Polydopamine anchored localized growth of copper nanoparticles on carbon felt electrode for bioelectrochemical dye degradation

Surface functionalized electrodes facilitate easy electron exchange for the redox reactions in microbial fuel cell (MFC). Synthetic binders used for nanomaterial deposition compromises the reproducibility, stability and obstruct the active catalytic sites. Polydopamine (PDA) coating on electrode provides amine and catechol groups for localization of Cu2+ ions. Higher concentration of Cu2+ facilitated faster growth of copper nanoparticles (CuNPs) using Curcuma longa extract as reducing agent. In-situ growth of CuNP@PDA on carbon felt (CF) reduced the charge transfer resistance and provided redox active species for electron transfers. CuNP@PDA CF cathode resulted in methyl red (MR) degradation in aerated cathode MFC by producing Cu catalyzed reactive oxygen species. MR and O2 compete for electrons at cathode which reduced the overall power output of the MFC. CuNP@PDA CF-MFC was able to produce maximum power density of 15.3 and 6.1 mW/m2 with 10 and 50 mg/L MR respectively as compared to bare CF-MFC which produced 5.5 and 2.7 mW/m2. Dye mineralization could be achieved with CuNP@PDA CF-MFC due to bioelectrochemical advanced oxidation process while bare CF-MFC could only achieve dye decolorization. Such strategy is useful for achieving complete dye removal in a single reactor as compared to conventional dye mineralization process mandating sequential steps.