Oxygen reduction mechanism on copper in a 0.5 M H2SO4 |
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Authors: | Yonghong Lu Jia Wang Xiangfeng Kong |
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Affiliation: | a Key Laboratory of Marine Chemistry Theory and Technology, Ministry of Education, College of Chemistry and Chemical Engineering, Ocean University of China, 238 Songling Road, Qingdao 266100, Shandong Province, China b State Key Laboratory for Corrosion and Protection of Metals, Shenyang 110016, China |
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Abstract: | The mechanism of the oxygen reduction reaction (ORR) in a naturally aerated stagnant 0.5 M H2SO4 was studied using electrochemical methods. The cathodic polarization curve showed three different regions; electrochemical impedance spectroscopy (EIS) measurement was used accordingly. The EIS data were analyzed, and the mechanism for the ORR was proposed consequently. The three regions include a limiting current density region with the main transfer of 4e− controlled by diffusion (−0.50 V < E < −0.40 V), a combined kinetic-diffusion region (−0.40 V < E < −0.20 V) with an additional 2e− transfer due to the adsorption of the anions, and a hump phenomenon region (−0.20 V < E < −0.05 V), in which the chemical redox between the anodic intermediate and the cathodic intermediate , together with the electrochemical reaction, synergistically results in the acceleration of the ORR. Therefore, a coupled electrochemical/chemical process (the EC mechanism) in the hump phenomenon region was proposed, and a good agreement was found between the experimental and fitted results. The EC mechanism was confirmed by the deaerated experiments. |
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Keywords: | Oxygen reduction Hump phenomenon Chemical redox Copper Electrochemical impedance spectroscopy |
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