Preparation of Au-Ag Bimetals and Large-Size Porous Gold Nanostructured Materials

Xuewen Chen,Song Jiang

doi:10.1155/2021/4160735

Abstract

Gold, silver, and other precious metals are very important nonferrous metals and have been widely applied in fields such as electronics, medicine, metallurgy, pharmaceuticals, and transportation. Adjustable properties of precious metals are mainly attributed to controlled synthesis of precious metals by structure, size, composition, and morphology. Synthesis of binary metals focuses on coordination of physical and chemical properties of metal elements in components, with the aim to give full play to the advantages of the two metals. Gold (Au) and silver (Ag) have similar lattice constants, which provide important theoretical basis for obtaining the binary bimetallic nanostructure of the two metals by coreduction at room temperature. Ag–Au alloy was prepared at different molar ratios of Ag+/AuIII, and the bimetallic nanomaterials obtained had similar Ag/Au ratios to the molar ratio at reaction. This suggested that the bimetallic nanomaterials reacted completely, with the maximum average size in Ag90.1–Au9.9 and the minimum average size in Ag83.2–Au16.8 and Ag66.9–Au33.1. Due to the deficiency of conventional etching agents, the “regrowth etching” method was proposed in this study. Specifically, with AuI as the etching agent, the porous gold nanomaterials with the size of more than 300 nm were successfully prepared, achieving the regrowth etching effect and a good structural stability. According to the analysis based on the catalytic reduction reaction with p-nitrophenol, the properties of the large-size porous gold nanomaterials were related to the quantity and size of pores.

Highlights

IntroductionAccording to the definition adopted by the European Commission on October 18, 2011, “nanomaterial” means a natural, incidental, or manufactured material containing particles, in an unbound state or as an aggregate or as an agglomerate , where, for 50% or more of the particles in the number size distribution, one or more external dimensions is in the size range 1 nm–100 nm
In the chemical element components, the corresponding ratios of Ag to Au were 90.1 : 9.9, 83.2 : 16.8, and 66.9 : 33.1, respectively, which were close to the molar ratios at the reaction, indicating that the bimetallic nanomaterials obtained reacted completely
After the average particle size of bimetallic nanomaterials above was determined, it was found that bimetallic nanomaterials synthesized at different molar ratios had certain differences. e average size of Ag90.1–Au9.9, Ag83.2–Au16.8, and Ag66.9–Au33.1 is as shown in Figure 2, with the maximum average size in Ag90.1–Au9.9 and the minimum average size in Ag83.2–Au16.8 and Ag66.9–Au33.1

Summary

Introduction

According to the definition adopted by the European Commission on October 18, 2011, “nanomaterial” means a natural, incidental, or manufactured material containing particles, in an unbound state or as an aggregate or as an agglomerate , where, for 50% or more of the particles in the number size distribution, one or more external dimensions is in the size range 1 nm–100 nm. E European Commission suggests that basic particles of most nanomaterials are within this range, though materials beyond this range may have the characteristics of nanomaterials. E definition aims to make the standard clear: a low threshold of nanoparticles will cover up the nanoproperties of the whole material, and 50% is an appropriate threshold. Nanomaterials can be roughly divided into four categories: nanopowder, nanofiber, nanofilm, and nanoblock. The nanopowder features the longest development history and most mature technology and is the basis for the production of the other three

Methods

Results

Discussion

Conclusion