Proton NMR and Dynamic Studies of Hydrous Ruthenium Oxide

Fu, Riqiang; Ma, Zhiru; Zheng, Jim P.

doi:10.1021/jp013860q

Cited by 78 publications

(68 citation statements)

References 31 publications

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“…This study suggests that the high proton-conducting nature of hydrous ruthenium oxide extends the proton-conduction path in the catalyst layer. This is in conformity with the findings of Fu et al 21 31 have measured activation energy for proton transport in Nafion using the same solid-state 1 H NMR technique. The E a value of dried Nafion is 16.4 kJ/mole, while that for hydrated Nafion is 11 kJ/mole.…”

Section: Resultssupporting

confidence: 91%

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PEFC Electrode with Enhanced Three-Phase Contact and Built-In Supercapacitive Behavior

Selvarani

Sahu

Kiruthika

et al. 2009

J. Electrochem. Soc.

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Hydrous ruthenium oxide, which exhibits both protonic and electronic conduction, is incorporated in the cathode electrocatalyst layer of the membrane electrode assembly for polymer electrolyte fuel cells ͑PEFCs͒. The supercapacitive behavior of ruthenium oxide helps realize a fuel cell-supercapacitor hybrid. Platinum ͑Pt͒ nanoparticles are deposited onto carbon-supported hydrous ruthenium oxide and the resulting electrocatalyst is subjected to both physical and electrochemical characterization. Powder X-ray diffraction and transmission electron microscopy reflect the hydrous ruthenium oxide to be amorphous and well-dispersed onto the catalyst. X-ray photoelectron spectroscopy data confirm that the oxidation state of ruthenium in Pt anchored on carbon-supported hydrous ruthenium oxide is Ru 4+ . Electrochemical studies, namely cyclic voltammetry, cell polarization, intrinsic proton conductivity, and impedance measurements, suggest that the proton-conducting nature of hydrous ruthenium oxide helps extend the three-phase boundary in the catalyst layer, which facilitates improvement in performance of the PEFC. The aforesaid PEFC operating with hydrogen fuel and oxygen as oxidant shows a higher power density ͑0.62 W/cm 2 @ 0.6 V͒ in relation to the PEFC comprising carbon-supported Pt electrodes ͑0.4 W/cm 2 @ 0.6 V͒. Potential square-wave voltammetry study corroborates that the supercapacitive behavior of hydrous ruthenium oxide helps ameliorate the pulse-power output of the fuel cell. In the postoil energy economy, hydrogen-based fuel cells are being perceived as a possible energy alternative. Hydrogen-based polymer electrolyte fuel cells ͑PEFCs͒ are most promising as they offer an order of magnitude higher power density than any other fuel cell system. A PEFC is fed with hydrogen, which is oxidized at the anode and oxygen that is reduced at the cathode. The protons released during the oxidation of hydrogen pass through the proton exchange membrane to the cathode. The electrons released during the oxidation of hydrogen travel through the external electric circuit, generating an electric current. Owing to the high degree of irreversibility of the oxygen reduction, even under open-circuit condition, the overpotential of the oxygen electrode in a PEFC happens to be about 0.2 V. This represents a loss of about 20% from the theoretical maximum efficiency for a PEFC. Accordingly, the PEFC cathode electrocatalyst has to possess a high intrinsic activity for the electrochemical reduction of oxygen at the cathode in order to attain the maximum efficiency of the PEFC. 1,2The activity of the cathode catalyst is reportedly improved by design of the tailored catalyst with controlled composition and microstructure. Nevertheless, the high activity of the catalyst itself is necessary, but not a sufficient condition for good fuel cell performance. To ensure the optimum conditions for effective catalyst utilization, an environment must be provided that allows for an adequate supply of reactants as well as good connectivity of the acti...

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Section: Resultssupporting

confidence: 91%

“…It is reported that amorphous ruthenium oxide with annealing at a critical temperature close to its crystalline temperature ͑ϳ150°C͒ shows optimum protonic and electronic conductivity. 18,19,21 Accordingly, in the present study, hydrous ruthenium oxide annealed at 150°C is used.…”

Section: Resultsmentioning

confidence: 99%

PEFC Electrode with Enhanced Three-Phase Contact and Built-In Supercapacitive Behavior

Selvarani

Sahu

Kiruthika

et al. 2009

J. Electrochem. Soc.

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“…The mechanisms of energy storage for supercapacitors could be classified into two groups: (i) charge/discharge of the nonFaradaic electrical double layers due to charge separation at the electrode material-electrolyte interface [1][2][3][9][10][11]; and (ii) the charge transfer of electroactive species within electrode materials through Faradaic redox reactions [1][2][3][12][13][14][15][16]. In order to promote the energy density of supercapacitors (based on either weight or volume), the devices of the latter kind are recommended [3], which have been recognized as supercapacitors of next generation.…”

Section: Introductionmentioning

confidence: 99%

“…The above studies tried to develop simple, effective methods for synthesizing amorphous or crystalline RuO 2 or a better utilization of RuO 2 ·xH 2 O for this application. Moreover, several important studies gain a deep understanding on the charge storage/delivery mechanism of RuO 2 ·xH 2 O [15,16,31,32]. Based on these studies, how to design a RuO 2 -based material in order to achieve the highest utilization of RuO 2 or the maximum power delivery becomes possible.…”

Section: Introductionmentioning

confidence: 99%

A comparison study of the capacitive behavior for sol–gel-derived and co-annealed ruthenium–tin oxide composites

Wang

Chang

2007

Electrochimica Acta

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“…It was reported that cation diffusion in hydrated electrodes could occur via hopping of alkaline ions and H + ions between H 2 O and OH À sites, suggesting that the hydrogen atoms were relatively mobile in RuO 2 ÁxH 2 O samples as compared to those in rigid samples. 196 Thus, the combined water in RuO 2 is expected to enhance the diffusion of cations inside the electrode layer.…”

mentioning

confidence: 99%

A review of electrode materials for electrochemical supercapacitors

2012

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Proton NMR and Dynamic Studies of Hydrous Ruthenium Oxide

Cited by 78 publications

References 31 publications

PEFC Electrode with Enhanced Three-Phase Contact and Built-In Supercapacitive Behavior

PEFC Electrode with Enhanced Three-Phase Contact and Built-In Supercapacitive Behavior

A comparison study of the capacitive behavior for sol–gel-derived and co-annealed ruthenium–tin oxide composites

A review of electrode materials for electrochemical supercapacitors

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