Another look at the often ignored role of oxygen functional groups in the oxygen reduction reaction: The promoting effect of carbonyls

• Type: Article in International Scientific Journal
• Date: 2025

Authors

Rui S. Ribeiro (Author) FEUP; Krzysztof Biernacki (Author) Other; Marc Florent (Author) Other; Alexandre L. Magalhães (Author) FCUP; Teresa J. Bandosz (Author) Other; M. Fernando R. Pereira (Author) FEUP

Journal

Title: Carbon

Vol. 242

Initial page: 120449

ISSN: 0008-6223

Publisher: Elsevier

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BiCat4Energy - Electrocatalisadores bifuncionais baseados em materiais de carbono isentos de metais nobres para a produção de energia renovável: melhoramento da tecnologia da Célula de Combustível Unitária Regenerativa.

GreenShip - Electrification of Ships Using Green Fuels and Advanced Technologies

ALiCE - ALiCE - Laboratório Associado em Engenharia Química

Other information

Authenticus ID: P-018-V2Q

DOI: 10.1016/j.carbon.2025.120449

Abstract (EN): Despite the extensive research efforts on carbon-based electrocatalysts, the individual role of oxygen functional groups in the oxygen reduction reaction (ORR) has not been thoroughly clarified yet. A systematic investigation of possible relationships between the performance of progressively reduced graphene oxide (rGO) electrocatalysts in the ORR and their oxygen functional groups was accordingly conducted. rGO electrocatalysts with similar textural properties and crystalline structure, yet with different types and amounts of oxygen functional groups, were obtained by the thermal reduction of graphite oxide at different temperatures in the 400-800 degrees C range. The onset potential of an ORR, in an alkaline medium, became more negative with an increase in the reduction temperature of graphite oxide. Accordingly, the rGO electrocatalyst obtained at 400 degrees C performed best. Molecular modeling, through density functional theory (DFT) calculations, suggested that its superior performance is due to the highest amount of carbonyl groups at the surface of that electrocatalyst. The presence of those groups was shown to increase the chemical reactivity of adjacent carbon atoms and decrease the strength of interactions with O2 in the initial adsorption step, thus reducing the energy barriers for subsequent reduction steps. In fact, a linear dependence was found between an ORR onset potential and the concentration of carbonyls. Therefore, this study points out at carbon atoms adjacent to carbonyls as active centers for oxygen reduction, contributing to the advancement of knowledge on the role of oxygen functional groups in the ORR and to the design of enhanced metal-free carbon electrocatalysts.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 11