Catalytic photo-degradation of brilliant green and bacterial disinfection of Escherichia coli by the action of Y2Ti2O7/AgO films

Abstract

In this study, we evaluated the photocatalytic efficacy of pure Y2Ti2O7 films incorporating varying AgO ratios (1.0, 3.0, and 5.0 mol%) in the degradation process of brilliant green dye and in the bacterial disinfection of Escherichia coli under UV–visible illumination. The films were prepared utilizing a photochemical methodology involving β-diketonate complexes of Y(dbm)3, Ti(dbm)4, and Ag(acac) as starting materials. Following synthesis, the photo-deposits underwent calcination at 900 °C for 2 h and were subsequently analyzed using Fourier Transform Infrared Spectroscopy, X-Ray diffraction, Scanning Electron Microscopy - Energy Dispersive X-ray Spectroscopy, and X-ray Photoelectron Spectroscopy. The outcomes of these characterizations indicate the formation of a pyrochlore Y2Ti2O7 cubic phase, with the emergence of AgO in the doped samples. Photocatalytic performance yielded significant results, with a 94.9 % degradation of brilliant green observed for Y2Ti2O7 samples doped at 3.0 mol%, and a 98.4 % inhibition of Escherichia coli cultures observed for Y2Ti2O7 samples doped at 1.0 mol%. Theoretical calculations were employed to determine the band edge potentials of both oxides, supporting the establishment of a type I heterojunction between the Y2Ti2O7 phase and AgO. A degradation mechanism has been postulated based on assays involving the blocking of reactive oxygen species and charge carriers through the use of specific inhibitors.