RRDE and Voltammetric Study of ORR on Pyrolyzed Fe/Polyaniline Catalyst. On the Origins of Variable Tafel Slopes

Chlistunoff, Jerzy

doi:10.1021/jp108350t

Cited by 124 publications

(150 citation statements)

References 73 publications

(153 reference statements)

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“…LSV analysis is another crucial method that describes the ORR activity of synthesized nanocomposites using a rotating-disk electrode (RDE) or rotating ring-disk electrode (RRDE). 45,[111][112][113] Similar to CV measurements, the LSV analysis is also performed in an O 2 -saturated 0.1 M KOH solution at different rotation rates under room temperature. The electrolytic bath includes three electrodes: a RDE or RRDE quantitatively coated with the catalyst under investigation, an Ag|AgCl/KCl (saturated) reference electrode and a Pt wire as a counter electrode.…”

Section: Electrocatalytic Orr Characterizationmentioning

confidence: 99%

Graphene-based transition metal oxide nanocomposites for the oxygen reduction reaction

et al. 2015

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The development of low cost, durable and efficient nanocatalysts to substitute expensive and rare noble metals (e.g. Pt, Au and Pd) in overcoming the sluggish kinetic process of the oxygen reduction reaction (ORR) is essential to satisfy the demand for sustainable energy conversion and storage in the future. Graphene based transition metal oxide nanocomposites have extensively been proven to be a type of promising highly efficient and economic nanocatalyst for optimizing the ORR to solve the world-wide energy crisis. Synthesized nanocomposites exhibit synergetic advantages and avoid the respective disadvantages.In this feature article, we concentrate on the recent leading works of different categories of introduced transition metal oxides on graphene: from the commonly-used classes (FeO x , MnO x , and CoO x ) to some rare and heat-studied issues (TiO x , NiCoO x and Co-MnO x ). Moreover, the morphologies of the supported oxides on graphene with various dimensional nanostructures, such as one dimensional nanocrystals, two dimensional nanosheets/nanoplates and some special multidimensional frameworks are further reviewed.The strategies used to synthesize and characterize these well-designed nanocomposites and their superior properties for the ORR compared to the traditional catalysts are carefully summarized. This work aims to highlight the meaning of the multiphase establishment of graphene-based transition metal oxide nanocomposites and its structural-dependent ORR performance and mechanisms.

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Section: Electrocatalytic Orr Characterizationmentioning

confidence: 99%

Graphene-based transition metal oxide nanocomposites for the oxygen reduction reaction

et al. 2015

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“…6,46 However, there are also distinct differences between the imidazole ligated iron tetraphenyl porphyrins and the pyrolyzed Fe/N/C catalysts. These differences will be discussed in the next section.…”

Section: ■ Oxygen Reduction Catalysismentioning

confidence: 99%

Effects of Axial Coordination of the Metal Center on the Activity of Iron Tetraphenylporphyrin as a Nonprecious Catalyst for Oxygen Reduction

Chlistunoff

Sansiñena

2014

J. Phys. Chem. C

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Effects of axial coordination of the metal center on oxygen reduction catalyzed by iron tetraphenylporphyrin have been studied using spectroelectrochemical and rotating ring disk electrode techniques. Among numerous ligands studied, the strongest complexation of the metal center was observed for imidazole and some substituted imidazole ligands. Around 300 mV positive shift of the oxygen reduction potential in 0.5 M H2SO4 was observed when the catalyst support (high surface area carbon Vulcan XC72) was impregnated with polyvinylimidazole. A smaller 200 mV shift of the reduction potential was recorded when graphene modified with 1-(3-aminopropyl)imidazole was used as the catalyst support instead of Vulcan. In both cases, the catalyst selectivity for four-electron reduction was also substantially improved. The effects of iron complexation on oxygen reduction kinetics and mechanism result from both a positive shift of the potential of the first porphyrin reduction and an increase of the electron density on the iron center through the so-called “push effect”. The observed phenomena are discussed in relation to heat-treated Fe/N/C catalysts for oxygen reduction.

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“…[12,13,39,40] For instance, in Figure 4, we show rotating ring disc electrode (RRDE)r esults for catalyst B in sulfuric acid electrolyte as af unctiono fc atalyst loading. It is seen that thinner catalystl ayers resulti ni ncreasedH 2 O 2 percentages detected in the ring, at less positive potentials.…”

Section: Ir-free Polarisationresponse Of Pefcs: Evidence For Twon Ernmentioning

confidence: 99%

“…RRDE)o bserved performances into powero utput in practical devices; (3) dealing with degradation of these catalysts under operational conditions that limit their ultimate lifetime. There has been progress in addressing the oxygen reduction activity of carbon catalysts; [6,[12][13][14][15][16][17][18][19] however,t here is ag ap in understanding the activity of the carbon catalystc athodes, in part due to issues in appropriately determining ORR kinetics andm ass transport overpotential under fuel cell conditions.…”

Section: Introductionmentioning

confidence: 99%

Mechanistic Insights into the Oxygen Reduction Reaction on Metal–N–C Electrocatalysts under Fuel Cell Conditions

et al. 2016

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Three different transition metal‐C‐N catalysts are tested under a range of fuel cell conditions. It is found that common features of the polarisation curve can be explained by a change in electrocatalytic mechanism. Utilising a simple model to quantify the change in mechanisms, iR‐free results of the fuel cell experiments are fit and found to be represented by a common set of parameters. The change in mechanism is assumed to be a switch from four‐electron reduction of oxygen to water to a two‐electron reduction to hydrogen peroxide followed by disproportionation of the hydrogen peroxide to water and oxygen. The data is used to estimate a mass specific exchange current density towards the oxygen reduction reaction (ORR) to water in the range 10−11–10−13 A g−1 depending on the catalyst. For the reduction of oxygen to hydrogen peroxide, the mass specific exchange current density is estimated to be in the range 10−2–10−3 A g−1. Utilising the electrokinetic model, it is shown how the mass transport losses can be extracted from the polarisation curve. For all three catalyst layers studied, these mass transport losses reach about 100 mV at a current density of 1 A cm−2. Finally a discussion of the performance and site density requirements of the non‐precious metal catalysts are provided, and it is estimated that the activity towards the ORR needs to be increased by an order of magnitude, and the site density by two/three orders of magnitude to compete with platinum as an ORR electrocatalyst.

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RRDE and Voltammetric Study of ORR on Pyrolyzed Fe/Polyaniline Catalyst. On the Origins of Variable Tafel Slopes

Cited by 124 publications

References 73 publications

Graphene-based transition metal oxide nanocomposites for the oxygen reduction reaction

Graphene-based transition metal oxide nanocomposites for the oxygen reduction reaction

Effects of Axial Coordination of the Metal Center on the Activity of Iron Tetraphenylporphyrin as a Nonprecious Catalyst for Oxygen Reduction

Mechanistic Insights into the Oxygen Reduction Reaction on Metal–N–C Electrocatalysts under Fuel Cell Conditions

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