Inativação de fotoeletroquímica de microrganismos sobre filmes de Óxido de Zinco dopado com Nitrogênio

Abstract

Zinc oxide (ZnO) is an n-type semiconductor that has been investigated in various fields, including modern technologies involving water treatment, photovoltaic devices, and inhibition of bacteria and fungi. The optical and catalytic properties of ZnO can be altered by introducing dopants into the semiconductor crystal lattice. In this study, we investigated the structural, optical, and photoelectrochemical properties of ZnO films and nitrogen-doped ZnO (ZnO:N) films prepared by electrochemical deposition. The films were prepared with different doping concentrations, based on the control of the N2 flow during synthesis (20, 40, and 60 cm3 min-1 ). X-ray diffraction patterns showed that both ZnO and ZnO:N films, after thermal treatment, have a wurtzite structure. The presence of nitrogen altered the values of the bandgap energy (Ebg) from 3.34 to 3.17 eV, estimated by the Wood-Tauc method, for ZnO and ZnO:N samples, respectively. Photoelectrochemical studies showed higher photocurrent density for ZnO:N compared to ZnO films, reaching 60 µA cm-2 at 0.70 V (vs. Ag/AgCl). Chronopotentiometry curves demonstrated that all films exhibit n-type semiconductor behavior, suitable for oxidation processes. The flat-band potentials of ZnO and ZnO:N samples indicate that the electrodes have suitable potentials for generating reactive oxygen species capable of inactivating microorganisms. In antimicrobial activity tests, all ZnO:N films inhibited Staphylococcus aureus. For Escherichia coli, ZnO:N-40 and ZnO:N-60 films exhibited better inhibitory activity. In the evaluation of antifungal activity against the yeast Candida albicans, the ZnO:N-40 film demonstrated the best inhibition.