Controlled phase synthesis of VO in differing oxidation states using a simplified formic acid process, quantified with a new generalized index designed for use with public domain material process information
An environmentally benign approach for the synthesis of vanadium pentoxide (V 2 O 5 ), vanadium dioxide (VO 2 ) and divanadium trioxide (V 2 O 3 ) sols, potentially suitable for device applications, is reported. Synthesis of vanadium oxides is challenging because of their tendency to exist in multip...
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| Published in | Green chemistry : an international journal and green chemistry resource : GC Vol. 23; no. 2; pp. 82 - 8211 |
|---|---|
| Main Authors | , , , , , , |
| Format | Journal Article |
| Published |
18.10.2021
|
| Online Access | Get full text |
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| Summary: | An environmentally benign approach for the synthesis of vanadium pentoxide (V
2
O
5
), vanadium dioxide (VO
2
) and divanadium trioxide (V
2
O
3
) sols, potentially suitable for device applications, is reported. Synthesis of vanadium oxides is challenging because of their tendency to exist in multiple (+2 to +5) and mixed oxidation states. However, a simple approach has been developed successfully using formic acid and citric acid, as a viable scalable and sustainable process. Crystalline oxides of vanadium were obtained after annealing of sols under controlled temperature and atmospheric conditions. Chemical composition of the synthesized V
2
O
3
was inferred from Raman spectroscopy; VO
2
did not show any Raman peak at room temperature except a feature at 226 cm
−1
, while no significant information was obtained from the Raman spectra of V
2
O
3
. When excited at 405 nm, V
2
O
5
and VO
2
exhibit photoluminescence at 558 nm and 467 nm, respectively, while V
2
O
3
shows radiative recombination at 446 and 473 nm. Particles of V
m
O
n
exhibit broad absorption bands as predicted by absorption spectroscopy. Sols of V
2
O
5
and VO
2
were found to be stable for more than six months, while V
2
O
3
shows instability in air. A free-standing V
m
O
n
solution was used as an active layer in metal insulator metal (MIM) structures to explore possible device applications. To evaluate the suitability of this process, a dimensionless composite index of greenness (
G
) of processes is proposed, based on commonly held metrics of the desirable characteristics of green processes. This index is amenable to derivation using restricted process information customarily available in the literature. The process is found to exhibit greenness indices of 0.744 and 0.585 for V
2
O
5
and VO
2
, respectively. Other published processes for the synthesis of these oxides are also quantified using our index.
This work reports a simplified low-cost environmentally benign synthetic process for the production of pure or nearly pure phase vanadium oxides in three different oxidation states, and quantifies the sustainability of the process with a green index. |
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| Bibliography: | 10.1039/d1gc02470a Electronic supplementary information (ESI) available. See DOI |
| ISSN: | 1463-9262 1463-9270 |
| DOI: | 10.1039/d1gc02470a |