Abstract
Abstract
V
O
2
is well known for its reversible transition between two phases with tetragonal rutile and monoclinic structure. In a previous theoretical study (Stahl and Bredow 2022 ChemPhysChem
23 e202200131) we showed that the adsorption energy of CO is different on surfaces of the two Mo-stabilized polymorphs. This can be exploited to promote catalytic reactions by removing CO from the catalyst surface. As proof-of-principle, we investigated the hydrogenation reaction of
CO
2
. For this purpose, the adsorption energies of
CO
2
and possible intermediates and products
H
2
O
, HCOOH,
H
2
C
O
and CO were calculated. Significant differences were found for the reaction energies of the hydrogenation of
CO
2
to formic acid and formaldehyde on the two polymorphs. This shows that it is in principle possible to alter the reaction thermodynamics by applying reaction conditions which stabilize a particular polymorph. In order to investigate the influence of the polymorph on kinetic properties, the reactions barriers of a step-wise reaction of
C
O
2
+
2
H
2
→
H
2
C
O
+
H
2
O
was calculated using the nudged elastic band method.
V
O
2
was found to reduce the reaction barriers compared to the gas phase. Additionally, the minimum energy path of the bulk phase transition of undoped
V
O
2
was calculated using the distinguished reaction coordinate method. A catalytic cycle exploiting the phase transition is proposed based on the theoretical results.
Subject
Condensed Matter Physics,General Materials Science