Investigation of the Kinetics and Mechanism of Co‐Porphyrin Catalyzed Oxygen Reduction by Hydrophobic Carbon‐Ceramic Electrodes

Tsionsky, Michael; Lev, Ovadia

doi:10.1149/1.2044263

Cited by 37 publications

(18 citation statements)

References 7 publications

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“…However, a varying catalyst layer porosity may also be influencing these measured Tafel slopes. 50 Optimization of heat-treatment temperature of ORR catalysts.-Based on earlier work with catalysts derived from Co-and Fe-based macrocyles, 13,[15][16][17]22,25,27,31,51 heat-treatment in an inert atmosphere was expected to improve both the ORR activity and the stability of our catalysts. As has been shown in our previous work, 40 this is true for our sol-derived catalysts as well.…”

Section: Resultsmentioning

confidence: 99%

Effect of Preparation Conditions of Sol–Gel-Derived Co–N–C-Based Catalysts on ORR Activity in Acidic Solutions

Sirk

Campbell

Birss

2008

J. Electrochem. Soc.

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Using a Co oxide ethanol-based sol as a precursor solution, nitrogen ͑N͒-and carbon ͑C͒-containing ligands ͓1,2 phenylene diamine ͑phen͒ and ethylene diamine ͑en͔͒ were added to produce an oxygen reduction reaction ͑ORR͒ catalyst precursor. After adsorption on carbon powder, heat-treatment in an inert atmosphere at 500-900°C, and the addition of Nafion as a binder, the powdered mixture was coated on a glassy carbon electrode and evaluated for its ORR activity in 0.5 M H 2 SO 4 . The catalystcarbon powder ratio, heat-treatment temperature, ligand type, and ligand:Co ratio were optimized, and the effect of increased catalyst layer thickness, particle size, and C support was also determined. It was concluded that a phen-based catalyst with a metal to ligand ratio of 1:2, a heat-treatment at 900°C, and a concentration of 4 wt % Co was the most active, selective, and stable ORR catalyst material of the materials developed in the present work. X-ray photoelectron spectroscopy and X-ray diffraction analysis showed the formation of both Co metal and CoN 4 units upon heat-treatment, with the most active catalyst having a 5.3:1 overall N-Co ratio.

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Section: Resultsmentioning

confidence: 99%

Effect of Preparation Conditions of Sol–Gel-Derived Co–N–C-Based Catalysts on ORR Activity in Acidic Solutions

Sirk

Campbell

Birss

2008

J. Electrochem. Soc.

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“…The weight ratio of perovskite to carbon was fixed at 25:75 in this study because good cathodic performance has been reported with this composition." 9 The catalyst and carbon were mixed with two or three drops Triton X-100 (Spectrum Chemical Co.) as a surfactant and 0.2 to 1 ml dilute PTFE suspension (TFE-30, DuPont) as a binder with an ultrasonic horn to form a uniform slurry. The slurry was then pasted onto the gas diffusion layer.…”

Section: Methodsmentioning

confidence: 99%

Thermal Treatment of La0.6Ca0.4CoO3 Perovskites for Bifunctional Air Electrodes

Lee

Striebel

McLarnon

et al. 1997

J. Electrochem. Soc.

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The perovskite La 6,Ca,0 CoO, has been of interest as a bifunctional electrocatalyst for the bifunctional air electrode. The calcination and subsequent cooling steps in the amorphous citrate precursor (ACP) process have been optimized to prepare La6,Ca0.,CoO, powders with high surface area, and consequently improved electrocatalytic performance in an air electrode. The surface area of the final powder depends on the thermal treatment and the surface area increases with increasing the cooling rate. A sample quenched rapidly from 650°C had a surface area of 33 m'/g, which is more than double the value obtained with a slower cooling rate. Polytetrafluorene-ethylene (PTFE) bonded gas diffusion electrodes loaded with La,,Ca,,CoO 3 catalysts prepared by the ACP method show good bifunctional performance. An electrode loaded with only 10 mg/cm 2 of powder prepared by quenching from 650°C showed the best bifunctional performance, i.e., 280 mA/cm 2 for oxygen reduction and 300 mA/cm3 for the oxygen evolution, at 0.6 and 1.6 V vs. RHE, respectively. This performance compares well with results from lower area La ,Ca,0 CoO, at much higher loadings.

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“…Although reaction [4] is not electrochemical, reaction [3] would affect the efficiency of the electrochemical oxygen reduction on the catalyst. That is to say, both reactions [2] and [3] , which can proceed the 2+2 electron reduction, play an important role in the oxygen reduction in acidic solutions.…”

Section: -3 Preparation Of Electrode Assemblymentioning

confidence: 99%

Oxygen Reduction Activity of Thermally Decomposed Tetraphenylporphyrin as Cathode Catalyst of DMFC

Taguchi

Tamori

2006

Int. J. Soc. Mater. Eng. Resour

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DMFC has a serious technical problem, which is called "crossover". The crossover CH3OH, which passes through the polymer electrolyte from the anode to cathode, usually adsorbs on the surface of the cathode catalyst (Pt black) that decreases the DMFC performance. In this study, tetraphenylporphine and tetraphenylporphyrin-metals (metals: Co, Mn and Ru) were thermally decomposed at 673-1173 K for 7.2 ks and the activity of the oxygen reduction of the product was investigated using a rotating disk electrode in order to develop a new cathode catalyst with CH3OH tolerance. The thermally decomposed TPP-Co and TPP-Ru, which have no activity toward CH3OH oxidation, are possible materials as the cathode catalyst of the DMFC, thus being a substitute for the Pt black.

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Investigation of the Kinetics and Mechanism of Co‐Porphyrin Catalyzed Oxygen Reduction by Hydrophobic Carbon‐Ceramic Electrodes

Cited by 37 publications

References 7 publications

Effect of Preparation Conditions of Sol–Gel-Derived Co–N–C-Based Catalysts on ORR Activity in Acidic Solutions

Effect of Preparation Conditions of Sol–Gel-Derived Co–N–C-Based Catalysts on ORR Activity in Acidic Solutions

Thermal Treatment of La0.6Ca0.4CoO3 Perovskites for Bifunctional Air Electrodes

Oxygen Reduction Activity of Thermally Decomposed Tetraphenylporphyrin as Cathode Catalyst of DMFC

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