Dealloying to Nanoporous Silver and Its Implementation as a Template Material for Construction of Nanotubular Mesoporous Bimetallic Nanostructures

Abstract

Nanoporous silver (NPS) is fabricated by selectively dissolving Al from AgAl alloys in corrosive electrolytes at room temperature. Electron spectroscopy characterizations demonstrate that the NaOH electrolyte is beneficial to the formation of a three-dimensional bicontinuous porous nanostructure with uniform and tunable pore and ligament dimensions of a few tens of nanometers, while processing in HCl electrolyte easily lead to coarsened porous nanostructures. The high-surface-area Ag nanostructures are demonstrated as novel effective template materials to the construction of nanotubular mesoporous Pt/Ag and Pd/Ag alloy structures, which are realized via room temperature galvanic replacement reactions with H(2)PtCl(6) and K(2)PdCl(4) solutions by adding a high concentration of Cl(-) ions as a coordinating agent. Electrochemical measurements indicate that the resulting hollow and porous bimetallic nanostructures show enhanced electrocatalytic activities and CO-tolerance with better durability toward methanol and formic acid oxidation due to alloying with Ag.

Using corrosion to fabricate various nanoporous metal structures

“…Besides the precursor composition, dealloying conditions such as dealloying time, temperature and solution, also have great effects on the microstructure of the nanoporous metals [19,[60][61][62][63][64]. For the dealloying time, in order to obtain complete 3D nanoporous structure, the dealloying time should be long enough to penetrate the entire precursor.…”

“…After the Pt shell was smoothed by annealing (300°C for 30 min), the np-Au core was removed in aqueous gold etchant (KI: 10 wt.%, I 2 : 5 wt.%), and the nanotubular Pt was obtained [108]. Following the np-Au template, np-Cu and np-Ag templates have also been successfully applied [62,109]. Based on the active properties of Cu and Ag, the galvanic replacement reaction between Pt (Pd) and Cu (Ag) would etch away Cu (Ag) within the ligaments and form a nanotubular Pt-or Pd-based alloy structure (Fig.…”

Sponge-like carbon thin films: The dealloying concept applied to copper/carbon nanocomposite

“…It should be noted that the means of control of the pore characteristics depend on both the strategy used to create the porosity within the material and the considered material itself. For example, to create nanoporous metals, ''dealloying'' is the most popular method which has been developed so far [9,11,12,16,19,45,[49][50][51][52][53][54][55][56]. This approach consists in removing one of two alloyed metals using a selective corrosion process [54,57].…”

“…The high specific surface area of this kind of material confers them exceptional properties such as super-hydrophobicity [1,2], enhanced catalysis activity [3][4][5][6], and very selective filtering ability [7,8]. Various materials were used to synthesize nanoporous structures including metals (e.g., Au [6,[9][10][11][12][13][14], Pt [15][16][17][18], and Ag [19,20]), oxides (e.g., TiO 2 [21][22][23] and SiO 2 [24,25]) and carbon [26][27][28][29][30][31][32][33][34][35][36]. In general, the material forming the skeleton of the nanoporous structure is selected according to the aimed application.…”

Dealloying Ag–Al Alloy to Prepare Nanoporous Silver as a Substrate for Surface‐Enhanced Raman Scattering: Effects of Structural Evolution and Surface Modification

“…Nanoporous metal materials have been widely used in catalysis, sensing/biosensing, and so forth due to their large specific surface area, catalytic activity, and excellent thermal and electrical conductivity. [13][14][15][16][17][18] Recently, nanoporous metals (Au and Cu), obtained by dealloying, and their composites (AuAg and CuAg), obtained by dealloying and then surface modification, have been exploited as active SERS substrates and tunable SERS enhancements have been achieved by adjusting the pore/ligament size or surface modification with other metals. [19][20][21][22][23] Due to the low price of Ag (compared with Au), large signal enhancement, and good stability (compared with Cu), nanoporous silver (NPS) as a SERS substrate candidate would hold great promise.…”