© 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.

中文翻译：

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碳纳米点作为氧还原反应的电催化剂

© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim 电催化剂在提高氧还原反应 (ORR) 的效率方面发挥着关键作用，因此，科学界一直在努力开发具有以下特性的新型廉价材料表现出低 ORR 过电位的能力，并允许通过 4 电子途径发生反应，从而尽可能接近传统使用的铂。在这种情况下，本文制造了两种不同类型的具有酰胺 (CND-CONH 2 ) 和羧基 (CND-COOH) 表面基团的碳纳米点 (CND)，并显示出在酸性和碱性介质中对 ORR 表现出优异的电催化活性(0.1 MH 2 SO 4 和0.1 M KOH)。CND 表面改性碳丝网印刷电极可以轻松进行电极改性，并能够研究 CND 对 ORR 的电催化活性。与裸/未改性 SPE 相比，CND-COOH 改性 SPE 表现出改善的 ORR 峰值电流和降低的过电位分别为 21.9% 和 26.3%。此外，发现在含氧 0.1 M KOH 中的 424 μg cm -2 CND-COOH 修饰的 SPE 通过近乎最佳的 4 (3.8) 电子 ORR 途径促进 ORR。CND 还表现出出色的长期稳定性和耐受性，在可实现的电流中没有观察到退化，ORR 电流在暴露于 1.5 M 甲醇溶液 100 秒内恢复到基线水平。总之，