Dealloying and Synthesis of Nanoporous Pt and Au from AgPt and AgAu Binary Alloys

• Main Author: Ganti Mahapatruni, Aditya
• Other Authors: Newman, Roger C.
• Language: en_ca
• Published: 2010
• Subjects: Dealloying; Nanoporous; AgAu; AgPt; Critical potential; 0542
• Online Access: http://hdl.handle.net/1807/25594

A study is presented on the synthesis and characterization of nanoporous AgPt and AgAu alloys after annealing and dealloying in 5% HClO4. Dealloying removes the less-noble atom from the alloy surface to produce nanoporous, highly-interconnected ligaments. Voltammetry of AgPt and AgAu shows the critical potential, Ec, at various potential scan rates. Potential hold current decay experiments on Ag-23Pt and Ag-23Au further show the intrinsic Ec to be 275 mV and 290 mV, respectively. Ec was governed by thermodynamic clustering in the alloys as opposed to dissolution-diffusion kinetic effects. EDX shows the starting 77Ag-23Pt material changes composition after dealloying to about 12Ag-88Pt. XRD indicates the presence of ordering in AgPt via a superlattice (100)-peak for a specific anneal treatment. EIS measurements done on as-annealed and dealloyed AgPt and AgAu samples show the onset of bulk porosity and show that capacitance increase is equal for both alloys at two different dealloying potentials.