Neutron Imaging and Electrochemical Characterization of a Glucose Oxidase-Based Enzymatic Electrochemical Cell

Abstract

Enzymatic electrochemical cells (EECs) are a candidate for providing “green” solutions to a plethora of low-power, long-lifetime applications. A prototype three-electrode biobattery configuration of an EEC has been designed and fabricated for neutron imaging and electrochemical testing to characterize cell performance. The working electrode (WE) was catalyzed by a polymer ink-based biocatalyst with carbon felt (CF) serving as the supporting material. Results of both ex situ and in operando neutron imaging are presented as methods for relating fuel distribution, the distribution of the enzymes, and cell electrochemical performance. Neutron radiography (NR) was also performed on fuel solutions of varied concentrations to calibrate fuel solution thickness and allow for transient mapping of the fuel distribution. The calibration data proved useful in mapping the thickness of fuel solution during transient radiography. When refueled after electrochemical testing and neutron imaging, the cell surpassed its original performance, indicating that exposure to the neutron beam had not detrimentally affected enzyme activity. In operando mapping of the fuel solution suggests that increased wetting of the catalyst region increases cell performance. The relation of this performance increase to active region wetting is further supported by fuel distributions observed via the ex situ tomography. While useful in mapping aggregate solution wetting, the calibration data did not support reliable mapping of detailed glucose concentration in the WE. The results presented further demonstrate potential for the application of neutron imaging for the study of EECs, particularly with respect to mapping the distribution of aqueous fuel solutions.