical BiOX nanoplate microspheres. Moreover, we evaluated their photocatalytic activities on the degradation of methyl orange and compared them with TiO2 (Degussa, P25) under UV-vis light irradiation and C-doped TiO2 under visible light (lambda > 420 nm) irradiation, respectively. It was found that all the BiOX samples were photocatalytically active and BiOI exhibited excellent activity under both UV-vis and visible light irradiation. The resulting hierarchical BiOX nanoplate microspheres are very promising photocatalysts for degrading organic pollutants and other applications.