Development of group 4 and 5 metal oxide-based cathodes for polymer electrolyte fuel cell

Ota, Ken Ichiro; Ohgi, Yoshiro; Nam, Kyung Don; Matsuzawa, Koichi; Mitsushima, Shigenori; Ishihara, Akimitsu

doi:10.1016/j.jpowsour.2010.09.021

Cited by 63 publications

(56 citation statements)

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“…[1,2] Direct alcohol fuel cells (DAFCs) will presumably reach wide-scale commercialization earlier than hydrogen-fuelled cells owing to the easy handling and high energy density of organic fuels, especially covering portable power application (laptops, mobile phones, etc.) [22][23][24] These oxides are characterized by excellent stability in acid media. Application of DAFCs in portable and APU devices can accelerate the fuel-cell technology diffusion.…”

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confidence: 99%

Graphene‐Supported Substoichiometric Sodium Tantalate as a Methanol‐Tolerant, Non‐Noble‐Metal Catalyst for the Electroreduction of Oxygen

et al. 2015

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For the oxygen reduction reaction (ORR) in acidic medium, a good combination of an active and stable catalyst highly dispersed on a conductive and durable support is required. Moreover, for direct methanol fuel-cell applications, a suitable tolerance to methanol poisoning is also necessary. In this communication, we report on a new graphene-supported sodium tantalate (Na 2 Ta 8 O 21Àx ) electrocatalyst obtained at high temperature and characterized by significant substoichiometry. The synthesis includes the precipitation of tantalum oxide on a high surface area graphene and subsequent thermal treatment at 900 8C. A novel sodium tantalate phase with oxygen vacancies is thereafter obtained. This catalyst formulation shows promising activity towards the ORR especially in the presence of a high methanol concentration, as evidenced by a high tolerance to methanol poisoning. Accelerated stress tests and chemical leaching experiments also show the remarkable stability of the catalyst. This material presents good perspectives for application in cost-effective fuel cells.A highly active, durable, and cost-effective catalyst for the oxygen reduction reaction (ORR) is essential for the large-scale application of low-temperature fuel cells. State-of-the-art catalysts for fuel cells are based on precious metals, essentially platinum (Pt). The prohibitive cost of Pt, its scarce resources, and its insufficient durability hinder the commercialization of this fuel-cell technology. [1,2] Direct alcohol fuel cells (DAFCs) will presumably reach wide-scale commercialization earlier than hydrogen-fuelled cells owing to the easy handling and high energy density of organic fuels, especially covering portable power application (laptops, mobile phones, etc.) and auxiliary power units (APUs). Application of DAFCs in portable and APU devices can accelerate the fuel-cell technology diffusion. [2,3] In the case of a DAFC, the poisoning effect of the alcohol that permeates through the membrane is an additional concern to the sluggishness of the electrochemical reactions at both the anode and the cathode. [3,4] Now, only a few types of electrocatalysts based on nonprecious metal formulations have been found to be active towards the ORR in acid media. These include carbon-supported transition-metal/nitrogen compounds (Fe/N/C, Co/N/C), [5][6][7][8][9][10][11] metal-free nitrogen-doped carbon materials, [12,13] and transition-metal chalcogenides. [14,15] Although Fe-and Co-based catalysts have been studied for the ORR for over 50 years, a suitable enhancement in the catalytic activity has been achieved only very recently. [5,8,16] These catalysts are potential competitors to Pt in terms of activity, [5,8] whereas significant efforts are still required to further enhance their stability. [6,7] Piela et al. have also reported promising tolerance to methanol poisoning for a Co-based catalyst. [17] Graphene, a free-standing atomic thin layer of sp 2 carbon atoms, has emerged as the most interesting carbon material in the last decade because of its unp...

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Graphene‐Supported Substoichiometric Sodium Tantalate as a Methanol‐Tolerant, Non‐Noble‐Metal Catalyst for the Electroreduction of Oxygen

et al. 2015

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“…1 Thus, to overcome the large overpotential, platinum catalysts are used. As non-platinum catalysts, Fe and Co complex catalysts, [11][12][13][14] carbon based catalysts, [15][16][17][18][19][20][21] transition metal oxides, nitrides, and oxynitride catalysts, [22][23][24][25][26][27][28][29][30][31][32][33][34][35] such as Ta 3 N 5 , TaNO, TaCNO, ZrO x N y , and NbO x N y , have been reported. [2][3][4][5] However, platinum is a precious metal that limits the widespread use of PEFCs; therefore, low-platinum or non-platinum catalysts for ORR have been required, and various types of catalysts have been reported.…”

Section: Introductionmentioning

confidence: 99%

Theoretical studies on the mechanism of oxygen reduction reaction on clean and O-substituted Ta₃N₅(100) surfaces

Watanabe

Ushiyama

Yamashita

2015

Catal. Sci. Technol.

