Synthesis and Characterization of BaAl2O4 Catalyst and its Photocatalytic Activity Towards Degradation of Methylene Blue Dye

Hexagonal BaAl2O4 catalyst has been prepared using a gamma-ray irradiation assisted polyacrylamide gel method. The catalysts synthesized at different calcining temperatures were analyzed to insight into their effects on the structural, crystalline, surface morphology, color, optical, fluorescence and photocatalytic properties of the hexagonal BaAl2O4 catalyst. Increasing the calcining temperature has obvious influences on the crystallinity, color, optical properties and the formation of the hexagonal BaAl2O4 catalyst. The optical energy gap (Eg) value of the hexagonal BaAl2O4 catalyst increases with the increasing of calcining temperature. TEM image of the pure hexagonal BaAl2O4 catalyst shows a morphology of flake structure and aggregation. Raman spectroscopy of the pure hexagonal BaAl2O4 catalyst exhibits four luminescent background peaks at 400, 415, 428 and 445 nm mainly due to the oxygen vacancies (V-O), Ba vacancies (V-Ba) and some color centers exists in the BaAl2O4 sample. A comparison of photocatalytic activity among samples for degradation of methylene blue (MB) dye indicates that the pure hexagonal BaAl2O4 catalyst exhibits highest photocatalytic activity under the irradiation of both visible and ultraviolet light. Based on the fluorescence experiment, electrochemical and active species tests, the high photocatalytic activity of the pure hexagonal BaAl2O4 catalyst to be related to hole (h(+)) and hydroxyl radical (center dot OH) and also to the defects in the sample.