Volume 26 Issue 7 - May 23, 2014 PDF
Chronopotentiometric Investigation of the Formation of Nanoporous Bimetallic Pd-Ag by Galvanic Replacement of Nanoporous Ag with Pd
Wan-Chi Lo, Yi-Ting Hsieh, I-Wen Sun*
Department of Chemistry, National Cheng-Kung University
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The formation of nanoporous palladium-silver (NPPS) structure through galvanic replacement reaction (GRR) of nanoporous silver (NPS) and palladium (II) nitrate is monitored by chronopotentiometry. During the GRR, the potential of the NPS varied with time from the formal potential of the Ag(I)/Ag couple toward that of the Pd(II)/Pd couple and approaches a “steady-state” value. The potential measurement offers a facile real-time monitoring of the GRR. Further, the potential value can be used as an indication of the Pd content in the NPPS; a more positive potential implies a higher Pd content. Prolonging reaction time results in no significant change in the NPPS composition once the steady-state value is reached, and thus, the steady-state can be used as a reference for the completion of the GRR. Not all the Ag can be replaced by Pd so that bimetallic NPPS are obtained. Effects of reaction time, temperature, and Pd (II) concentration on the Pd content and ligament size of the NPPS are studied. The NPPS structures are polycrystalline in nature and show superior electrocatalytic activity than pure Ag and Pd for electrooxidation of hydrazine and ethanol, respectively.
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