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Effect of pre-annealing on chemical configuration and heteroatom doping of highly active carbon catalysts for the oxygen reduction reaction.

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Title: Effect of pre-annealing on chemical configuration and heteroatom doping of highly active carbon catalysts for the oxygen reduction reaction.
Authors: Lee, Hae Ri1 (AUTHOR), Han, Seunggyun1 (AUTHOR), Lee, Jong Yoon2 (AUTHOR), Lee, Gwanwon1,3 (AUTHOR), Lee, Sungho3,4 (AUTHOR), Joh, Han-Ik1 (AUTHOR) hijoh@konkuk.ac.kr
Source: Journal of Industrial & Engineering Chemistry. Dec2023, Vol. 128, p542-549. 8p.
Subjects: Platinum group catalysts, Oxygen reduction, Catalysts, Catalytic activity, Nitrogen, Boron isotopes, Carbonyl group, Platinum catalysts
Abstract: [Display omitted] Heteroatom-doped carbon catalysts are promising alternatives to platinum group metal-free catalysts for oxygen reduction reaction (ORR). To enhance the ORR activity of carbon-based catalysts, the break of electroneutrality and number of active sites must be maximized. In this study, an annealing process at a mild temperature was introduced before heteroatom doping to control the content and configuration of the oxygen functional groups on the graphene oxide (GO). Pre-annealing affects the chemical configuration and the porosity of GO such that the epoxy groups are converted into carbonyl groups accompanying the defect formation. Interestingly, The carbonyl-enriched environment allowed ammonia borane, as a dopant with nitrogen and boron atoms, the enhanced doping performance, inducing the formation of higher number of heteroatom doping sites and additional defects in the graphene lattice. The aBNG-150 catalyst demonstrated outstanding ORR activity in both half- and single-cell evaluations because it had the highest heteroatom content and meso/macropores derived from the elimination of oxygen functional groups, which can facilitate ORR catalytic activity and O 2 diffusion pathway. Therefore, we believe that this approach provides an effective route for synthesizing carbon-based catalysts with remarkable ORR performances. [ABSTRACT FROM AUTHOR]
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Database: Engineering Source
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Abstract:[Display omitted] Heteroatom-doped carbon catalysts are promising alternatives to platinum group metal-free catalysts for oxygen reduction reaction (ORR). To enhance the ORR activity of carbon-based catalysts, the break of electroneutrality and number of active sites must be maximized. In this study, an annealing process at a mild temperature was introduced before heteroatom doping to control the content and configuration of the oxygen functional groups on the graphene oxide (GO). Pre-annealing affects the chemical configuration and the porosity of GO such that the epoxy groups are converted into carbonyl groups accompanying the defect formation. Interestingly, The carbonyl-enriched environment allowed ammonia borane, as a dopant with nitrogen and boron atoms, the enhanced doping performance, inducing the formation of higher number of heteroatom doping sites and additional defects in the graphene lattice. The aBNG-150 catalyst demonstrated outstanding ORR activity in both half- and single-cell evaluations because it had the highest heteroatom content and meso/macropores derived from the elimination of oxygen functional groups, which can facilitate ORR catalytic activity and O 2 diffusion pathway. Therefore, we believe that this approach provides an effective route for synthesizing carbon-based catalysts with remarkable ORR performances. [ABSTRACT FROM AUTHOR]
ISSN:1226086X
DOI:10.1016/j.jiec.2023.08.019