Three-Dimensional N-Doped Carbon Nanotube/Graphene Composite Aerogel Anode to Develop High-Power Microbial Fuel Cell

Abstract

Optimizing the structure of electrode materials is one of the most effective strategies for designing high-power microbial fuel cells (MFCs). However, electrode materials currently suffer from a series of shortcomings that limit the output of MFCs, such as high intrinsic resistance, poor electrolyte wettability, and low microbial load capacity. Here, a three-dimensional (3D) nitrogen-doped multiwalled carbon nanotube/graphene (N-MWCNT/GA) composite aerogel is synthesized as the anode for MFCs. Comparing nitrogen-doped GA, MWCNT/GA, and N-MWCNT/GA, the macroporous hydrophilic N-MWCNT/GA electrode with an average pore size of 4.24 µm enables high-density loading of the microbes and facilitates extracellular electron transfer with low intrinsic resistance. Consequently, the hydrophilic surface of N-MWCNT can generate high charge mobility, enabling a high-power output performance of the MFC. In consequence, the MFC system based on N-MWCNT/GA anode exhibits a peak power density and output voltage of 2977.8 mW m−2 and 0.654 V, which are 1.83 times and 16.3% higher than those obtained with MWCNT/GA, respectively. These results demonstrate that 3D N-MWCNT/GA anodes can be developed for high-power MFCs in different environments by optimizing their chemical and microstructures.