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The reaction mechanism of oxygen reduction reaction (ORR) on Ta 3 N 5 Ĳ100) surfaces was examined theoretically. In particular, the effects of O-substitution on the catalytic activity have been discussed. First, the adsorption energy and geometry of an oxygen molecule adsorbed on a clean and an O-substituted Ta 3 N 5 Ĳ100) surface were calculated. Energy diagrams for 2-electron and 4-electron reactions on clean and O-substituted Ta 3 N 5 Ĳ100) surfaces were then examined. The results show that the adsorption energy of an oxygen molecule on the clean Ta 3 N 5 Ĳ100) surface is almost zero and the oxygen molecule is easier to adsorb on the O-substituted surface. However, OH and H 2 O adsorb strongly on the O-substituted surfaces so that their desorption can be the rate-determining step. To improve the ORR activity, both O 2 and OH adsorption energies should be tuned. By analysis of the energy level of adsorbates and Ta 3 N 5 O-substituted surface, the impurity state of Ta 3 N 5 is found to be the key descriptor for the adsorption energy. Therefore, the ORR activity can be controlled by changing the energy of the impurity state.

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“…Moreover, heat-treatment of the oxides under a reducible atmosphere, e.g., under hydrogen, increases not only the amount of oxide ion vacancies but also the electric conductivity, as has been utilized to control the electric properties of n-type titanium dioxides, TiO2-x. The oxide ion vacancy may act as the active sites for the ORR [14,17,19]; that is, the electron density of the surface metal ions surrounding the oxide ion vacancy will be enhanced compared to the other normal metal ions on the surface, and they may behave as adsorption sites for oxygen molecules [23]. Concerning the potential for resistance (b) pointed out above, the interface between the oxide coating and the titanium support formed by the dip-coating is usually stable; that is, the oxide coating adheres to the titanium substrate strongly, forming a mixed oxide interface layer.…”

Section: °Cmentioning

confidence: 99%

A gas-diffusion cathode coated with oxide-catalyst for polymer electrolyte fuel cells using neither platinum catalyst nor carbon catalyst-support

Takasu

Fukunaga

Yang

et al. 2013

Electrochimica Acta

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Development of group 4 and 5 metal oxide-based cathodes for polymer electrolyte fuel cell

Cited by 63 publications

References 56 publications

Graphene‐Supported Substoichiometric Sodium Tantalate as a Methanol‐Tolerant, Non‐Noble‐Metal Catalyst for the Electroreduction of Oxygen

Graphene‐Supported Substoichiometric Sodium Tantalate as a Methanol‐Tolerant, Non‐Noble‐Metal Catalyst for the Electroreduction of Oxygen

Theoretical studies on the mechanism of oxygen reduction reaction on clean and O-substituted Ta₃N₅(100) surfaces

A gas-diffusion cathode coated with oxide-catalyst for polymer electrolyte fuel cells using neither platinum catalyst nor carbon catalyst-support

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Development of group 4 and 5 metal oxide-based cathodes for polymer electrolyte fuel cell

Cited by 63 publications

References 56 publications

Graphene‐Supported Substoichiometric Sodium Tantalate as a Methanol‐Tolerant, Non‐Noble‐Metal Catalyst for the Electroreduction of Oxygen

Graphene‐Supported Substoichiometric Sodium Tantalate as a Methanol‐Tolerant, Non‐Noble‐Metal Catalyst for the Electroreduction of Oxygen

Theoretical studies on the mechanism of oxygen reduction reaction on clean and O-substituted Ta3N5(100) surfaces

A gas-diffusion cathode coated with oxide-catalyst for polymer electrolyte fuel cells using neither platinum catalyst nor carbon catalyst-support

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Theoretical studies on the mechanism of oxygen reduction reaction on clean and O-substituted Ta₃N₅(100) surfaces