A Bi2O3/carbon composite as a short-circuited cell for water purification

A carbon/bismuth oxide C/Bi₂O₃ composite arrangement is demonstrated to function as a short-circuited cell for wastewater treatment. Bismuth oxide nanoparticles were deposited on carbon felt (CF) surfaces using three deposition techniques: doctor blade, drop coating and physical vapor deposition (PVD). The structural, microstructural and optical properties of the resulting composites were obtained to evaluate the electrical contact between Bi₂O₃ and carbon felt. Cyclic voltammetry (CV) was employed to assess the photoanodic and cathodic nature of Bi₂O₃ and carbon, respectively. Although the C/Bi₂O₃ arrangement as well as the separate composite materials were found to be capable of producing reactive oxygen species (ROS), the C/Bi₂O₃ photocurrent density j was substantially higher when compared to that of the separate materials. The efficiency of the short-circuited cell (C/Bi₂O₃) was evaluated for the degradation of a model organic pollutant under dark and visible light and under anoxic and oxygen-saturated atmospheres. Remarkably, the short-circuited C/Bi₂O₃ system achieved 70–90 % pollutant degradation within the first 10 min. Quantification of ^•OH radicals and H₂O₂ evolution indicated that both cathodic and anodic reactions contribute to ROS generation in the photo-assisted C/Bi₂O₃ cell. Notably, pollutant degradation occurred not only in the absence of light, but also under both anoxic and oxygen saturated conditions. The proposed electron transfer and reaction mechanisms are based on the measured band edge potentials (E_CB and E_VB) of Bi₂O₃ and carbon from Mott-Schottky analysis. This electrically coupled C/Bi₂O₃ composite represents an innovative strategy with significant technological potential for solar-light-activated advanced oxidation processes for wastewater treatment applications.