Electrocatalysts for hydrogen oxidation

At temperatures below about 125°C, CO adsorption on platinum is very strong. Even few ppms in the H2 stream cause substantial performance losses on the anode. Therefore, the use of platinum alone is not viable for HOR in the presence of CO in low temperature fuel cells. Thus, platinum-ruthenium, platinum-molybdenum and platinum-tin are being used as anode electrocatalysts for hydrogen oxidation in the presence of CO because they tolerate low ppms of CO without excessive polarization losses. Timgsten carbide (WC) also shows high CO-tolerance [38,44]. 

Bae, S.J., Kim, S.-J., Park, J.I., Lee, J.-H., Cho, H., and Park, J.-Y. (2010) Lifetime prediction through accelerated degradation testing of membrane electrode assemblies in direct methanol fuel cells. Int.J. Hydrogen Energy, 35, 9166-9176. Shao, M. (2011) Palladium-based electrocatalysts for hydrogen oxidation and oxygen reduction reactions. J. Power Sources, 196, 2433-2444. 

Shao MH (2011) Palladium-based electrocatalysts for hydrogen oxidation and oxygen reduction reactions. J Power Sources 196 2433-2444... 

Shao M., Palladium electrocatalysts for hydrogen oxidation and oxygen tednction reactions, J. Power Sources, 196, 2433 (2011). 

Several activities, if successful, would strongly boost the prospects for fuel ceU technology. These include the development of (/) an active electrocatalyst for the direct electrochemical oxidation of methanol (2) improved electrocatalysts for oxygen reduction and (2) a more CO-tolerant electrocatalyst for hydrogen. A comprehensive assessment of the research needs for advancing fuel ceU technologies, conducted in the 1980s, is available (22). 

IX. DEVELOPMENT OF ALLOY ELECTROCATALYSTS FOR HYDROGEN MOLECULE OXIDATION... 

Shaw WJ, Helm ML, DuBois DL (2013) A modular, tmergy-based approach to the development of niekel eontaining moleeular electrocatalysts for hydrogen production and oxidation. Bioenergetics 1827(8-9) 123-1139. doi 10.1016/j.bbabio.2013.01.003... 

Ginovska-Pangovska B, Dutta A, Reback ML, Linehan JC, Shaw WJ (2014) Beyond the active site the impact of the outer coordination sphere on electrocatalysts for hydrogen production and oxidation. Acc Chem Res 47(8) 2621-2630. doi 10.1021/ar5001742... 

Zhang L, Kim J, Chen HM, Nan F, Dudeck K, Liu RS, et al. A novel CO-tolerant PtRu core—shell structured electrocatalyst with Ru rich in core and Pt rich in shell for hydrogen oxidation reaction and its implication in proton exchange membrane fuel cell. J Power Sources 2011]196[22) 9in—23. 

A small amount of Pt was loaded on WC, and the Pt/WC electrocatalyst was tested for hydrogen oxidation. Electrocataljdic activities can be evaluated by measuring electrochemical active surface area (EAS, m /gpt) from cyclovoltammetry. 10 wt% Pt/WC prepared via TPRe of various tungsten oxide based precursors showed 5.9-11.4 m /gpt in 0.5 Af H2SO4 electrolyte at room temperature (28). 7.5 wt% Pt/W2C and Pt/WC fabricated by polymer-induced carburization led to high EAS value of 327 m /gpt (33) and 316 m /gpt (34) in 1 Af H2SO4 electrolyte. 

Transition metal carbides and nitrides are two major kinds of electrode materials. This is due to their good electrical conductivity, corrosion resistance, and electrocatalytic activity. In the past several decades, some studies have been done on these materials as electrocatalysts for hydrogen and methanol oxidation and oxygen reduction reactions in alkaline and acid solutions [59-63]. This section will briefly review transition metal carbides and nitrides and then introduce current state-of-the-art catalysts explored in acidic media. 

Stonehart P. Electrocatalyst advances for hydrogen oxidation in phosphorie aeid fuel cells. J Hydrogen Energy 1984 9 921-8. 

The hydrogen (H2)/oxygen (-02 ) anode/cathode combination is the most highly developed fuel cell. It continues to be an essential power source for manned space missions, which accounts for its advanced state of development. Beyond the practical problem of a gaseous fuel (H2), both electrode reactions require precious-metal catalysts (usually platinum supported on porous carbon electrodes). As indicated in earlier sections, electrochemistry is limited to pathways that involve one electron steps. Hence, the essential function of the electrocatalysts for H2 oxidation and -02- reduction is to provide such pathways for these multi-electron transformations. 

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