Tailoring hierarchically porous graphene architecture by carbon nanotube to accelerate extracellular electron transfer of anodic biofilm in microbial fuel cells

摘要

To overcoming their respective shortcomings of graphene and carbon nanotube, a hierarchically porous multi-walled carbon nanotube@reduced graphene oxide (MWCNT@rGO) hybrid is fabricated through a versatile and scalable solvent method, in which the architecture is tailored by inserting MWCNTs as scaffolds into the rGO skeleton. An appropriate amount of inserted 1-D MWCNTs not only effectively prevent the aggregation of rGO sheets but also act as bridges to increase multidirectional connections betweeb 2-D rGO sheets, resulting in a 3-D hierarchically porous structure with large surface area and excellent biocompatibility for rich bacterial biofilm and high electron transfer rate. The MWCNT@rGO(1:2)/biofilm anode delivers a maximum power density of 789 mW m(-2) in Shewanella putrefaciens CN32 microbial fuel cells, which is much higher than that of individual MWCNT and rGO, in particular, 6-folder higher than that of conventional carbon cloth. The great enhancement is ascribed to a synergistic effect of the integrated biofilm and hierarchically' porous structure of MWCNT@rGO(1:2)/biofilm anode, in which the biofilm provides a large amount of bacterial cells to.raise the concentration of local electron shuttles for accelerating the direct electrochemistry on the 3-D hierarchically porous structured anodes. (C) 2016 Elsevier B.V. All rights reserved.