Preparation of mesoporous silica thin films at low temperature: a comparison of mild structure consolidation and templat
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ORIGINAL PAPER: FUNCTIONAL COATINGS, THIN FILMS AND MEMBRANES ( I N CL U D I N G D E P O S I T I O N T E C H N I Q U E S )
Preparation of mesoporous silica thin films at low temperature: a comparison of mild structure consolidation and template extraction procedures Gustavo Giménez1 Gabriel Ybarra1 Galo J. A. A. Soler-Illia ●
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Received: 24 June 2020 / Accepted: 31 August 2020 © Springer Science+Business Media, LLC, part of Springer Nature 2020
Abstract Mesoporous thin films (MTFs) displaying high surface area and controlled porosity constitute interesting materials for a plethora of applications in optics and electronics. A critical aspect in MTF processing is template removal that usually consists in thermal treatment at 350 °C, which consolidates the oxide film but might change the pore features. In addition, the use of such high temperature must be avoided when organic functionalities are to be preserved, or in the case of film deposition on polymeric substrates. Here we present and compare five different methods to consolidate silica MTF (SMTF) in mild conditions, at a maximum processing temperature of 130 °C. Conditions, such as duration of the thermal treatment, vacuum conditions, exposure to acidic and alkaline media, were systematically explored and the resulting films were analyzed by optical microscopy, focused ion beam, scanning electron microscopy, ellipsometry, and infrared spectroscopy. The optimized conditions leading to accessible mesopores and a stable oxide structure that can be used as a mesoporous perm-selective electrode are discussed. Graphical Abstract
Keywords
Mesoporous thin films Soft processing Sol–gel condensation Template extraction ●
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Supplementary information The online version of this article (https:// doi.org/10.1007/s10971-020-05410-z) contains supplementary material, which is available to authorized users. * Galo J. A. A. Soler-Illia [email protected] 1
INTI-Micro y Nanotecnologías, Instituto Nacional de Tecnología Industrial, Av. Gral. Paz 5445, San Martín, Buenos Aires, Argentina
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Instituto de Nanosistemas, Universidad Nacional de San Martín, CONICET, Av. 25 de Mayo 1021, San Martín, Buenos Aires, Argentina
Journal of Sol-Gel Science and Technology
Highlights ● Soft template extraction methods from mesoporous silica thin films onto Si and Au were compared. ● These low-T treatments permit to extract ionic and non-ionic surfactants, keeping film integrity. ● A complete analysis on template extraction, film adhesion, and mesopore size is provided. ● Optimized 130 °C treatment followed by vacuum leads to robust frameworks with accessible mesopores. ● Mesoporous electrodes can be used for more than 90 consecutive electrochemical cycles in aqueous solutions.
1 Introduction Mesoporous thin films (MTFs) have attracted the interest of the scientific community in the last two decades, due to their multiple applications in sensors, (photo)catalysts, molecular sieves, etc. [1] These materials are synthesized by the combination of sol–gel
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