Authors: Natasa Vasiljevic | Vinicius Cruz San Martin | Alicja Szczepańska
Source: ECS Meeting Abstracts (article, 2024-11-22)
Field: Materials Science — Materials Chemistry

Electrodeposition of Ag-Au Alloys and Design of Nanoporous Gold with Controlled Porosity Due to its unique physicochemical, mechanical, and optical properties, Nanoporous gold (NPG) is of interest for various applications.[1-3] Its monolithic structure with the nanoscale size of ligaments and rich surface electrochemistry make the NPG materials unique for use in electrocatalysts, energy storage, sensors and plasmonics. The length scale of NPG porosity (ligaments &amp; open pores) and its effect on the properties is essential for such a broad range of applications. The porosity size can be controlled by parent alloy composition, dealloying (chemical, electrochemical) method, and the temperature of dealloying and annealing. Using the electrochemical surface processes to change and fine-tune the size, uniformity and hierarchy of the ligament network has been attracting attention as a possible tool for manipulating and designing new and improved NPG functionalities. [4, 5] We will present an all-electrochemical approach to creating NPG thin films with different sizes of porosity from Ag x Au 1-x alloys. The alloys of various compositions were electrodeposited at the constant potential from a thiosulfate-based solution by controlling the potential and concentration of Ag + and Au + ions.[6] The electrodeposited alloys' structural (SEM, AFM) and composition (XPS) characterisation was followed by the selective dissolution of Ag under electrochemical control. Pb monolayer underpotential deposition (UPD) was used to measure the surface area of as-created NPG structures. [7] The surface stress-driven surface alloying [8] taking place during this UPD process was exploited as an electrochemical tool to modify the NPG structure. Combining electrochemical and structural characterisation, we followed the evolution of porosity by controlling the range of the UPD potentials, scan rate and the number of cycles applied. References Biener, J., et al., Nanoporous Plasmonic Metamaterials. Advanced Materials, 2008. 20 (6): p. 1211-1217. Qiu, H.J., et al., Correlation of the structure and applications of dealloyed nanoporous metals in catalysis and energy conversion/storage. Nanoscale, 2015. 7 (2): p. 386-400. Weissmüller, J. and K. Sieradzki, Dealloyed nanoporous materials with interface-controlled behavior. MRS Bulletin, 2018. 43 (1): p. 14-19. Sharma, A., et al., Electrochemical annealing of nanoporous gold by application of cyclic potential sweeps. Nanotechnology, 2015. 26 (8): p. 085602. Dorofeeva, T.S., et al., Electrochemically Triggered Pore Expansion in Nanoporous Gold Thin Films. J. Phys. Chem. C, 2016. 120 (7): p. 4080-4086. McCurry, D.A., et al., All electrochemical fabrication of a platinized nanoporous Au thin-film catalyst. ACS Appl Mater Interfaces, 2011. 3 (11): p. 4459-68. Liu, Y., S. Bliznakov, and N. Dimitrov, Comprehensive Study of the Application of a Pb Underpotential Deposition-Assisted Method for Surface Area Measurement of Metallic Nanoporous Materials. J Phys Chem C, 2009. 113 : p. 12362–12372. Nutariya, J., et al., Surface alloying/dealloying in Pb/Au (111) system. ECS Transactions, 2010. 28 (25): p. 15-25. Vasiljevic, N. and A. Szczepanska, Surface Alloying During Pb Underpotential Deposition on Au(111). Journal of The Electrochemical Society, 2022. 169 (11): p. 112509 (1-8) Nanoporous ; Porosity ; Materials science ; Metallurgy ; Nanotechnology ; Composite material Nanoporous metals and alloys ; Electrodeposition and Electroless Coatings