Membrane/Mediator-Free Rechargeable Enzymatic Biofuel Cell Utilizing Graphene/Single-Wall Carbon Nanotube Cogel Electrodes

Abstract

Enzymatic biofuel cells (EBFCs) utilize enzymes to convert chemical energy present in renewable biofuels into electrical energy and have shown much promise in the continuous powering of implantable devices. Currently, however, EBFCs are greatly limited in terms of power and operational stability with a majority of reported improvements requiring the inclusion of potentially toxic and unstable electron transfer mediators or multicompartment systems separated by a semipermeable membrane resulting in complicated setups. We report on the development of a simple, membrane/mediator-free EBFC utilizing novel electrodes of graphene and single-wall carbon nanotube cogel. These cogel electrodes had large surface area (∼ 800 m(2) g(-1)) that enabled high enzyme loading, large porosity for unhindered glucose transport and moderate electrical conductivity (∼ 0.2 S cm(-1)) for efficient charge collection. Glucose oxidase and bilirubin oxidase were physically adsorbed onto these electrodes to form anodes and cathodes, respectively, and the EBFC produced power densities up to 0.19 mW cm(-2) that correlated to 0.65 mW mL(-1) or 140 mW g(-1) of GOX with an open circuit voltage of 0.61 V. Further, the electrodes were rejuvenated by a simple wash and reloading procedure. We postulate these porous and ultrahigh surface area electrodes will be useful for biosensing applications, and will allow reuse of EBFCs.

Multicomponent bionanocomposites based on clay-nanoarchitectures for electrochemical devices

“…In fact, with the addition of 0.1 M glucose, a clear increase (blue line) of the anodic current appears compared to that in PBS without glucose. For the here designed mediator-less cell, this behaviour is correlated to a direct electron transfer (DET) at the interface between the active site (FAD) of the enzyme and the conducting elements of the electrode surface, confirming that a DET mechanism is involved [68][69]. The current increase is predominant at a voltage of 0.35 V, which is higher than the typical FAD/FADH2 standard voltage (i.e., −0.460 V in pH 7.0 at 25.8 °C) probably due to the presence of carbon nanotubes that can influence the electrochemical response [56].…”

“…The polarization curves for the described biofuel cell working at two different pH values are shown in Figure 5E. The polarization curves show the common behaviour of microbial fuel cells (MFCs) and EBCs and it can be divided into three zones: I, II and III as shown in Figure 5E, conventionally called the activation zone, ohmic losses, and the mass transport zone [68][69].…”

“…The decrease of power density compared to the cell working in presence of redox mediator is associated with a slower electron transfer at the enzyme-electrode interface. Nevertheless, the confined GOx in halloysite nanotubes was able to work even in DET mechanism, allowing the use also in a physiological environment [68,70].…”

Challenges and Opportunities of Carbon Nanomaterials for Biofuel Cells and Supercapacitors: Personalized Energy for Futuristic Self-Sustainable Devices

“…Another case involved the use of graphene and a single-walled CNT cogel to develop a membrane/mediator-free BFC as shown in Figure 5D [55]. The carbon-based cogel occupied a large surface area of~800 m 2 g −1 while enabling high enzyme loading, unhindered transport through large porosity, and an electrical conductivity of~0.2 S cm −1 .…”

Wearable Biofuel Cells: A Review

“…Furthermore, eventual depletion of the fuel from the bio‐battery is also a cause of concern. Accordingly, researchers, have attempted to address this issue by developing refuelable 85 and rechargeable 86, 87 bio‐batteries.…”