Understanding the role of glucose oxidase on carbon felt as electrodes in biocapacitor studies

Abstract

In this work, we have reported glucose oxidase incorporated carbon felt bioelectrodes (GOx/CFE) as biocapacitors for energy storage. Glucose oxidase (GOx) was incorporated into a carbon felt electrode (CFE) and the electrode was characterized using X-ray diffraction, scanning electron microscope and Fourier transform infrared spectroscopy. As a result, it was found that GOx was successfully incorporated into a bare CFE and enhances the specific capacitance of the electrode and it was stable up to 500 charge–discharge cycles. Consequently, it was observed that GOx/CFE exhibits enhanced energy storage capacitance compared to that of pristine carbon felt. The capacitance of GOx/CFE is found to be \(4.21\hbox { mF cm}^{-2}\,(23\hbox { F g}^{-1})\) while the bare CFE shows \(3.68\hbox { mF cm}^{-2}\) in a phosphate buffer solution (\(\hbox {pH}=7.0\)). Albeit the capacitance values are small compared to conventional supercapacitors, the utility of these biocapacitors is expected to have a significant impact on glucose monitoring. Columbic efficiency obtained with the GOx/CFE matrix is 89%, and the electrode is stable up to 225 cycles with 100% retention of capacitance. After 225 cycles, the electrode loses the capacitance up to 12% retaining the capacitance of 88% up to 500 cycles. Cyclic voltammetric studies revealed that GOx/CFE is capable of energy storage with a \(200\,\upmu \hbox {A}\) higher capacitive loop than the bare CFE at a scan rate of \(10\hbox { mV s}^{-1}\). Electrochemical impedance analysis measurements also confirmed that GOx/CFE possess minimum resistivity. Moreover, it is very eco-friendly due to which unwanted pollution can be avoided. From the proposed matrix, it is believed that a green, eco-friendly, clean, renewable material for energy storage could be realized.