《研究生组会报告》由会员分享，可在线阅读，更多相关《研究生组会报告（31页珍藏版）》请在金锄头文库上搜索。
1、组会报告,2012.12.03 刘欣美,本周工作,Cu2O microcrystals: a versatile class of self-templates for the synthesis of porous Au nanocages with various morphologies.常见的能谱光谱,Template-free,Mainly contains ultrasonication, spray drying or pyrolysis, laser pyrolysis,etc. The features of this method are simplicity of ope
2、ration, cost effectiveness and lack of elaborate equipment. Disadvantages difficulties in controlling the size and shape of hollow structures.,Template-assistant,Template-assistant method is one of the most controllable approaches for the synthesis of hollow nanostructures Traditional template-based
3、 routes involve the growth of a shell of designed materials on various removable templates.form coreshell composites and subsequently remove the template portions by calcinations or selective etching,generating hollow structures, whose inner structure is largely determined by the size and shape of t
4、he templates.,Self-templating methods,Under these conditions, the newly developed self-templating methods are more attractive. These strategies eliminate the need for heterogeneous growth,making them more convenient to control the sizes and the shapesof the interior void of the products 1.Ostwald ri
5、pening process 2. Kirkendall effect 3. galvanic replacement,Abstract,Design and synthesis of Au nanocages is one of the basic interests in the fabrication of nanoscale structures due to their attractive potentials in catalysis, medical science and so on. In most cases, spherical or cubic Au nanocage
6、s were fabricated using silica nanoparticles or Ag nanocubes as templates. In this article, another kind of versatile template, Cu2O microcrystals, has been employed to synthesize Au nanocages with various morphologies, such as cube, sphere, octahedron, truncated octahedron, cuboctahedron and concav
7、e cube morphologies.,When the Cu2O microcrystals possess only one type of exposed planes, Au nanoparticles (NPs) are deposited homogeneously on the supports, etching out Cu2O portions in the as-prepared nanocomposites, with porous Au nanocages produced. However, if the Cu2O microcrystals have two ki
8、nds of exposed planes, such as (111) and (100), selective deposition of Au NPs was observed. Based on this phenomenon, cuboctahedral and truncated octahedral Au nanoframes were synthesized.The catalytic activity of cubic Au nanocages in the reduction of 4-nitrophenol by sodium borohydride is much hi
9、gher than that of reported spongy Au nanocrystals,Synthesis of Cu2O crystals,1.Cu2O cube1.0 mL of 0.1 M CuCl2and 1.0 mL of 0.2 M NaOH were introduced into 50 mL distilled water under magnetic stirring.1.0 mL of 0.1 ML-ascorbic acid solution (containing 0.1 mL of 0.2 M NaOH) was added.This mixture wa
10、s kept at room temperature for 20 min under stirring.,Cu2O octahedron,The procedures for the synthesis of octahedral Cu2O crystals were similar to those of for the synthesis of cubic Cu2O crystals,except that hydrazine hydrate(2.0 mL, 1.0 M) was used instead of the ascorbic acid solution.,Cu2O trunc
11、ated octahedron and cuboctahedron,1.5 gPVP and 1.0 mL of 0.7 M copper sulfate were introduced into a round-bottomed glass flask containing 17 mL of distilled water. Then 1.0 mL of 0.74 M sodium citrate solution and 1.0 mL of 1.2 M anhydrous sodium carbonate solution was added. After being stirred fo
12、ranother 10 min, 1.0 mL of 1.4 M glucose solution was injected into the mixture. the mixture was kept at a temperature of 80C for 2 h.,Cu2O spherical particles,2.0 mM of copper acetate and 1.0 mM of poly(vinyl-pyrrolidone) were dissolved in 25 mL ofN,N-dimethylforma-mide. Then, the mixture was kept
13、at 90C for 5 min after the addition of NaBH4.,Cu2O concave cube,1.0 mL of 0.1 M CuCl2 and 0.1 mL of 0.7 M sodium citrate were introduced into 50 mL distilled water under magnetic stirring, then 0.1 mL of 0.2 M NaOH solution was added slowly. After being stirred for another 15 min, 0.2 mL of 1.4 M gl
14、ucose solution was injected. Finally, the mixture was transfer into a 50 mL round-bottomed glass flask and was placed in a microwave refluxing system,Synthesis of Cu2OAu nanocomposites,1.The as-prepared Cu2O crystals with different shapes were dispersed into deionized water with a concentration 174
15、mg mL-1. 2.In a typical synthesis of cubic Cu2OAu nanocomposites, 0.20 mL of HAuCl4(0.50 mM)was injected into 0.10 mL cubic Cu2O colloid solution under vigorous stirring. 3.In order to control the size and density of the Au NPson the Cu2O crystal surfaces, different concentrations of HAuCl4solution,
16、 such as 1.25 and 2.50 mM, were injected into the Cu2Ocolloid solutions respectively under the same conditions.4.Other shaped Cu2OAu coreshell nanocomposites were prepared in the similar way. 5.In all experimental procedures, the volume of HAuCl4solution injected was 0.20 mL unless stated otherwise.,Au nanocages,Different shaped Au nanocages were prepared by etching corresponding coreshell nanocomposites in hydrochloric acid(1 M) for 10 min. The precipitates were harvested by centrifuging, and then were washed with distilled water and absolute ethanol several times.,
