Sulfonated graphene oxide and titanium dioxide coated with nanostructured polyaniline nanocomposites as an efficient cathode catalyst in microbial fuel cells.

In this study, sulfonated graphene oxide (SGO) was synthesized as potential conducting matrix to improve the properties of catalyst for single chamber microbial fuel cells (SC-MFCs). Here, TiO2 and Polyaniline (PAni) nanoparticles were anchored over SGO and the resulting SGO-TiO2-PAni nanocomposites were used as a potential cathode catalyst in MFCs. We have also examined the performance of SGO-TiO2-PAni compared to GO-TiO2-PAni and TiO2-PAni catalyst. The structural and morphological analyses were examined using a variety of characterization techniques. TiO2 nanoparticles bridged PAni and SGO through hydrogen bonding/electrostatic interaction and improved the thermal stability of SGO-TiO2-PAni catalyst. The electrochemical characterizations of these nanocatalysts suggest that the SGO-TiO2-PAni showed higher reduction current value (-0.46 mA), enhanced stability, and lower internal resistance (46.2 Ω) in comparison to GO-TiO2-PAni and TiO2-PAni towards oxygen reduction reactions (ORR). Consequently, MFC using SGO-TiO2-PAni demonstrated a maximum power density of 904.18 mWm-2 than that of GO-TiO2-PAni (734.12 mWm-2), TiO2-PAni (561.5 mWm-2) and Pt/C (483.5 mWm-2). The enhanced catalytic activity of SGO-TiO2-PAni catalyst was ascribed to the high electronic conductivity and long-term permanence of the nanocomposite. These superior electrochemical results suggested that the SGO-TiO2-PAni catalyst could be applied as a potential alternative to the commercial Pt/C cathode catalyst for the application of MFCs.