Improving the performance of microbial fuel cell stacks via capacitive-hydrogel bioanodes.

We constructed a capacitive bioanode PPy/EABs@Mag-CLF/SA for circumventing the bioelectrochemical reaction shift during voltage reversal of series-stacked MFC. Sodium alginate hydrogel (SA) was made as the binder, in which the conducting polymer polypyrrole (PPy) was doped. Biomagnetic carbonized loofah particles (EABs@Mag-CLF) cultured in a pulsating fluidized bed were encapsulated by hydrogel as the anode biocatalyst. The pseudocapacitive material PPy combined with the biofilm capacitance attached to 3D biochar particles together constructed the biocapacitor anode with an energy storage function. The result showed that the power density of PPy100/EABs@Mag-CLF100/SA (71.88 W/m3) was 1.87 times more than PPy100/EABs@Mag-CLF50/SA. In the charge/discharge test (C60/D60), the stored charge Q s of PPy100/EABs@Mag-CLF100/SA (460.97 C/m2) was 3.74 times greater than that of PPy20/EABs@Mag-CLF100/SA. Stacked MFCs equipped with PPy100/EABs@Mag-CLF100/SA anodes had a smaller threshold resistance (R threshold) and recovered their performance even after a voltage reversal. This can provide an ideal energy solution for intermittently operating microelectronic devices. [Display omitted] • The bio-loading step was added to the anode preparation process. • Intermittent pulsating fluidized beds were used to culture EABs@Mag-CLF. • Hydrogel capacitive bioanodes were used to buffer voltage reversal. • The charge/discharge capability of MFC was enhanced by PPy/EABs@Mag-CLF/SA. • Traditional 3D structures were replaced by carbonized N-doped biochar particles. [ABSTRACT FROM AUTHOR]