Paper
NJC
boundary conditions.39–41 The effect of the exchange–correlation Conflicts of interest
(XC) potential was explored by generalized gradient approxi-
mation with the PW91 functional.42 Kohm–Sham orbitals were
expanded in a plane waves basis set to a kinetic energy cut-off of
50 Ry for all structures. A vacuum layer of 15 Å was used in the
slab models to avoid interactions between the periodic images
perpendicular to the surface. Vibrational modes were obtained
from calculations of phonons that are based on the harmonic
approximation within the Density Functional Perturbation
Theory (DFPT) at point q, G.43 For more details regarding both
theoretical methodology and catalyst structural characterization,
see the ESI.†
The authors declare no conflict of interest.
Acknowledgements
The authors acknowledge the financial support from FAPEMIG,
´
CNPq and Rede Mineira de Quımica. This study was also
˜
financed in part by the Coordenaçao de Aperfeiçoamento de
´
Pessoal de Nıvel Superior – Brasil (CAPES) – Finance Code 001.
The DICAP/INT is grateful for the BET and isopropanol analyses.
The authors also acknowledge CBMM for ammoniacal niobium
oxalate donation.
General methods
All chemicals were used as purchased, without further purifica-
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60 F254) and visualized by UV lamp (254 nm). Yields refer
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New J. Chem.
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