Insights into electrochemical behavior and anodic oxidation processing of graphite matrix in aqueous solutions of sodium nitrate

The electrochemical oxidation of graphite matrix from the simulative fuel elements for high-temperature gas-cooled reactor was investigated experimentally using NaNO 3 solution as an electrolyte. The intercalation and oxidation reactions of graphite were investigated by means of cyclic voltammetry....

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Bibliographic Details
Published in:Journal of applied electrochemistry 2016-12, Vol.46 (12), p.1163-1176
Main Authors: Zhang, Gengyu, Wen, Mingfen, Wang, Shuwei, Chen, Jing, Wang, Jianchen
Format: Article
Language:English
Subjects:
Anodizing
Aqueous solutions
Carbonyls
Chemistry
Chemistry and Materials Science
Cracks
Crystal defects
Destruction
Disintegration
Electrochemical analysis
Electrochemical oxidation
Electrochemical Processes
Electrochemistry
Electrolysis
Gas evolution
Graphite
High temperature gas cooled reactors
Industrial Chemistry/Chemical Engineering
Intercalation
Nuclear fuel elements
Nuclear fuels
Oxidation
Physical Chemistry
Research Article
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Summary:The electrochemical oxidation of graphite matrix from the simulative fuel elements for high-temperature gas-cooled reactor was investigated experimentally using NaNO 3 solution as an electrolyte. The intercalation and oxidation reactions of graphite were investigated by means of cyclic voltammetry. In addition, the morphological changes of the graphite anodes at predetermined intervals of time during the electro-oxidation process were examined by scanning electron microscopy. The structural transformation of graphite was systematically characterized by different methods. Results showed that the electro-oxidation process induced oxygen-containing groups (i.e., hydroxyl, epoxide, carbonyl/ketone, and carboxyl groups) into the graphite backbone. Electrolytic graphite oxide presented a heterogeneous, indeterminate, and disordered system composed of crystalline and amorphous phases. The structure and microstructure of nuclear graphite, particularly its cracks and defects, primarily determined its destruction pathway during the electrolytic process. The mechanism of graphite lattice destruction could be attributed to the complicated interplay of water electrolysis, anionic intercalation, and gas evolution. The mechanical force caused by gas eruptions among the graphite lattice is the most important and essential factor favoring disintegration. Graphical Abstract
ISSN:0021-891X
1572-8838
DOI:10.1007/s10800-016-0999-0