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Highly Active, CO-Tolerant, and Robust Hydrogen Anode Catalysts: Pt–M (M = Fe, Co, Ni) Alloys with Stabilized Pt-Skin Layers

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journal contribution
posted on 06.12.2016, 18:23 by Guoyu Shi, Hiroshi Yano, Donald A. Tryk, Akihiro Iiyama, Hiroyuki Uchida
The electrocatalytic activity for the hydrogen oxidation reaction (HOR) in the presence of 1000 ppm of CO has been investigated on a series of binary Pt alloy catalysts Pt–M (M = Fe, Co, Ni), having two atomic layers of stabilized Pt skin (Pt2AL), supported on carbon black (Pt2AL–PtFe/C, Pt2AL–PtCo/C, and Pt2AL–PtNi/C) in 0.1 M HClO4 solution at 70 and 90 °C. It was found that Pt2AL–PtFe/C exhibited the highest CO-tolerant HOR activity (with respect to the area-specific activity js and the mass activity MA), followed by Pt2AL–PtCo/C and Pt2AL–PtNi/C. Such an order of the js values for the HOR with and without adsorbed CO can be correlated with density functional theory calculations, which have enabled us to propose a mechanism for the HOR on these surfaces. The apparent values of MA for the HOR on Pt2AL–PtFe/C at 20 mV vs RHE were 2–3 times larger than those for the conventional commercial catalyst c-Pt2Ru3/C over the whole CO coverage range from 0 to 0.7 at 70 and 90 °C. For an accelerated durability test simulating air exposure (2500 potential cycles between 0.02 and 0.95 V), the apparent js values for the CO-tolerant HOR on these Pt-skin catalysts were maintained completely, indicating that the dealloying of M components was virtually suppressed, whereas a significant reduction in js was observed for c-Pt2Ru3/C. A great mitigation of the particle agglomeration was also a highly attractive property of our catalysts in comparison with the commercial catalysts c-Pt/C and c-Pt2Ru3/C.