Bi₂Fe₄O₉/rGO nanocomposite with visible light photocatalytic performance for tetracycline degradation

Bismuth-iron semiconductor materials have been widely studied in the photocatalytic field due to their excellent light responsiveness. Among them, the potential and mechanism regarding photocatalytic degradation of organic pollutants by Bi2Fe4O9 are seriously ignored. In this research, Bi2Fe4O9/reduced graphene oxide (BFO/rGO) was successfully synthesized for tetracycline (TC) removal. Under visible light irradiation, the TC degradation efficiency reached 83.73% within 60 min, which was much higher than that of pure BFO or rGO. The impacts of crucial factors (TC initial concentration, humic acid concentration, pH value and inorganic anions) were systematically analyzed. The photoelectric performance experiments indicated that the addition of rGO decreased the electron-hole pair recombination efficiency and improved the charge transfer efficiency, thus significantly enhancing the photocatalytic performance. According to quenching experiments and EPR (Electron Paramagnetic Resonance) analysis, superoxide radical (center dot O-2(-)) and hole (h(+)) were determined as the main active species during degradation reactions. Eventually, the possible degradation routes of TC were presented by identifying intermediates.