Charge-storage process in IrO 2 -SnO 2 mixed-oxide electrodes. Role of coating composition, solution pH and Temperature
| Autor: | Achille De Battisti, Davide Rosestolato, Carlos A. Martínez-Huitle, Sergio Ferro |
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| Rok vydání: | 2014 |
| Předmět: |
Oxide electrodes
Chemistry General Chemical Engineering Double-layer capacitance Analytical chemistry Oxide Ambientale temperature Oxide electrodes charging/discharging process temperature double-layer capacitance Activation energy engineering.material Redox Chemical reaction chemistry.chemical_compound Coating Electrical resistivity and conductivity charging/discharging process Electrochemistry engineering Mixed oxide double-layer capacitance |
| Zdroj: | Electrochimica Acta. 148:85-92 |
| ISSN: | 0013-4686 |
| Popis: | A B S T R A C T The effects of both pH and temperature on the kinetics of redox processes that involve the charging/ discharging of electrocatalytic sites, at dimensionally stable anodes, have been investigated. At first, electrodes based on Ir and Sn oxides, having different molar compositions, were studied by X-ray diffraction in order to characterize the system under investigation, and with the four-probe method to evaluate how the film resistivity varies with the oxide composition. Then, cyclic voltammetric experiments were carried out at different temperatures to estimate the apparent activation energy (Wa) of the charging/discharging process of active sites. The Wa values obtained were rather low (about 0.5 kcal mol � 1 ) and thus realistically not attributable to any chemical reaction. By excluding a role for the various physicochemical parameters that could influence the process, we suggest that the “double injection/double ejection” mechanism is related to a Grotthuss-type movement of protons, which takes its advantage from an electrode-electrolyte interface extending for a few monolayers within the oxide coating. The interface thus represents a relatively rigid and organized structure in which protons can move without any hindrance. |
| Databáze: | OpenAIRE |
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