Desenvolvimento de fotoanodos de TiO₂ para fotoeletrocatálise: efeito da sensibilização com pontos de carbono, pontos quânticos de CdTe ou nanopartículas de prata.

Abstract

The increasing presence of recalcitrant pollutants in water bodies has driven the development of advanced technologies for wastewater treatment. In this context, photoelectrocatalysis has emerged as a promising alternative by combining photocatalytic and electrochemical processes, promoting the separation of photogenerated charge carriers and enhancing the degradation efficiency of contaminants. This study aimed to develop and evaluate nanostructured titanium dioxide (TiO₂)-based photoanodes modified with different nanomaterials for application in the photoelectrocatalytic degradation of Rhodamine B, used as a model pollutant. Pure TiO₂ photoanodes and photoanodes modified with carbon dots (CDs), quantum dots (QDs) of CdTe, and silver nanoparticles (AgNPs) were prepared and deposited onto fluorine-doped tin oxide (FTO)-coated glass substrates. The systems were evaluated in a laboratory-scale photoelectrochemical reactor under ultraviolet irradiation and an applied external potential. The degradation efficiency was monitored by UV–Visible spectroscopy through the reduction of the characteristic absorbance of Rhodamine B. The results demonstrated that photoelectrocatalysis exhibited superior performance compared with conventional photocatalysis, highlighting the contribution of the applied electrical potential to reducing electron–hole pair recombination. Among the evaluated materials, the pure TiO₂ photoanode achieved the highest degradation efficiency, reaching the lowest residual dye concentration at the end of the process, approximately 2.00 × 10⁻⁷ g/mL. The photoanodes modified with CDs and QDs also promoted the degradation of Rhodamine B; however, they exhibited lower performance than unmodified TiO₂ under the experimental conditions employed, with final concentrations of 3.88 × 10⁻⁷ g/mL and 2.73 × 10⁻⁷ g/mL, respectively. The results indicate that the effectiveness of the modifiers depends on factors such as concentration, surface distribution, and charge transfer, emphasizing the need for further studies to optimize these systems. Therefore, this work contributes to the development of photoelectrocatalytic technologies for the treatment of contaminated water and to advancing the application of nanomaterials in environmental processes.