Publication
Title
Aqueous citrato-oxovanadate(IV) precursor solutions for VO2 : synthesis, spectroscopic investigation and thermal analysis
Author
Abstract
An aqueous precursor solution, containing citrato-VO2+ complexes, is synthesized for the formation of monoclinic VO2. With regard to the decomposition of the VO2+ complexes towards vanadium oxide formation, it is important to gain insights into the chemical structure and transformations of the precursor during synthesis and thermal treatment. Hence, the conversion of the cyclic [V4O12](4-) ion to the VO2+ ion in aqueous solution, using oxalic acid as an acidifier and a reducing agent, is studied by (51)Vanadium nuclear magnetic resonance spectroscopy. The citrate complexation of this VO2+ ion and the differentiation between a solution containing citrato-oxalato-VO2+ and citrato-VO2+ complexes are studied by electron paramagnetic resonance and Fourier transform infra-red spectroscopy. In both solutions, the VO2+ containing complex is mononuclear and has a distorted octahedral geometry with a fourfold R-CO2- ligation at the equatorial positions and likely a fifth R-CO2- ligation at the axial position. Small differences in the thermal decomposition pathway between the gel containing citrato-oxalato-VO2+ complexes and the oxalate-free gel containing citrato-VO2+ complexes are observed between 150 and 200 degrees C in air and are assigned to the presence of (NH4)(2)C2O4 in the citrato-oxalato-VO2+ solution. Both precursor solutions are successfully used for the formation of crystalline vanadium oxide nanostructures on SiO2, after thermal annealing at 500 degrees C in a 0.1% O-2 atmosphere. However, the citrato-oxalato-VO2+ and the oxalate-free citrato-VO2+ solution result in the formation of monoclinic V6O13 and monoclinic VO2, respectively.
Language
English
Source (journal)
Journal of the Chemical Society: Dalton transactions. - London
Publication
London : 2014
ISSN
0300-9246
1477-9226
1472-7773
Volume/pages
43:33(2014), p. 12614-12623
ISI
000340353100020
Full text (Publishers DOI)
UAntwerpen
Faculty/Department
Research group
Publication type
Subject
Affiliation
Publications with a UAntwerp address
External links
Web of Science
Record
Identification
Creation 09.10.2014
Last edited 29.04.2017
To cite this reference