Fabrication of Co3O4 and Au co-modified BiOBr flower-like microspheres with high photocatalytic efficiency for sulfadiazine degradation

For the first time, we fabricated Au-BiOBr-Co3O4 hierarchical flower-like microspheres by hydrothermal and photo-deposition methods. Au and Co3O4 nanoparticles (NPs) were selectively deposited on the {0 0 1} and {1 1 0} facets of BiOBr nanopetals, respectively. The light absorption, photoluminescence (PL), and electrochemical analyses revealed that the selectively deposited Au and Co3O4 can effectively enhance both the visible-light absorption and charge carrier separation in space. The photocatalytic degradation of sulfadiazine (SD) indicated that the degradation of SD follows the pseudo-first-order reaction and the reaction rate constant was increased 17 times from BiOBr flower-like microspheres (0.00014 min(-1)) to Au and Co3O4 co-modified Au-BiOBr-Co3O4 flower-like microspheres (0.00254 min(-1)). From the high performance liquid chromatographymass spectrometry (HPLC-MS) measurement, it was disclosed that the desulfonated and bromized products are the main intermediates during SD degradation over Au-BiOBr-Co3O4. Meanwhile, the reactive species trapping experiments confirmed that Au-BiOBr-Co3O4 can produce h(+) , O-center dot(2)-, and Br-0 reactive species responsible for antibiotic degradation. On the basis of these experiment results and discussion, the degradation mechanism of SD over Au-BiOBr-Co3O4 was tentatively discussed. We think this work provides a reference to fabricate novel photocatalytic materials for the effective degradation of antibiotics.