Surface area and pore size characteristics of nanoporous gold subjected to thermal, mechanical, or surface modification studied using gas adsorption isotherms, cyclic voltammetry, thermogravimetric analysis, and scanning electron microscopy.

Journal of Materials Chemistry Pub Date : 2012-01-01 Epub Date: 2012-02-27 DOI:10.1039/C2JM16633J
Yih Horng Tan, Jason A Davis, Kohki Fujikawa, N Vijaya Ganesh, Alexei V Demchenko, Keith J Stine
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引用次数: 215

Abstract

Nitrogen adsorption/desorption isotherms are used to investigate the Brunauer, Emmett, and Teller (BET) surface area and Barrett-Joyner-Halenda (BJH) pore size distribution of physically modified, thermally annealed, and octadecanethiol functionalized np-Au monoliths. We present the full adsorption-desorption isotherms for N(2) gas on np-Au, and observe type IV isotherms and type H1 hysteresis loops. The evolution of the np-Au under various thermal annealing treatments was examined using scanning electron microscopy (SEM). The images of both the exterior and interior of the thermally annealed np-Au show that the porosity of all free standing np-Au structures decreases as the heat treatment temperature increases. The modification of the np-Au surface with a self-assembled monolayer (SAM) of C(18)-SH (coverage of 2.94 × 10(14) molecules cm(-2) based from the decomposition of the C(18)-SH using thermogravimetric analysis (TGA)), was found to reduce the strength of the interaction of nitrogen gas with the np-Au surface, as reflected by a decrease in the 'C' parameter of the BET equation. From cyclic voltammetry studies, we found that the surface area of the np-Au monoliths annealed at elevated temperatures followed the same trend with annealing temperature as found in the BET surface area study and SEM morphology characterization. The study highlights the ability to control free-standing nanoporous gold monoliths with high surface area, and well-defined, tunable pore morphology.

采用气体吸附等温线、循环伏安法、热重分析法和扫描电子显微镜对纳米孔金进行热、机械或表面改性的表面积和孔径特征进行了研究。
氮气吸附/解吸等温线用于研究物理修饰、热退火和十八硫醇功能化的np-Au整体体的Brunauer, Emmett, and Teller (BET)表面积和Barrett-Joyner-Halenda (BJH)孔径分布。我们给出了N(2)气体在np-Au上的全吸附-解吸等温线,并观察到IV型等温线和H1型滞回线。利用扫描电子显微镜(SEM)研究了不同热处理条件下np-Au的演化过程。热退火后的np-Au的内部和外部图像表明,随着热处理温度的升高,所有独立的np-Au结构的孔隙率都减小。利用热重分析(TGA)对C(18)-SH进行分解,发现用C(18)-SH自组装单层(SAM)(覆盖面积为2.94 × 10(14)分子cm(-2))修饰np-Au表面,可以降低氮气与np-Au表面的相互作用强度,这反映在BET方程的“C”参数的降低上。从循环伏安法研究中,我们发现在高温下退火的np-Au单体的表面积与在BET表面积研究和SEM形貌表征中发现的趋势相同。该研究强调了控制具有高表面积、定义明确、可调孔隙形态的独立纳米孔金单体的能力。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
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来源期刊
Journal of Materials Chemistry
Journal of Materials Chemistry 工程技术-材料科学:综合
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1.5 months
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