Illustrating the surface chemistry of nitrogen oxides (NOx) adsorbed on rutile TiO2 (110) with the aid of STM and AIMD simulation†

Abstract

The family of nitrogen oxides such as NO, NO₂, and N₂O is considered as major anthropogenic environmental pollutants. Understanding the chemical interaction between adsorbed NO_x molecules and the rutile TiO₂ surface is important for environmental NO_x reduction. In this work, we have derived the adsorption mechanism of nitrogen oxide (NO_x) molecules on the rutile TiO₂ (110) surfaces by using density functional theory (DFT)-based computations. The most suitable adsorption sites for the nitrogen oxide molecules on the TiO₂ (110) surfaces are identified from the adsorption energetics. The complete charge flow process is understood for various NO_x adsorbed on the surface. The variation in the adsorption mechanism of NO, NO₂, and N₂O molecules was explored. Ab Initio Molecular Dynamics (AIMD) simulations are performed to study the stability of NO_x-adsorbed TiO₂ surfaces. Further insights on the ensuing modifications of the TiO₂ (110) surfaces, as well as their structural and thermodynamic stability, are derived. The Scanning Tunneling Microscope (STM) images of the rutile TiO₂ (110) surfaces and with the adsorbents are simulated for the first time, which helps to find the surface morphology of NO_x adsorbed on the TiO₂ surface. The influence of individual constituents of the adsorbed molecules and the surface is explored by analyzing the intricate features of their electronic structures. The present work provides guidelines exploring the interactions of NO_x pollutants adsorbed on rutile TiO₂ (110) surfaces.