Mechanistic Understanding of NO₂ Dissociation on a Rutile TiO₂ (110) Surface: An Electronic Structure Study

Abstract

Understanding the mechanism of NO2 interaction on semiconductor surfaces such as TiO2 is a key step in designing the catalytic processes for conversion of NO2 to useful products. In the present work, through density functional theory calculations and NEB simulations, we have performed a comprehensive electronic structure study and established the reaction steps for efficient conversion of NO2 to HONO on TiO2 surface in the presence of water vapor. We predict the dimerization of NO2 to form a metastable N2O4. The latter’s dissociation to NOδ+and NO3δ− complexes occurs in two pathways: (i) direct disproportionation reaction and (ii) through formation of NO2δ+and NO2δ− intermediates followed by O transfer. The introduction of H2O on a NO2 chemisorbed surface leads to the formation of nitrous acid through the interaction of NOδ+ with the water. The reaction pathways leading to formation of nitrous and nitric acids are formulated.