Abstract
This paper reports on a miniaturized microbial fuel cell with a microfluidic flow-through configuration: a porous anolyte chamber is formed by filling a microfluidic chamber with three-dimensional graphene foam as anode, allowing nutritional medium to flow through the chamber to intimately interact with the colonized microbes on the scaffolds of the anode. No nutritional media flow over the anode. This allows sustaining high levels of nutrient utilization, minimizing consumption of nutritional substrates, and reducing response time of electricity generation owing to fast mass transport through pressure-driven flow and rapid diffusion of nutrients within the anode. The device provides a volume power density of 745 μW/cm3 and a surface power density of 89.4 μW/cm2 using Shewanella oneidensis as a model biocatalyst without any optimization of bacterial culture. The medium consumption and the response time of the flow-through device are reduced by 16.4 times and 4.2 times, respectively, compared to the non-flow-through counterpart with its freeway space volume six times the volume of graphene foam anode. The graphene foam enabled microfluidic flow-through approach will allow efficient microbial conversion of carbon-containing bioconvertible substrates to electricity with smaller space, less medium consumption, and shorter start-up time.
Highlights
This paper reports on a miniaturized microbial fuel cell with a microfluidic flow-through configuration: a porous anolyte chamber is formed by filling a microfluidic chamber with three-dimensional graphene foam as anode, allowing nutritional medium to flow through the chamber to intimately interact with the colonized microbes on the scaffolds of the anode
Due to the large surface area-to-volume ratio, many micro/nanomaterials have been developed as anode materials of μMFCs to promote bacterial attachment and colonization, and electrochemical catalytic activity of anodes, such as carbon nanotubes (CNTs)[23,28,43,44], graphene[45], graphene-based nanocomposites[27,29,30], poly(3,4-ethylenedioxy-thiophene) (PEDOT)[31,32,46], and PEDOT-based nanocomposites[34,35,36,37,38,39,40,41,42]
Most existing μMFCs employ a similar device structure where carbon-containing organic substrate solutions flow over the surface of a planar metal anode or micro/nanomaterials-based anode emplaced on the bottom of anolyte chamber or attached to a proton exchange membrane (PEM)
Summary
Most existing μMFCs employ a similar device structure where carbon-containing organic substrate solutions flow over the surface of a planar metal anode (e.g. gold) or micro/nanomaterials-based anode emplaced on the bottom of anolyte chamber or attached to a proton exchange membrane (PEM). A microfluidic vanadium redox fuel cell was reported utilizing carbon paper based electrodes to enable cross-flow of the fuel and oxidant solutions through the electrodes into an exit channel[48] This remarkable architecture increased the active area of vanadium redox reactions and enhanced rates of mass transport inside the anode. We report an integrated microfluidic FT μMFC using 3D graphene foam (GF) as anode able to minimize bioconvertible substrate consumption, sustain high levels of nutrient utilization, and reduce response time of electricity generation (Fig. 1). A field-emission scanning electron microscope (SEM; Quanta-250; FEI, Hillsboro, OR) was used
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