The Role of Nanostructure in the Electrochemical Oxidation of Model-Carbon Materials in Acidic Environments

Abstract

Carbon is ubiquitous in electrochemical energy devices and may exist in varied forms ranging from crystalline or amorphous to novel nanostructures based on a few sheets of graphene. The electrochemical oxidation of carbon results in the performance degradation of the electrochemical device. A study on the structure-reactivity relationship of the electrochemical oxidation of graphene-based carbon materials ͑carbon black, carbon onions, multiwalled nanotubes, and exfoliated graphite platelets͒ is presented. High resolution transmission electron microscopy, X-ray diffraction, elemental analysis, and N 2 adsorption were used to characterize the materials tested. Both liquid half-cell tests and proton exchange membrane fuel cell tests with inline carbon dioxide analysis were used to study the electrochemical behavior. The electrochemical oxidation of 10 seemingly disparate carbon materials was separated into two distinct mechanisms. Both mechanisms approach an 80% current efficiency for carbon dioxide formation. Iron and sulfur impurities are insignificant controlling factors. The difference between the two mechanisms is tentatively attributed to the degree of interlayer interaction between graphene sheets.

Novel Graphitised Carbonaceous Materials for Use as a Highly Corrosion‐Tolerant Catalyst Support in Polymer Electrolyte Fuel Cells

“…At a potential of 0.55-0.60 V (vs. RHE) in the CVs of CB (Figure 8c), there was a redox couple, which was attributed to the redox of quinone/hydroquinone [27]. Gallagher et al [28] also showed the similar CVs, which have redox peaks around 0.6 V, in the case of Vulcan XC72. On the other hand, the CVs of CNSs (Figure 8b) showed no clear redox peaks or an increase in overall capacitance.…”

Nanostructured activated carbons from natural precursors for electrical double layer capacitors

“…However, the post heat-treating in air atmosphere increased the wettability of carbon with the electrolyte of KOH aqueous solution, and the capacitances of electrodes were also enhanced. Furthermore, defects on surface of carbon were proposed to interact with the solvation shells of the ions, decreasing the average carbon surface-ion separation distance, and thereby increasing specific capacitance [20,106]. In Ref.…”

Enhanced electro-oxidation resistance of carbon electrodes induced by phosphorus surface groups

“…Various studies comparing the electro-oxidation behavior of different carbon materials have been published [16][17][18][19][20]. However, little is unambiguously known regarding the mechanism of electrochemical oxidation [21][22][23][24][25].…”

“…As a consequence, few strategies to improve the carbon electro-oxidation resistance have been proposed. Most approaches involve a decrease in the amount of active sites by controlling the carbon morphology and structure [15][16][17][18][19][20]26,27], and/or by reducing the surface area [19,28].…”