N doped -TiO2 coupled to BiVO4 with high performance in photodegradation of Ofloxacin antibiotic and Rhodamine B dye under visible light

Abstract

BiVO4 coupled to N-Doped TiO2 were obtained using the sol gel method assisted by microwave. Double modifications of TiO2 by doping with nitrogen and BiVO4 were induced to improve the UV visible response of TiO2 and improves the separation of generated charge carriers. The structural and morphological analyses support the formation of uniform BiVO4 and N-TiO2 heterostructures, with the surface area significantly increased by approximately 2.5 times in comparison with the bare TiO2. Doping with N and BiVO4 shifted the TiO2 band gap energy from 3.2 eV to around 2.4 eV. The photocatalytic activities of the catalysts were evaluated in the degradation reaction of Rhodamine B and Ofloxacin in aqueous solution. The resulting structures showed superior photocatalytic activity compared to their individual counterparts. More than 98% and 92% of Rhodamine B and Ofloxacin, respectively, could be degraded with the most active BiVO4/N-TiO2 catalyst under visible light radiation. The enhanced photocatalytic activity displayed by the heterostructures could be explained in terms of higher absorption of visible light due to the synergistic effect of N-doping of TiO2 and BiVO4 coupling and improved charge separation due to the formation of an n–n junction at the interface of N-TiO2 and BiVO4 semiconductors. The showed enhance photocatalytic response for the degradation for both pollutants was attributed to electrons and holes from photo-oxidation by ROS, confirmed by carrier scavenger experiments. The separation efficiency of photoinduced charge carriers was further affirmed by photoluminescence and electrochemical studies. The structures were stable even after the third catalytic cycle, indicating their efficiency in potential treatments of pollutants. Finally, based on experimental and test results, a reaction mechanism was proposed.