Promotion of PtIr and Pt catalytic activity towards ammonia electrooxidation through the modification of Zn |
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Institution: | 1. National Institute of Technology, Tokyo College, Kunugida 1220-2, Hachiouji, Tokyo, Japan;2. Tokyo Institute of Technology, Nagatsuda 4259, Midori-ku, Yokohama, Kanagawa, Japan;3. Department of Applied Chemistry, Toyo University, 2100 Kujirai, Kawagoe, Saitama 350-8585, Japan |
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Abstract: | Zn is introduced into Pt and PtIr electrodes by applying potential cycles to their corresponding polycrystalline microdisc electrodes in a ZnCl2-containing ionic liquid bath. Scanning-electron microscopy and energy-dispersive X-ray microanalysis studies show that nanostructured PtIrZn and PtZn layers created on the microdisc electrodes contain approximately 5 wt% Zn. Cyclic voltammetric studies reveal that PtZn and PtIrZn are significantly more active towards electrochemical ammonia oxidation in alkaline media than virgin Pt and PtIr electrodes. The PtIrZn electrode demonstrates a low onset potential of 0.30 V vs RHE and a high exchange current density of 4.3 × 10? 8 A cm? 2, which is favorably comparable to state-of-the-art electrocatalyts for the same reaction. The catalytic activity promotion by the Zn modification may be related to the inhibition of the hydrogen electrochemistry. PtIrZn appears therefore to be a very promising anode catalyst for direct ammonia fuel cells and ammonia electrolysis. |
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