Metalloporphyrin Catalysts of Oxygen Reduction

Boulatov, Roman

doi:10.1002/9780470463772.ch18

Cited by 13 publications

(24 citation statements)

References 117 publications

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“…This desorption of H 2 O 2 into the bulk electrolyte due to its weak binding on the active site is the primary source of peroxide detected at the ring in acidic media. At very high overpotentials (<0.3 V), the ORR process in acidic electrolyte becomes very efficient and consequently the peroxide detected decreases [71,72]. The ring current profile in 0.1 M NaOH is more complex.…”

Section: Pyrolyzed Metal Macrocycle For Promoting Inner-sphere Electrmentioning

confidence: 99%

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Fundamental Mechanistic Understanding of Electrocatalysis of Oxygen Reduction on Pt and Non-Pt Surfaces: Acid versus Alkaline Media

Ramaswamy

Mukerjee

2012

Advances in Physical Chemistry

339

255

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Complex electrochemical reactions such as Oxygen Reduction Reaction (ORR) involving multi-electron transfer is an electrocatalytic inner-sphere electron transfer process that exhibit strong dependence on the nature of the electrode surface. This criterion (along with required stability in acidic electrolytes) has largely limited ORR catalysts to the platinum-based surfaces. New evidence in alkaline media, discussed here, throws light on the involvement of surface-independent outer-sphere electron transfer component in the overall electrocatalytic process. This surface non-specificity gives rise to the possibility of using a wide-range of non-noble metal surfaces as electrode materials for ORR in alkaline media. However, this outer-sphere process predominantly leads only to peroxide intermediate as the final product. The importance of promoting the electrocatalytic inner-sphere electron transfer by facilitation of direct adsorption of molecular oxygen on the active site is emphasized by using pyrolyzed metal porphyrins as electrocatalysts. A comparison of ORR reaction mechanisms between acidic and alkaline conditions is elucidated here. The primary advantage of performing ORR in alkaline media is found to be the enhanced activation of the peroxide intermediate on the active site that enables the complete four-electron transfer. ORR reaction schemes involving both outer-and inner-sphere electron transfer mechanisms are proposed.

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Section: Pyrolyzed Metal Macrocycle For Promoting Inner-sphere Electrmentioning

confidence: 99%

“…Based on the above experimental results, the following reaction scheme is proposed for ORR in dilute alkaline media on heat-treated FeTPP/C catalyst. Similar set of reactions can be developed, mutatis mutandis, for dilute acidic media [22,71,72,86]. Equation …”

Section: ≥600mentioning

confidence: 99%

Fundamental Mechanistic Understanding of Electrocatalysis of Oxygen Reduction on Pt and Non-Pt Surfaces: Acid versus Alkaline Media

Ramaswamy

Mukerjee

2012

Advances in Physical Chemistry

339

255

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“…The predominance of heme in aerobic metabolism over the past two billion years justifies a serious look at metalloporphyrins as potential ORR catalysts for low temperature fuel cells [24,25].…”

Section: Characterization Of Catalystsmentioning

confidence: 99%

Study of pyrolyzed hemin/C as non-platinum cathodic catalyst for direct methanol fuel cells

et al. 2010

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Biological reduction of O-2 to H2O justifies a serious look at heme as a potential O-2 reduction reaction (ORR) catalyst for low temperature fuel cells. In this study, a novel non-platinum electrocatalyst for ORR was prepared through hemin, which is hydrochloride of heme, supported on Black Pearls 2000 carbon black (Hm-BP) pyrolyzed at 700-900 A degrees C in Ar atmosphere. The physical and electrocatalytic properties of as-prepared catalysts were characterized by TGA, XRD, XPS, TEM, rotating disk electrode (RDE) and rotating ring disk electrode (RRDE). It has found that the catalyst treated at 750 A degrees C (Hm-BP-750) exhibits the best property among the Hm-BP catalysts prepared. The onset potential of ORR on the Hm-BP-750 at 30 A degrees C was measured ca. 0.90 V (vs. RHE) in 0.1 M H2SO4, and mass current density was reached 15.3 mA mg(-1) at 0.75 V. It has revealed that O-2 could be reduced directly to water in a 4e process between 0.9 and 0.83V, and the yield of H2O2 was 0-18% in the potential range of 0.83-0.63 V. This methanol-tolerant catalyst also presents excellent stability in medium-term test of direct methanol fuel cell at 80 A degrees C.National Natural Science Foundation of China [20933004, 20833005, 20921120405

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“…Synthetic metalloporphyrins are common molecular ORR catalysts inspired by the heme-based cofactors. 15 However, platinum still remains the first choice as an electrocatalyst for current fuel cells despite its high cost and low abundance. Various SOD-modified catalysts have been investigated for their ORR performances.…”

Section: Introductionmentioning

confidence: 99%

Mechanistic Study of the Conversion of Superoxide to Oxygen and Hydrogen Peroxide in Carbon Nanoparticles

Jalilov

Zhang

Samuel

et al. 2016

ACS Appl. Mater. Interfaces

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Hydrophilic carbon clusters (HCCs) are oxidized carbon nanoparticles with a high affinity for electrons. The electron accepting strength of HCCs, employing the efficient conversion of superoxide (O2•–) to molecular oxygen (O2) via single-electron oxidation, was monitored using cyclic voltammetry and electron paramagnetic resonance spectroscopy. We found that HCCs possess O2 reduction reaction (ORR) capabilities through a two-electron process with the formation of H2O2. By comparing results from aprotic solvents to those obtained from ORR activity in aqueous media, we propose a mechanism for the origin of the antioxidant and superoxide dismutase mimetic properties of poly(ethylene glycolated) hydrophilic carbon clusters (PEG-HCCs).

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Metalloporphyrin Catalysts of Oxygen Reduction

Cited by 13 publications

References 117 publications

Fundamental Mechanistic Understanding of Electrocatalysis of Oxygen Reduction on Pt and Non-Pt Surfaces: Acid versus Alkaline Media

Fundamental Mechanistic Understanding of Electrocatalysis of Oxygen Reduction on Pt and Non-Pt Surfaces: Acid versus Alkaline Media

Study of pyrolyzed hemin/C as non-platinum cathodic catalyst for direct methanol fuel cells

Mechanistic Study of the Conversion of Superoxide to Oxygen and Hydrogen Peroxide in Carbon Nanoparticles

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