Carbon Nanodots as Electrocatalysts towards the Oxygen Reduction Reaction

Martínez-Periñán, E, Bravo, I, Rowley-Neale, SJ, Lorenzo, E and Banks, CE (2018) Carbon Nanodots as Electrocatalysts towards the Oxygen Reduction Reaction. Electroanalysis, 30 (3). pp. 436-444. ISSN 1040-0397

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Abstract

© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim Electrocatalysts perform a key role in increasing efficiency of the oxygen reduction reaction (ORR) and as a result, efforts have been made by the scientific community to develop novel and cheap materials that have the capability to exhibit low ORR overpotentials and allow the reaction to occur via a 4 electron pathway, thereby mimicking as close as possible to traditionally utilised platinum. In that context, two different types of carbon nanodots (CNDs) with amide (CND-CONH 2 ) and carboxylic (CND-COOH) surface groups, have herein been fabricated and shown to exhibit excellent electrocatalytic activity towards the ORR in acid and basic media (0.1 M H 2 SO 4 and 0.1 M KOH). CND surface modified carbon screen-printed electrodes allow for a facile electrode modification and enabling the study of the CNDs electrocatalytic activity towards the ORR. CND-COOH modified SPEs are found to exhibit improved ORR peak current and reduced overpotential by 21.9 % and 26.3 %, respectively compared to bare/unmodified SPEs. Additionally, 424 μg cm −2 CND-COOH modified SPEs in oxygenated 0.1 M KOH are found to facilitate the ORR via a near optimal 4 (3.8) electron ORR pathway. The CNDs also exhibited excellent long-term stability and tolerance with no degradation being observed in the achievable current with the ORR current returning to the baseline level within 100 seconds of exposure to a 1.5 M solution of methanol. In summary, the CND-COOH could be utilised as a cathodic electrode for PEMFCs offering greater stability than a commercial Pt electrode.