On the Nature and Location of Nanoparticulate Iron Phases and Their Precursors Synthetized within a Sepiolite Matrix

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• 作者：Antonio Esteban-Cubillo ; Jos&eacute ; F. Marco ; Jos&eacute ; S. Moya ; Carlos Pecharromá ; n
• 刊名：Journal of Physical Chemistry C
• 出版年：2008
• 出版时间：February 28, 2008
• 年：2008
• 卷：112
• 期：8
• 页码：2864 - 2871
• 全文大小：726K
• 年卷期：v.112,no.8(February 28, 2008)
• ISSN：1932-7455

文摘

In this work, we report on the characterization by Mössbauer spectroscopy, X-ray diffraction, and transmissionelectron microscopy of nanoparticulate iron phases and their precursors synthesized by a wet chemical routewithin the framework of a silicate matrix (sepiolite). These results show that the nature and location of thedifferent iron species within the sepiolite structure are dependent on the conditions of the wet chemicalpreparation and, specifically, on the pH value of the acidic treatment to which the sepiolite powder wassubjected prior to the impregnation with the iron(III)-containing solution. A subsequent thermal treatment at500 C (2 h) of the iron-containing sepiolites in a reducing H₂/Ar atmosphere leads to the formation ofdifferent iron-reduced species. The nature of these reduced species is also dependent on the initial acidictreatment of the sepiolite. So, in the case of the iron-containing materials produced after treatment in strongacidic conditions of the original sepiolite, the reducing conditions bring about the formation of a significantamount of metallic iron nanoparticles. These metallic iron nanoparticles have been shown to be stronglyresistant to oxidation at high temperatures. In the case of milder acidic initial conditions, the reduced samplesdo not contain metallic iron particles but mainly nonstoichiometric Fe₃O₄ nanoparticles.