Evaluation of a visible light-responsive polyaniline nanofiber-cadmium sulfide quantum dots photocathode for simultaneous hexavalent chromium reduction and electricity generation in photo-microbial fuel cell

Photo-microbial fuel cells (Photo-MFCs) technology have been utilized for cathodic reduction of hexavalent chromium (Cr(VI)) in wastewater and simultaneously electricity generation by using a photocathode. In the present manuscript, polyaniline nanofiber (PANT)-CdS Quantum Dots (QDs) photocathode is prepared via an in-situ method to investigate its performance for reduction of Cr(VI) from wastewaters in Photo-MFC. The structural and optical analyses confirm the enhanced construction and photocatalytic properties of the nanocomposite with high absorption in the visible range. The selected photocathode is also characterized by photo-electrochemical techniques to determine its sensitivity to visible light. In the photoreduction process, the Photo-MFC system equipped with the PANI-CdS QDs photocathode has acquired an outstanding reduction ratio up to 97.4% at a pH value of 2, an initial concentration of 10 mg/L, within illumination time of 8 h and these results follow a pseudo-second-order kinetics with a constant of 0.081 mgL(-1)h(-1), as well. Meanwhile, the Photo-MFC achieves the highest maximum power density of 166.93 mW.m(-2) in the presence of visible light. The present study has successfully confirmed that, Photo-MFC equipped with a PANI-CdS QDs photocathode, can be a promising technology for the reduction of Cr(VI) with an enhanced output power generation simultaneously.