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Asynchronous Evolution of Nanoporous Silver on Dual-Phase Ag–Sn Alloys by Potentiostatic Dealloying in Hydrochloric Acid Solution

1
College of Materials Science and Engineering and Tech Institute for Advanced Materials, Nanjing Tech University, Nanjing 210009, China
2
State Key Lab of Advanced Metals and Materials, University of Science and Technology Beijing, Beijing 110083, China
3
State Key Laboratory of Metal Material for Marine Equipment and Application, Anshan 114021, China
4
School of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing 210094, China
*
Authors to whom correspondence should be addressed.
Nanomaterials 2019, 9(5), 743; https://doi.org/10.3390/nano9050743
Received: 26 April 2019 / Revised: 8 May 2019 / Accepted: 9 May 2019 / Published: 14 May 2019
PDF [2612 KB, uploaded 14 May 2019]

Abstract

Evolution behavior of the nanoporous architectures has been investigated via potentiostatic electrochemical dealloying of dual-phase AgxSn100x (x = 20, 30, 40 at.%) alloys, which consist of β-Sn and ε-Ag3Sn phases with different volume fractions in 1.2 M HCl solution. The results show that the open-circuit potentials and corrosion potentials of dual-phase Ag–Sn alloys are determined by the less noble β-Sn phases rather than chemical compositions of the Ag–Sn precursor alloys. The potentiodynamic polarization curves show that the anodic dissolution of Ag–Sn alloys is divided into two stages including the first preferential dissolution of β-Sn phases and secondary dealloying of ε-Ag3Sn phases, which is associated with the order of the nanoporous evolution. Nanoporous silver (NPS) can be fabricated by potentiostatic dealloying of dual-phase Ag–Sn alloys in HCl solution. The dealloying of two phases is asynchronous: The less noble β-Sn phases are preferentially etched to generate the larger pores, and then the more noble ε-Ag3Sn phases are dealloyed to form the finer nanoporous structure. The significant surface diffusion of Ag adatoms at the applied potential higher than the pitting potential of ε-Ag3Sn phases during the dealloying results in the coarsening of nanoporous ligaments with a time dependence of d(t) ∝ t0.1. The fractions and the difference in electrochemical stabilities of the β-Sn and ε-Ag3Sn phases in dual-phase AgxSn100x (x = 20, 30, 40 at.%) precursor alloys determines the final nanoporous structure.
Keywords: nanoporous silver; dual-phase Ag–Sn alloys; potentiostatic dealloying; surface diffusivity; potentiodynamic polarization behavior nanoporous silver; dual-phase Ag–Sn alloys; potentiostatic dealloying; surface diffusivity; potentiodynamic polarization behavior
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited (CC BY 4.0).
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Yang, Y.; Dan, Z.; Liang, Y.; Wang, Y.; Qin, F.; Chang, H. Asynchronous Evolution of Nanoporous Silver on Dual-Phase Ag–Sn Alloys by Potentiostatic Dealloying in Hydrochloric Acid Solution. Nanomaterials 2019, 9, 743.

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