The electroreduction of oxygen on pyrolytic graphite

Paliteiro, Carlos; Hamnett, A.; Goodenough, John B

doi:10.1016/0022-0728(87)85012-x

Cited by 84 publications

(54 citation statements)

References 21 publications

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“…There are two waves in the CV curve, possibly corresponding to two active sites for the ORR, which is consistent with literature experiments on GC, 41,42 on the roughened basal plane of graphite 43 and on the edge of pyrolytic graphite. 44,45 The two waves were also observed in the CV curves of the as-sputtered C film and the C films heated at all temperatures up to 1000°C ͑not shown here͒. These results suggest that the assputtered C film and the C films heated up to 1000°C are disordered, 42,46 which agrees with the XRD measurements on these films that show no clear Bragg peaks ͑not shown͒.…”

Section: Proof Copy [Jes-07-1182r] 069801jes Proof Copy [Jes-07-1182rsupporting

confidence: 79%

Final Report - Novel Approach to Non-Precious Metal Catalysts

Atanasoski¹

2007

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This project was directed at reducing the dependence of PEM fuel cell catalysts on precious metals. The primary motivation was to reduce the cost of the fuel cell stack as well as the overall system cost without loss of performance or durability. Platinum is currently the catalyst of choice for both the anode and the cathode. However, the oxygen reduction reaction (ORR) which takes place on the cathode is an inherently slower reaction compared to the hydrogen oxidation reaction (HOR) which takes place on the anode. Therefore, more platinum is needed on the cathode than on the anode to achieve suitable fuel cell performance. As a result, developing a replacement for platinum on the cathode side will have a larger impact on overall stack cost.The drawbacks of using platinum as an ORR catalyst include its price, scarcity, and susceptibility to forming oxides at voltages of interest for efficient fuel cell operation. The price of platinum has more than doubled during the time period between the drafting of the proposal for this project and its completion. The monthly average price in the beginning of 2003 was $620/troy oz and the present price is $1450/troy oz. At these numbers and the 2010 DOE targets of 0.2 g Pt/kW and $30/kW, the cost of fuel cell stack would be over 30% due to platinum. Thus, the specific objectives of the project, as stated in the solicitation, were to produce non-precious metal (NPM) cathode catalysts which reduce dependence on precious metals (especially Pt), perform as well as conventional precious metal catalysts currently in use in MEAs, cost 50% less compared to a target of 0.2 g Pt/peak kW, and demonstrate durability of greater than 2000 hours with less than 10% power degradation. During the term of the project, DOE refined its targets for NPM catalyst activity to encompass volumetric current density. The DOE Multi-Year RD&D Plan (2005) volumetric current density targets for 2010 and 2015 are greater than 130 A/cm 3 and 300 A/cm 3 at 800 mV (IR-free) respectively.The initial approach to achieve these targets was to use vacuum deposition techniques to deposit transition metal, carbon and nitrogen moieties onto 3M's nanostructured thin film (NSTF) catalyst support. While this approach yielded compounds with similar physicochemical characteristics as catalysts reported by others as active for ORR, the activity of these vacuum deposited catalysts was not satisfactory. In order to enhance catalytic activity additional process steps were introduced, the most successful of which was a thermal treatment. To withstand high temperatures (~900 ºC), alternative supports to NSTF were introduced. A variety of carbon fabrics were tested for this purpose. Vacuum deposited materials were used as precursors and physicochemically transformed via thermal treatment to produce substantially better catalytic activity. This activity was further amplified by increasing the surface area of the carbon fabrics which lead to significant gains in fuel cell performance.iii The second synthetic approach was based on 3M...

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Section: Proof Copy [Jes-07-1182r] 069801jes Proof Copy [Jes-07-1182rsupporting

confidence: 79%

Final Report - Novel Approach to Non-Precious Metal Catalysts

Atanasoski¹

2007

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“…The use of carbon-based electrodes as cathodes for O 2 reduction instead of the more commonly used Pt has recently been reported by several groups (Paliteiro et al, 1987;Zimmerman and Wightman, 1991;Lowry et al, 1996). An example of the response of a CPE held at − 550 mV, the peak potential for O 2 reduction at CPEs (Lowry et al, 1996), to a 5-min tail pinch is shown in Fig.…”

Section: Resultsmentioning

confidence: 99%

Measurement of brain tissue oxygen at a carbon paste electrode can serve as an index of increases in regional cerebral blood flow

Lowry

Boutelle

Fillenz

1997

Journal of Neuroscience Methods

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Simultaneous monitoring of tissue O 2 and regional cerebral blood flow (rCBF) was performed in the striatum of freely-moving rats. Differential pulse amperometry and constant potential amperometry were used to monitor O 2 levels at a carbon paste electrode (CPE), while rCBF values were obtained using the H 2 clearance technique. Two forms of behavioural activation were studied and the resultant changes in tissue O 2 and blood flow compared. Both tail pinch and induced grooming produced immediate and parallel increases in O 2 and blood flow which returned to baseline on cessation of activity. These findings indicate that under conditions of physiological stimulation the direct voltammetric measurement of O 2 in brain tissue with a CPE can be used as a reliable index of increases in rCBF, resulting in an improvement in time resolution from 5 min (H 2 clearance) to B1 s (amperometry). Because tissue O 2 is a balance between supply by the blood stream and utilisation by the cells, increases in O 2 current are an index of increased blood flow only when supply significantly exceeds utilisation. © 1997 Elsevier Science B.V.

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“…Oxidative pre-treatments lead to an increase of the oxygen reduction rate due to electrocatalysis by oxygen containing surface species [26,29,66]. Oxidised carbon surfaces also catalyse the further reduction of hydrogen peroxide in alkaline solutions [29,57]. The enhancement of quinone-hydroquinone adsorption on GC electrodes after oxidising treatment in a 1:1 concentrated nitric acid-sulphuric acid mixture has been reported by Gomathi and Rao [87].…”

Section: Effect Of Pre-treatment On the Oxygen Reduction Reaction At mentioning

confidence: 85%

“…It is proposed that oxides may enhance adsorption of O 2 -by withdrawing electrons from the surface. It was observed that polarisation curves of glassy carbon and polished pyrolytic carbon show two peaks in oxygen-saturated alkaline solutions [26,57,58] corresponding to the oxygen reduction on two different surface sites. The current of the first peak does not reach the diffusional value and is limited by number of the most active surface catalytic sites.…”

Section: Effect Of Electrode Substrate On Oxygen Reduction Reaction Amentioning

confidence: 99%

“…Since the O 2 -adsorption is crucial to increase the rate of reaction (25) and therefore the production of hydrogen peroxide, adsorbates that partially blocked adsorption, like BMB or DNPH, slow down the reaction and shift the oxygen reduction peak potential toward more negative values. The effect of oxidative pre-treatment on the electrocatalytic activity of carbon electrode toward oxygen reduction has been reported by several authors [26,29,57,86,87]. Oxidative pre-treatments lead to an increase of the oxygen reduction rate due to electrocatalysis by oxygen containing surface species [26,29,66].…”

Section: Effect Of Pre-treatment On the Oxygen Reduction Reaction At mentioning

confidence: 99%

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