Economical Synthesis of Vanadia Aerogels via Epoxide-Assisted Gelation of VOCl₃

Abstract

Herein is reported the first synthesis of vanadium oxide (vanadia) aerogels via epoxide-assisted gelation. Vanadia aerogels fabricated via epoxide-assisted gelation using VOCl3 and epichlorohydrin mimic those fabricated via the hydrolysis of vanadium oxytripropoxide while reducing cost per mole by a factor of 10, on par with silica gels synthesized from alkyl orthosilicates. Typical vanadia aerogels possess a macroporous nanoworm morphology, a density of 0.103 g/cm3, 96.9 % porosity, a specific surface area of 102 m2/g, and ~18 % reversible hydration capacity by mass. 1H and 13C NMR reveal that epoxide ring-opening does not proceed through epoxide protonation, as is the typical case with other transition metal oxide gels, but rather through Lewis-acid-catalyzed ring-opening. a multi-step gelation mechanism is proposed involving a fast initial VV oxide gelation, driven by H+ and Cl- consumption during epoxide ring-opening, followed by partial vanadia dissolution, VV → VIV reduction, and secondary gelation of low-valent VIV/V oxide.

Department(s)

Chemistry

Keywords and Phrases

Aerogels; Gels; Metals; Oxides; Silica gel; Transition metal compounds; Transition metals; Vanadium; Epichlorohydrin; Epoxide assisted gelations; Vanadia; Vanadium oxides; Vanadium oxytrichloride, Gelation; Aerogel; Epichlorohydrin; Epoxide-assisted gelation; Vanadia; Vanadium oxide; Vanadium oxytrichloride

International Standard Serial Number (ISSN)

0928-0707

Document Type

Article - Journal

Document Version

Citation

File Type

text

Language(s)

English

Rights

© 2015 Springer Verlag, All rights reserved.

Publication Date

01 Jan 2015

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