Erratum: Energy conversion catalysis using semiconducting transition metal cluster compounds

Carbon-supported Ir, Rh, IrSe, and RhSe were synthesized and subjected to electrochemical and physical (XRD, TEM) characterizations. ORR activity, peroxide generation, and methanol tolerance on carbon-supported Ir, Rh, IrSe, and RhSe were compared to a similarly prepared Pt and RuSe catalysts at comparable loading. Electrochemical characteristics of selenides studied using cyclic voltammetry and Cu stripping demonstrated complete suppression of the formation of oxygenated species and Hupd on the catalyst surface by Se. In presence of methanol, all selenides exhibited high methanol tolerance, and their oxygen reduction activities were in the order of Ir

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confidence: 96%

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confidence: 99%

Oxygen Reduction Reaction and Peroxide Generation on Ir, Rh, and their Selenides – A Comparison with Pt and RuSe

Neergat

Gunasekar

Singh

2011

“…Its high cost and poor availability, however, makes the development of non-noble metal catalysts highly desirable. While many studies have been done to develop non-platinum cathode catalysts for PEFCs, such as cobalt-or iron-based macrocyclic complexes (N 4 -chelate type such as phtalocyanines, porphyrins, and tetraazaanulens), [1][2][3] metal chalcogenides (Mo x Ru y Se z, Ru x X y (where X = S, Se, and Te)), [4][5][6][7][8] and carbon-based catalysts, [9][10][11] these compounds are, actually, unstable in acidic and oxidizing atmosphere, and less-stable than that of platinum based cathode catalysts. [11][12][13][14][15][16][17] In contrast, we have been focusing on the materials' stability to sever cathode conditions, viz., strong acidic and corrosive environments, and have developed the group 4 and 5 metal-oxidebased catalysts that have high ORR activities that are comparable to that of platinum, simultaneously exhibiting highly tolerant behaviors for the PEFC cathode condition.…”

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confidence: 99%

Factors for Improvements of Catalytic Activity of Zirconium Oxide-Based Oxygen-Reduction Electrocatalysts

Ohgi¹,

Ishihara²,

Matsuzawa³

et al. 2012

Partially oxidized zirconium carbonitrides (Zr-CNO) were evaluated as a non-precious-metal cathode used for polymer electrolyte fuel cells. The zirconium-oxide-based catalysts were prepared from zirconium carbonitrides under controlled oxygen partial pressures from 10 −2 to 10 −18 atm at 1000 • C. The ORR activity of Zr-CNO showed a volcano-like tendency against the degree of oxidation (DOO). We found a significant lattice-parameter decrease for highly active Zr-CNOs, and this could be ascribed for the formation of oxygen-and zirconium-vacancies in monoclinic ZrO 2 . On the other hand, carbon originated from starting materials was deposited on the surface of Zr-CNOs during the partial oxidation process. We also found that the oxygen content on the surface of highly active Zr-CNOs was drastically decreased when the amount of carbon significantly decreased during partial oxidation processes. This result indicates that the deposited carbon acted as a strong reduction agency. From XPS and XRD analyzes, there is a linear relationship between the ORR current and amount of oxygen vacancy formed in monoclinic phase. Therefore, we believe that oxygen vacancy formed in monoclinic phase could act as active sites for the ORR.Polymer electrolyte fuel cells (PEFCs) are efficient and clean electrochemical power generation devices that produce electricity from H 2 and O 2 gases. Platinum-based oxygen reduction reaction (ORR) catalysts are used as the best catalyst for cathodes of PEFCs at present. Its high cost and poor availability, however, makes the development of non-noble metal catalysts highly desirable. While many studies have been done to develop non-platinum cathode catalysts for PEFCs, such as cobalt-or iron-based macrocyclic complexes (N 4 -chelate type such as phtalocyanines, porphyrins, and tetraazaanulens), 1-3 metal chalcogenides (Mo x Ru y Se z, Ru x X y (where X = S, Se, and Te)), 4-8 and carbon-based catalysts, 9-11 these compounds are, actually, unstable in acidic and oxidizing atmosphere, and less-stable than that of platinum based cathode catalysts. [11][12][13][14][15][16][17] In contrast, we have been focusing on the materials' stability to sever cathode conditions, viz., strong acidic and corrosive environments, and have developed the group 4 and 5 metal-oxidebased catalysts that have high ORR activities that are comparable to that of platinum, simultaneously exhibiting highly tolerant behaviors for the PEFC cathode condition. [18][19][20][21][22][23][24] The results of our studies on transition-metal-oxide-based ORR catalysts have suggested that the best ORR activity is obtained when transition-metal carbonitrides, such as ZrC x N y , TaC x N y , NbC x N y , are partially oxidized. Since the transition metal oxides themselves show no remarkable ORR activity, carbon and/or nitrogen that are included in the starting materials should play a role in emergence and enhancement of ORR activity of oxide-based ORR catalysts.

“…Alonso-Vante et al found that Mo 4.2 Ru 1.8 Se 8 had a superior catalytic activity for the ORR in acidic media in 1986. 19 Extended X-ray absorption fine structure analysis revealed that an O 2 molecule ad-sorbed on Mo, Ru acted as an active center, and Se affected an electronic state and a local structure of Ru. 20 RuSe, RuTe, MoReSe, MoRhS, MoOsS, MoSe, ReRuS, IrRuS, ͑RuMo͒SeO, WRuSe, RhS, RhSe, RuCrSe, RuFeSe, and CoSe were investigated besides MoRuSe.…”

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confidence: 99%

Partially Oxidized Tantalum Carbonitrides as a New Nonplatinum Cathode for PEFC–1–

Ishihara

Shibata

Mitsushima

et al. 2008

Partially oxidized TaC0.58normalN0.42 has been investigated as a cathode for polymer electrolyte fuel cells (PEFCs). Catalytic activity for the oxygen reduction reaction (ORR) significantly depends on the oxidation state of TaC0.58normalN0.42 . TaC0.58normalN0.42 and Ta2normalO5 had a poor catalytic activity for the ORR. The onset potential on the partially oxidized TaC0.58normalN0.42 for the ORR had a maximum value of 0.83 V vs a reversible hydrogen electrode in 0.1moldm−3 normalH2SO4 at 30°C . X-ray diffraction analysis showed that the specimens, which had a definite catalytic activity for the ORR, had both TaCxnormalNy and Ta2normalO5 peaks. This result indicated that an appropriate oxidation of the TaC0.58normalN0.42 was essential to enhance the catalytic activity for the ORR.