Growth of Nanobipyramid by Using Large Sized Au Decahedra as Seeds

Abstract

Au nanobipyramids (NBPs) are important nanostructures which attract much attention due to their unique structure, optical, and catalytic properties. The controlled synthesis of Au NBPs and corresponding mechanistic study are highly desirable for both fundamental research and practical applications. Herein, we demonstrate a strategy that large sized Au decahedra with well-defined shape act as seeds for growing NBPs. Furthermore, through using different sized decahedra seeds with edge from 25 to 49 nm, various sized NBPs can be easily prepared (longitudinal length from 110 to 210 nm; transverse length from 36 to 70 nm). Our study provides hard evidence for the growth of NBPs that they surely stem from the overgrowth on penta-twinned decahedra. Because these used large size seeds have well-defined shape and structure, the growth of the NBPs can be easily determined. Results show that the formation of NBPs is primarily determined by the molar ratio of Au(3+) and Au seeds (MRAA). MRAA less than 4 only causes size enhancement and no significant shape change. In cases of MRAA higher than 4 and lower than 8, quasi-nanorods are produced. When MRAA range from 8 to 10, NBPs form and the yield is higher than 90%. The effect of reaction time and temperature also are vital to the growth of NBPs. These prepared NBPs are found to exhibit excellent surface enhanced Raman scattering (SERS) performance because of many present hotspots, edges, steps, and tips on their surfaces.

Size and nanocrystallinity controlled gold nanocrystals: synthesis, electronic and mechanical properties

“…5,6,8,9 Chemical syntheses are nowadays available to rationalize the production of metal NPs with controllable size and shape. [10][11][12][13][14][15][16][17][18][19][20][21] One of the most efficient methodologies for well-controlled chemical synthesis is the seeded-growth method, which allows fine control of the gold NP growth on already-prepared seeds.…”

“…11,12,17 Nonetheless, one parameter that is not yet well controlled is their nanocrystallinity, i.e. the amount of crystal defects inside the NP.…”

Facile Growth of High-Yield Gold Nanobipyramids Induced by Chloroplatinic Acid for High Refractive Index Sensing Properties

“…For example, Huang et al . produced Au NBPs using an overgrowth process by employing large sized Au decahedra as the seeds1415. However, this synthetic process involved a high temperature and complex organic agents, making it still difficult to prepare.…”

Rational selection of halide ions for synthesizing highly active Au@Pd nanobipyramids

“…2C-G). 47 The HRTEM images show a 0.225 nm interplanar spacing, which is attributed to the Pd(111) plane (Fig. 2D-F).…”

“…47,65 In a typical preparation, 0.5 mL PDDA was added to 20 mL DEG under magnetic stirring (500 rpm), and then 20 mL HAuCl 4 (0.48 M) aqueous solution was introduced. Aer a yellow homogeneous solution had formed, 4 mL DEG solution containing 12 mg AgNO 3 was added, and then the mixture was stirred for another 3 min.…”