Influence of Processing Conditions on Structures of 3D Ordered Macroporous Metals Prepared by Colloidal Crystal Templating
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- 作者：Hongwei Yan ; Christopher F. Blanford ; Justin C. Lytle ; C. Barry Carter ; William H. Smyrl ; and Andreas Stein
- 刊名：Chemistry of Materials
- 出版年：2001
- 出版时间：November 2001
- 年：2001
- 卷：13
- 期：11
- 页码：4314 - 4321
- 全文大小：383K
- 年卷期：v.13,no.11(November 2001)
- ISSN：1520-5002
文摘
This paper presents general methods of preparing three-dimensionally ordered macroporous(3DOM) metals or alloys via templated precipitation and subsequent chemical conversionof metal salts (acetates, oxalates) within colloidal crystals of poly(methyl methacrylate)(PMMA) or polystyrene (PS) spheres. Three approaches are given to prepare 3DOM metallicNi, Co, and Fe and the alloy Ni1-xCox: (1) calcination of the metal oxalate/template compositein a nitrogen atmosphere, (2) formation of a 3DOM metal oxide followed by reduction inhydrogen, and (3) direct reduction of the metal oxalate/template composite in hydrogen. The3DOM products obtained by these routes differ in size of the grains that compose the wallskeletons, in surface areas, and in compositions. Method 1 leads to very small grains andhigh surface areas but incomplete removal of carbon with graphitic layers surrounding metalgrains. Method 2, as a two-step process, leads to relatively large metal grains, smaller surfaceareas, and carbon-free products. Method 3 strikes a compromise in these properties, withintermediate surface areas and small (<2%) amounts of remaining carbon. This paperpresents synthetic details, discusses effects of the template choice (PMMA vs PS), andcompares structural features of the macroporous metals and alloys, using the results of XRD,TGA, SEM, TEM, nitrogen adsorption data, and chemical analysis.