Facile Synthesis of Bi2O3/TiO2-xNx and its Direct Solar-Light-Driven Photocatalytic Selective Hydroxylation of Phenol

Mesoporous Bi2O3/TiO2-xNx nanocomposites (BiNT) have been synthesized by using a template-free homogeneous coprecipitation technique. X-ray diffraction, X-ray photoelectron spectroscopy, high-resolution transmission electron microscopy, UV/Vis diffuse reflectance spectroscopy, and photoluminescence studies are adapted to characterize the structural, electronic, and optical properties of the composites. The photocatalytic activities of the catalysts are evaluated for the hydroxylation of phenol under direct solar irradiation. The BiNT materials show excellent catalytic activity for selective phenol hydroxylation without using any oxidant. Notably, one of the nanocomposites shows a very high activity and results in a phenol conversion of 99% in aqueous medium with 100% selectivity towards hydroquinone and, in general, excellent selectivity is found for dihydroxybenzene compounds. The heterogeneous catalysts exhibit a successive slight decrease in catalytic activity if reused for five or more times.