Controlled Synthesis of Gold Nanobelts and Nanocombs in Aqueous Mixed Surfactant Solutions

Abstract

Well-defined gold nanobelts as well as unique gold nanocombs made of nanobelts were readily synthesized by the reduction of HAuCl4 with ascorbic acid in aqueous mixed solutions of the cationic surfactant cetyltrimethylammonium bromide (CTAB) and the anionic surfactant sodium dodecylsulfonate (SDSn). Single-crystalline gold nanobelts grown along the <110> and <211> directions were prepared in mixed CTAB-SDSn solutions at 4 and 27 degrees C, respectively. Furthermore, single-crystalline gold nanocombs consisting of a <110>-oriented stem nanobelt and numerous <211>-oriented nanobelts grown perpendicularly on one side of the stem were fabricated by a two-step process with temperature changing from 4 to 27 degrees C. It was proposed that the mixed cationic-anionic surfactants exerted a subtle control on the growth of gold nanocrystals in solution due to the cooperative effect of mixed surfactants. This synthetic strategy may open a new route for the mild fabrication and hierarchical assembly of metal nanobelts in solution. The obtained gold nanobelts showed good electrocatalytic activity toward the oxidation of methanol in alkaline solution; in particular, the electrode modified with the nanobelts obtained at 27 degrees C exhibited an electrocatalytic activity considerably higher than normal polycrystalline gold electrode. Moreover, the gold nanobelts were used as the surface-enhanced Raman scattering (SERS) substrate for detecting the enhanced Raman spectra of p-aminothiophenol (PATP) molecules, and the gold nanobelts obtained at 4 degrees C exhibited an unusual larger enhancement of the b2 modes relative to the a1 modes for the adsorbed PATP molecules.

Reactivity of Gold Nanobelts with Unique {110} Facets

“…Gold is generally considered as an inert metal toward methanol oxidation, [30][31][32] but an advantage of gold as catalyst is that the poisoning intermediates are not formed, and recent studies [6,7,[9][10][11][30][31][32] discovered that Au could exhibit an unusually high electrocatalytic activity. The electrocatalytic activity was attributed to the size and shape and the initial results showed that gold could be a promising candidate for the electrocatalytic oxidation of methanol.…”

“…Although the size effect has been extensively studied, [8] the influence of surface structure of nanostrutures as electrocatalysts is still in the focus of investigations. [9][10][11] Different crystal surfaces or directions may exhibit different physical and chemical properties due to the anisotropic properties of crystals. For example, the {111}, {110} and {100} surfaces of a face-centred cubic (fcc) metal, such as gold, show differences not only in the surface atom density, but also in the electronic structures and the resulting chemical reactivity.…”

Solution-Phase Synthesis of Branched Metallic Nanoparticles for Plasmonic Applications

“…Au nanoplates were sandwiched by the protecting agent and then grew into a network structure 47,48 . This edge formation can be explained by the limited supply of the precursor only at the edges.…”

Electrochemical sensor systems based on one dimensional (1D) nanostructures for analysis of bioaffinity interactions

“…Однако матричный синтез имеет ряд недостатков, в частности, необходимость удаления матрицы, сложность масштабирования получения нанопроводов для последующего коммерческого использования [6]. В связи с этим активно развиваются химические методы синтеза одномерных наноструктур на основе металлов и их производных [10,11]. Одномерные наноструктуры на поверхности электродов получают, используя адсорбцию наночастиц на поверхности одномерных структур [12,13].…”