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Molecules 2018, 23(7), 1502;

One-Dimension Diffusion Preparation of Concentration-Gradient Fe2O3/SiO2 Aerogel

Shanghai Key Laboratory of Special Artificial Microstructure Materials and Technology, School of Physics Science and Engineering, Tongji University, Shanghai 200092, China
Author to whom correspondence should be addressed.
Received: 27 May 2018 / Revised: 16 June 2018 / Accepted: 18 June 2018 / Published: 21 June 2018
(This article belongs to the Special Issue Chemistry of Aerogels and Their Applications)
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Concentration-gradient Fe2O3/SiO2 aerogels were prepared by placing an MTMS (methyltrimethoxysilane)-derived SiO2 aerogel on an iron gauze with an HCl atmosphere via one-dimensional diffusion, ammonia-atmosphere fixing, supercritical fluid drying and thermal treatment. The energy dispersive spectra show that the Fe/Si molar ratios change gradually from 2.14% to 18.48% with a height of 40 mm. Pore-size distribution results show that the average pore size of the sample decreases from 15.8 nm to 3.1 nm after diffusion. This corresponds well with TEM results, indicating a pore-filling effect of the Fe compound. In order to precisely control the gradient, diffusion kinetics are further studied by analyzing the influence of time and position on the concentration of the wet gel. At last, it is found that the diffusion process could be fitted well with the one-dimensional model of Fick’s second law, demonstrating the feasibility of the precise design and control of the concentration gradient. View Full-Text
Keywords: Fe2O3/SiO2 aerogel; concentration gradient; nanocomposites; 1d diffusion Fe2O3/SiO2 aerogel; concentration gradient; nanocomposites; 1d diffusion

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This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited (CC BY 4.0).

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Zhang, T.; Wang, H.; Zhou, B.; Ji, X.; Wang, H.; Du, A. One-Dimension Diffusion Preparation of Concentration-Gradient Fe2O3/SiO2 Aerogel. Molecules 2018, 23, 1502.

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