High‐Power Microbial Fuel Cells Based on a Carbon–Carbon Composite Air Cathode

Abstract

The increasing demand for water and energy has become a critical issue and challenge worldwide. Notably, water and energy are tightly linked and there is a strong nexus between them. On the one hand, wastewater treatment consumes around 3% of the electric power generated in the United States. [1] On the other hand, wastewater is also considered as an excellent source of clean water and energy, and the potential energy in Microbial fuel cells (MFCs) can convert organics in wastewater directly to electricity, and improving oxygen reduction reaction (ORR) performance is critical to their development and future applications. Electrocatalytic ORR performance is determined by the intrinsic activity and accessible amounts of active sites. A surface nitrogen-enriched carbon coaxial nanocable (NCCN) is applied as an ORR electrocatalyst and combined with activated carbon (AC) with 80 wt% addition as a carbon-carbon composite air cathode in MFCs. The fully exposed nitrogen active sites of NCCN contribute to the enhanced ORR activity, while the graphitized core affords a rapid pathway for electron transportation. AC serves as a spacer to construct a porous framework with interconnected ion diffusion channels. This cathode thus exhibits a maximum power density of 2090 mW m -2 , 120% higher than commercial Pt/C electrocatalysts, and also 6% higher than the pure NCCN, indicating a synergistic effect between NCCN and AC. A high-performance NCCN-AC air cathode with a great promise for future MFC applications is reported and an effective strategy to bridge the electrocatalytic performance from nanomaterials to practical devices is presented.

Bio-electrochemical frameworks governing microbial fuel cell performance: technical bottlenecks and proposed solutions

“… 165 While the atmospheric oxygen can be used directly by using an air cathode, contact difficulties in the cathode-air surface and the necessity for expensive catalysts are the disadvantages of oxygen utilization. 166 The development of low-cost, high-performance nanocatalysts for the intrinsically slow oxygen reduction process (ORR) is a major roadblock in the commercialization of fuel cells for energy conversion. Recently, a lot of research has been directed towards developing Pd-based nanocatalysts with improved stability to use as Pt alternatives.…”

Understanding Synthesis–Structure–Performance Correlations of Nanoarchitectured Activated Carbons for Electrochemical Applications and Carbon Capture

“…The all-carbon composite air cathodes demonstrated a power density of 2090 mW m -2 , 120% greater than that of Pt/C (Figure 25b,c). [477] Gao et al combined activated carbons, carbon nanotubes, and reduced graphene oxide into ultrathick (10 layers), all-carbon monolithic electrodes by 3D printing, which displayed a large areal/ volumetric capacitance of 4.56 F cm -2 /10.28 F cm -3 as well as high energy densities of 0.63 mWh cm -2 /1.43 mWh cm -3 in the symmetric supercapacitor devices (Figure 25a). [478] Aeby et al invented complete 3D-printed supercapacitors of 25.6 F g -1 at 1.2 V. The substrates, current collectors, electrodes, electrolytes, and final integrated devices were all constructed by direct-ink-writing technology.…”

Preparation and Application of Fe-N Co-Doped GNR@CNT Cathode Oxygen Reduction Reaction Catalyst in Microbial Fuel Cells

“…Several factors affect MFC performance, including anode materials [4][5][6], MFC configurations [7][8][9], cathode catalysts [10][11][12], and electroactive bacteria [13,14]. Among them, the high overpotential loss and price of ORR catalysts play an important role in limiting the power generation capacity.…”