Binder-free Fe nano oxides decoration for stimulating power generation in microbial fuel cell: Effects on electrode substrates and function mechanism

Nanomaterials are ideal for electrode modification to improve the power output of microbial fuel cells (MFCs). The nanomaterials decoration usually needs a conductive binder which faces the problem of high cost and low conductivity, significantly constraining further application. This study successfully fabricated the binder-free Fe nano oxides modified anodes through the solvothermal method. MFC assembled with carbon cloth/Fe nano oxides (M−CC/Fe) achieved the highest maximum power density (471.6 mW m−2), dramatically higher than that with carbon cloth (M−CC, 150.4 mW m−2), Ni foam/Fe nano oxides (M−NF/Fe, 130.6 mW m−2) and Ni foam (M−NF, 16.5 mW m−2). The electrochemical catalyzing activity, extracellular electron transfer rate, COD removal efficiency and coulombic efficiency were all improved after Fe nano oxides decoration in MFCs. Fe nano oxides enriched exoelectrogens/iron-reducing bacteria like Geobacter and Comamonas and showed a mutual benefit relationship with them. The formation of stable Fe nano oxide cubes significantly enhanced the electroactive biofilm development and alleviated the corrosion of the electrode substrate. The complementary merits of the carbon-based electrode and Fe nano oxides performed better in stimulating power generation in MFCs. These results provided knowledge of in-situ nanomaterials decoration for advanced anodes, providing suggestions for high-performance resource recovery from wastewater.