Visible-light enhanced azo dye degradation and power generation in a microbial photoelectrochemical cell using AgBr/ZnO composite photocathode

In this study, a dual-chamber microbial photoelectrochemical cell (MPEC) composed of a bio anode and a photoresponse AgBr/ZnO-modified graphite as a photocathode was investigated. The cell efficacy in degrading reactive black 5 (RB5), a diazo dye, in the cathodic chamber and simultaneously, electricity generation was analyzed. The synthesized AgBr/ZnO photocatalyst was characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), UV-vis diffuse reflectance spectra (UV-vis DRS), photoluminescence (PL), linear sweep voltammetry (LSV), and electrochemical impedance spectroscopy (EIS). Under light irradiation, the MPEC equipped with AgBr/ZnO-modified photocathode yielded 61% RB5 dye degradation over 72 h which indicated a highly enhanced performance compared with the irradiated bare graphite (11.74%). Besides, the maximum power density produced was 53.8 mW m^-2 under visible light illumination and 32.5 mW m^-2 in dark conditions. The MPEC reported in this research seems to be a promising system for bioelectricity generation, wastewater treatment in the anodic chamber, and also, dye pollutant degradation in the cathodic chamber.