Shape-Tailored Porous Gold Nanowires: From Nano Barbells to Nano Step-Cones

Abstract

Step-like porous gold nanowires of different shapes and diameters have been prepared by sequentially depositing alloy segments composed of different gold/silver ratios and de-alloying the silver component. For example, step-cone and nano-barbell porous gold nanowires were generated by a membrane-templated sequential deposition of gold-silver alloy segments from plating solutions of respectively decreasing or alternating gold/silver composition ratios. Alloy segments of different gold/silver ratios, prepared by using different plating potentials, also lead to multistep nanowires. In addition to step-like nanowires, we describe the preparation of cone- and bone-shaped porous nanowires from alloy nanowires of longitudinally changing compositions, generated via deposition from a flowing plating solution of a continuously changing composition. Such customization of the porous gold nanostructure is attributed to the chemical removal of silver and the different extents of gold reordering from alloy segments of different compositions. The latter leads to porous gold segments of smaller diameters from silver-rich alloy segments. The new "nanomachining" concept is versatile and could be extended to nanowires of diverse shapes with a variety of properties, generating an attractive assortment of nano-hardware.

Direct Electrodeposition of Porous Gold Nanowire Arrays for Biosensing Applications

“…[21,22] However, there is no report on the direct electrodeposition of porous nanowires. An explanation of the growth mechanism of porous nanowires must remain speculative.…”

Nanoporous Gold Electrodes and Their Applications in Analytical Chemistry

“…nanosized pores [52][53][54][55][56]. For example, Ji and Searson have used this approach to prepare nanoporous gold nanowires and films [53,54].…”

“…For example, Ji and Searson have used this approach to prepare nanoporous gold nanowires and films [53,54]. Loacharoensuk and coworkers took this one step further and demonstrated the fabrication of "shapetailored porous gold nanowires" via sequential electrodeposition of Au/Ag solutions of different composition in the pores of a gold-coated alumina oxide nanoporous membrane [55]. Yoo and Park fabricated porous gold vertical nanorods arrays and decorated them with platinum [56].…”

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

“…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.…”