Enhanced photocatalytic degradation of tetracycline by a H2O2-assisted Bi3NbO7/Bi2Sn2O7 composite under visible light.

ABSTRACT

A Z-scheme BNO/BSO composite photocatalyst has been successfully prepared using an in situ solvothermal method. The phase component, microstructure and optical properties of the as-prepared samples were characterized using X-ray diffractometry, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, photoluminescence spectroscopy and other means. The photocatalytic performance of the BNO/BSO composite was evaluated via the degradation of the typical antibiotic tetracycline (TC) under hydrogen peroxide assistance and visible light irradiation. The "cata + H2O2 + vis" system shows the best photocatalytic activity, and its apparent rate constant reaches 0.03164 min-1, which is 4.9 times and 5.7 times that of the "cata + vis" system and the "cata + H2O2" system, respectively. Compared with pristine that of BSO alone, the reaction rate constant of the 15% BNO/BSO composite increases 1.8 times. The enhanced photocatalytic activity is attributed to the construction of a unique Z-scheme-type heterojunction, which effectively suppresses the recombination of electron-hole pairs. In addition, the addition of H2O2 promotes the generation of more active species. Moreover, a possible photocatalytic degradation mechanism is also further proposed.