Enhancement of interfacial bioelectrocatalysis in Shewanella microbial fuel cells by a hierarchical porous carbon–silica composite derived from distiller's grains

Abstract

The microbial fuel cell (MFC) is an attractive green energy source since it can use wastewater and/or organic wastes as fuels to generate electricity. A cost-effective anode material with superior bioelectrocatalysis activity is critical to MFC. In this study, a honeycomb-like hierarchical porous carbon–silica (PC/Si) composite with macropores (2–15 μm) and mesopores (3–4 nm) was derived from distiller's grains via a simple carbonization procedure and used as an anode in a Shewanella putrefaciens CN32 (S. putrefaciens CN32) fuel cell for the first time. The obtained three dimensional scaffold structure with meso pores on the wall provides not only a large surface for bacteria adhesion, but also more active sites for flavin mediated interfacial electron transfer. It is interesting that the siliceous crusts of this PC/Si composite greatly promote the bacteria adhesion as well as a uniform biofilm formation. Accordingly, the PC/Si anode delivers a maximum power density of 580.7 mW m⁻² in S. putrefaciens CN32 MFC, which is 4.5-fold higher than that of the conventional carbon cloth anode. Considering the synthesis process of this biomass based carbon material is facile, this PC/Si anode could be very promising when applied for high performance, large scale MFC.