Harvesting energy from living biological environment, such as physiological fluid of human body based on bioelectrochemical reactions has attracted significant attention in the scientific community in the recent decades because of their potential applications in biomedical electronic devices. Here, we describe the construction and characterization of a simple, mediator-free glucose powered enzymatic biofuel cell (EBFC) that employ all biocompatible materials including two-dimensional meso-porous reduced graphene oxide (rGO) as a novel host electrode. This cell uses glucose and molecular oxygen to provide fuel for power generation and consist of two bioelectrodes modified by immobilized enzymes, reduced graphene oxide–glucose oxidase (GOx/rGO) as bioanode and reduced graphene oxide–laccase (Lac/rGO) as biocathode. The enzymes catalyze the oxidation of glucose at the anode by glucose oxidase and the reduction of molecular oxygen at the cathode via laccase. Glucose oxidase and laccase enzymes were non-covalently bonded with the surface of reduced graphene oxide electrodes. The surface morphology, microstructure, and electrochemical properties of rGO, GOx/rGO bio-anode and Lac/rGO bio-cathode have been investigated by N2-sorption, X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), electrochemical impedance spectroscopy (EIS), Raman, FT-IR, UV–vis, and cyclic voltammetry (CV). FT-IR and UV–vis spectroscopies showed that GOx immobilized on rGO matrix remained in its native structure. Direct electrochemistry and electrocatalytic properties of the GOx/rGO and Lac/rGO nanocomposites were investigated and the results showed that the presence of meso-porous rGO greatly enhance the electrochemical response of GOx. The heterogeneous electron transfer rate constant (ks) was estimated to be 4.85 s-1. The fabricated EBFCs delivers a power density up to 7 nw cm-2 with an open circuit voltage of 0.04 V and remains stable for 14 days with power output (9.0 nw cm-2 ) under the physiological conditions (pH 7.4).

Energy harvesting from enzymatic glucose biofuel cell utilizing meso-porous nanostructured reduced graphene oxide electrodes

ACS Fall 2021

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