The novel advancements of nanomaterials in biofuel cells with a focus on electrodes' applications

Abstract

Biofuel cells (BFCs) convert biochemical energy into electrical energy by virtue of the biocatalyst component. They incorporate bio-catalysts composed of microorganisms and enzymes. BFCs are considered among the novel technologies for the production of potable water/electricity and self-powered biosensors simultaneously. However, BFCs, still suffer from various drawbacks, namely, the short lifetime, difficulty in optimizing the optimum operating conditions (substrate concentration and pH), and designing electrodes of sufficient surface area, hence, leading to low power densities and reduced columbic efficiencies. The utilization of nanomaterials in the bioelectrode construction of BFCs has been proposed and demonstrated promising improvement in performance, including electron transfer, thermal and mechanical stability, and conversion efficiency. The use of nanomaterials in bio-electrodes provided large active surface areas between enzymes/electrodes, thus, improving electron kinetics. Carbon-based nanostructures in particular, i.e., carbon-based nanomaterials such as graphene/fullerenes/carbon nanotubes (CNTs)/carbon nanofibers (CNFs), conducting polymers/composites, and metallic nanoparticles/oxides have been extensively investigated. These studies highlighted the progress made in the use of nanomaterials/enzymatic immobilizations for improving the performances of electrodes. Challenges and opportunities related to the stability and durability of BFCs for long-term applications have been discussed for future development directions. Furthermore, recommendations on novel designs of nanomaterials possessing good electrical properties, optimized porous matrix, and ease of separation in nanomaterials/enzymes systems have been discussed for green energy production.