AB INITIO DENSITY STUDY OF N AND O COADSORPTION ON PT(100) AND PT(111)

AB INITIO DENSITY STUDY OF N AND O COADSORPTION ON PT(100) AND PT(111)

Abstract:

The coadsorption of nitrogen (N) and oxygen (O) on platinum (Pt) surfaces plays a crucial role in various catalytic processes, including ammonia synthesis, fuel cells, and selective oxidation reactions. In this study, we employ ab initio density functional theory (DFT) calculations to investigate the adsorption behavior and energetics of N and O coadsorption on two different Pt surfaces: Pt(100) and Pt(111).

Our calculations are based on periodic slabs with multiple layers, and the exchange-correlation functional is treated within the generalized gradient approximation (GGA). The adsorption energies and geometries of N and O species on Pt surfaces are obtained by fully relaxing the atomic positions until the forces on each atom are below a predefined convergence threshold.

For the Pt(100) surface, we find that the preferred adsorption site for both N and O species is the hollow site. The N-N distance in the coadsorbed system is significantly larger than that in the pure N adlayer, indicating a weak interaction between N atoms. On the other hand, the O-O distance in the coadsorbed system is slightly larger than that in the pure O adlayer, suggesting a weak repulsion between neighboring O atoms. The coadsorption of N and O on Pt(100) is found to be energetically favorable, with a small binding energy.

For the Pt(111) surface, the preferred adsorption site for N is the fcc hollow site, while O prefers to adsorb in the atop site. The N-N and O-O distances in the coadsorbed system are similar to those in the pure N and O adlayers, respectively, indicating minimal influence from the coadsorption. The binding energy for N and O coadsorption on Pt(111) is found to be higher compared to Pt(100), suggesting a stronger interaction between N, O, and the Pt(111) surface.

The results of this study provide valuable insights into the coadsorption behavior of N and O on Pt surfaces, which can aid in the design and optimization of Pt-based catalysts for various applications. Further investigations could involve exploring the effect of coverage, temperature, and alloying elements on the coadsorption behavior, as well as considering the dynamic aspects of the system using molecular dynamics simulations.

Keywords: Ab initio calculations, density functional theory, coadsorption, platinum surfaces, nitrogen, oxygen, adsorption energetics, catalysis.

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