Synthesis and Performance of a Cathode Catalyst Derived from Bauhinia Accuminata Seed Pods in Single and Stacked Mfc

Abstract

Abstract It becomes important to simultaneously focus on the development of cost-effective electrode materials and catalysts as well as evaluating their performance on stacked systems in order to create scalable bio electrochemical systems for waste water treatment. Platinum group metal free biomass derived cathode catalysts have been observed to improve the microbial fuel cell performance in recent years. But their performance in scalable systems using Natural clay membrane – SS mesh electrode MEA needs to be evaluated for applying to real time systems. In the current work, a catalyst with intrinsic Fe-N-C coordination could be synthesised from the seedpods of biomass Bauhinia Accuminata. The elemental analysis and XPS results confirmed the intrinsic doping of heteroatoms N and P in the catalyst with atomic weight percentages of 4.5 and 3.5, respectively. The deconvolution of N1 and Fe2p spectra confirmed Fe-N-C coordination in the catalyst with pyridinic N and graphitic N content of 17.3% and 34.1%, favouring the ORR activity. The catalyst when coated on SS mesh and used in an MFC system with natural clay membrane - modified SS mesh electrode MEA, the maximum power density was 0.91 W/m3 compared to 0.02 W/m3 in plain SS electrode cell with COD removal efficiency of 93.3%. The study also demonstrated the stepping up of voltage, current and power achieved while stacking such single MFCs in series, parallel, parallel - series and fluidically connected configurations. Parallelly connected system outperformed other systems with a maximum power density of 1.54 W/m3 despite a high OCV of 4.15V attained in series connection. It was also notable that the fluidically connected parallel system achieved better power and current density (0.84W/m3 and 1.97A/m3) than the mixed parallel series circuitry (0.7W/m3 and 0.57A/m3).