Abstract
Biofuel cell (BFC) electrodes are typically manufactured by combining enzymes that act as catalysts with conductive carbon nanomaterials in a form of enzyme-nanocomposite. However, a little attention has been paid to effects of the carbon nanomaterials' structural properties on the electrochemical performances of the enzyme-nanocomposites. This work aims at studying the effects of surface and bulk properties of carbon nanomaterials with different degrees of graphitization on the electrochemical performances of glucose oxidase (GOx)-nanocomposites produced by immobilizing GOx within a network of carbon nanopaticles. Two types of carbon nanomaterials were used: graphitized mesoporous carbon (GMC) and purified mesoporous carbon (PMC). Graphitization index, surface functional groups, hydrophobic properties, and rate of aggregation were measured for as-received and acid-treated GMC and PMC samples by using Raman spectrometry, X-ray photoelectron spectroscopy (XPS), contact angle measurement, and dynamic light scattering (DLS), respectively. In addition to these physical property characterizations, the enzyme loading and electrochemical performances of the GOx-nanocomposites were studied via elemental analysis and cyclic voltammetry tests, respectively. We also fabricated BFCs using our GOx-nanocomposite materials as the enzyme anodes, and tested their performances by obtaining current-voltage (IV) plots. Our findings suggest that the electrochemical performance of GOx-nanocomposite material is determined by the combined effects of graphitization index, electrical conductivity and surface chemistry of carbon nanomaterials.
Highlights
Self-powered implantable devices such as deep brain neurostimulators, pacemakers, and biosensors for environmental monitoring have enormous potential in medical, agricultural or even military applications (Falk et al, 2012; Katz, 2013)
This work aims to study the effects of the bulk and the surface properties of different carbon nanomaterials on the electrochemical performances of glucose oxidase (GOx)nanocomposite bioanode materials under the Biofuel cell (BFC) operation mode
The Graphitized mesoporous carbons (GMC) sample shows a strong D′ peak at around 2,700 cm−1. These sharp G peak and strong G′ peak shown in the Raman spectrum of the GMC sample indicate that the GMC is consisted of a multilayer of graphene and, it presents a very organized bulk structure
Summary
Self-powered implantable devices such as deep brain neurostimulators, pacemakers, and biosensors for environmental monitoring have enormous potential in medical, agricultural or even military applications (Falk et al, 2012; Katz, 2013). Enzymatic BFCs use (1) enzymes to catalyze both oxidation of organic fuels and reduction of oxidizing agents, and (2) conductive materials (such as carbon nanomaterials) to transmit the electrons between the enzymes’ active sites and the electrodes. Graphitized mesoporous carbons (GMC) and purified mesoporous carbons (PMC) are two types of mesoporous carbon materials with similar chemical composition and morphological properties, but different surface and structural properties. This contrast on the properties of GMC and PMC makes them the ideal carbon nanomaterials for investigating the effects of carbon nanomaterials’ properties on the electrochemical performances of BFCs
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