The kinetics and mechanism of nitrogen monoxide (NO) adsorption and oxidation on a tungsten oxide nanocrystalline surface have been studied. First principle calculations were performed within the framework of density functional theory with the ONIOM method at the (B3LYP/LANL2DZ:UFF) level. The activation energy for the rate-determining step of the reaction was determined as 0.45 eV. NBO analysis confirmed that charge transfer has occurred from the adsorbate to the surface. Density of state spectral analysis showed that the Fermi level was shifted to higher values and confirmed the effective interaction between the nanocrystal and adsorbate. HOMO–LUMO analysis showed that crystal band gap was reduced after adsorption. Quantum reactivity indices showed that the chemical hardness was reduced after adsorption which corresponded to the band gap reduction. The electronic chemical potential was shifted to more positive values while the electrophilicity of the surface was reduced after adsorption. These parameters predict that charge transfer has occurred to the surface.

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