Electrocatalysis of Oxygen Reduction in Polymer Electrolyte Fuel Cells: A Brief History and a Critical Examination of Present Theory and Diagnostics

Gottesfeld, S.

doi:10.1002/9780470463772.ch1

Cited by 40 publications

(44 citation statements)

References 19 publications

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“…The latter is caused by the growth of oxygen functional groups (OFGs) between the graphitic layers, which caused an expansion of the C-C interplanar spacing from 0.34 to 0.84 nm, and therefore, a weakening of the respective chemical bonds of graphite [8,13]. On the other hand, the X-ray patterns and interplanar spacing of doped-rGO materials (N-rGO, SN-rGO and SN 2 -rGO) and carbon Vulcan are quite similar (Table 1), which suggests two important issues derived from the effective reduction step: (i) OFGs in the interstitial graphitic spaces were successfully removed, and (ii) the C-C lattice of graphite was effectively restored [1,8,9,14]. Noticeably, N-rGO develops a small but visible diffraction peak close to 12 • that is characteristic of GO, which suggests a partial reduction of GO when caffeine is used as a reducing agent.…”

Section: Introductionmentioning

confidence: 94%

“…They have the potential to provide environmentally friendly energy conversion with a high efficiency and power density [1,2]. One of the main research areas for polymer electrolyte membrane (PEM) FCs involves the oxygen reduction reaction (ORR) in acidic and alkaline media at the cathode of these devices.…”

Section: Introductionmentioning

confidence: 99%

“…One of the main research areas for polymer electrolyte membrane (PEM) FCs involves the oxygen reduction reaction (ORR) in acidic and alkaline media at the cathode of these devices. The great importance of this issue is related to the sluggish ORR kinetic that is responsible for more than half of the overall cell voltage loss during the FC's working operation [1,2]. Therefore, developing low-cost electrocatalysts with a high performance toward the ORR is of paramount importance to support the industrial operation of FCs [3,4].…”

Section: Introductionmentioning

confidence: 99%

“…Therefore, developing low-cost electrocatalysts with a high performance toward the ORR is of paramount importance to support the industrial operation of FCs [3,4]. In this context, graphene-based materials appear as a promising means to fulfil the previously mentioned requirements [1].…”

Section: Introductionmentioning

confidence: 99%

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S- and N-Doped Graphene Nanomaterials for the Oxygen Reduction Reaction

et al. 2017

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In the current work, heteroatom-doped graphene materials containing different atomic ratios of nitrogen and sulphur were employed as electrocatalysts for the oxygen reduction reaction (ORR) in acidic and alkaline media. To this end, the hydrothermal route and different chemical reducing agents were employed to synthesize the catalytic materials. The physicochemical characterization of the catalysts was performed by several techniques, such as X-ray diffraction, Raman spectroscopy and elemental analysis; meanwhile, the electrochemical performance of the materials toward the ORR was analyzed by linear sweep voltammetry (LSV), rotating disk electrode (RDE) and rotating ring-disk electrode (RRDE) techniques. The main results indicate that the ORR using heteroatom-doped graphene is a direct four-electron pathway, for which the catalytic activity is higher in alkaline than in acidic media. Indeed, a change of the reaction mechanism was observed with the insertion of N into the graphenic network, by the rate determining step changes from the first electrochemical step (formation of adsorbed OOH) on glassy carbon to the removal of adsorbed O (O ad ) from the N-graphene surface. Moreover, the addition of sulphur atoms into the N-graphene structure increases the catalytic activity toward the ORR, as the desorption of O ad is accelerated.

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Section: Introductionmentioning

confidence: 94%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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S- and N-Doped Graphene Nanomaterials for the Oxygen Reduction Reaction

et al. 2017

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“…Além disso, desafios econômicos tambem são um entrave à inserção comercial de tais dispositivos. Nesse sentido, pesquisas tem se dedicado a diminuir a carga de metais nobres nos MEAs, bem em otimizar a utilização dos metais eletrocataliticos [29,30] .…”

Section: Objetivos Específicosunclassified