Oxygen Reduction Reaction in a Droplet on Graphite: Direct Evidence that the Edge Is More Active than the Basal Plane |
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| Authors: | Anli Shen Yuqin Zou Prof. Qiang Wang Prof. Robert A. W. Dryfe Prof. Xiaobing Huang Shuo Dou Prof. Liming Dai Prof. Shuangyin Wang |
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| Affiliation: | 1. State Key Laboratory of Chem/Bio‐Sensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Yuelushan, Changsha, Hunan, 410082 (P.R.?China);2. School of Chemistry, The University of Manchester, Manchester, M13?9PL (UK);3. Department of Applied Chemistry, Nanjing Tech University, Nanjing, 211816 (China);4. College of Chemistry and Chemical Engineering, Hunan University of Arts and Science, Changde, Hunan Province (P.R.?China);5. Department of Macromolecular Science and Engineering, Case Western Reserve University, Cleveland, OH?44106 (USA) |
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| Abstract: | Carbon‐based metal‐free electrocatalysts for the oxygen reduction reaction (ORR) in alkaline medium have been extensively investigated with the aim of replacing the commercially available, but precious platinum‐based catalysts. For the proper design of carbon‐based metal‐free electrocatalysts for the ORR, it would be interesting to identify the active sites of the electrocatalyst. The ORR was now studied with an air‐saturated electrolyte solution droplet (diameter ca. 15 μm), which was deposited at a specified position either on the edge or on the basal plane of highly oriented pyrolytic graphite. Electrochemical measurements suggest that the edge carbon atoms are more active than the basal‐plane ones for the ORR. This provides a direct way to identify the active sites of carbon materials for the ORR. Ball‐milled graphite and carbon nanotubes with more exposed edges were also prepared and showed significantly enhanced ORR activity. DFT calculations elucidated the mechanism by which the charged edge carbon atoms result in the higher ORR activity. |
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| Keywords: | droplets electrochemistry fuel cell graphite oxygen reduction reaction |
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