A DFT and KMC based study on the mechanism of the water gas shift reaction on the Pd(100) surface

Arunabhiram Chutia; Adam Thetford; Michail Stamatakis; C Richard A Catlow

doi:10.1039/c9cp05476f

A DFT and KMC based study on the mechanism of the water gas shift reaction on the Pd(100) surface

Phys Chem Chem Phys. 2020 Feb 14;22(6):3620-3632. doi: 10.1039/c9cp05476f. Epub 2020 Jan 29.

Authors

Arunabhiram Chutia¹, Adam Thetford², Michail Stamatakis³, C Richard A Catlow⁴

Affiliations

¹ School of Chemistry, Brayford Pool, University of Lincoln, Lincoln, LN6 7TS, UK. achutia@lincoln.ac.uk and UK Catalysis Hub, RCaH, Rutherford Appleton Laboratory, Didcot, OX11 OFA, UK.
² UK Catalysis Hub, RCaH, Rutherford Appleton Laboratory, Didcot, OX11 OFA, UK and Department of Chemistry, University of Manchester, UK and Department of Chemistry, University College London, Gordon Street, London, WC1H 0AJ, UK. c.r.a.catlow@ucl.ac.uk.
³ Department of Chemical Engineering, University College London, Torrington Place, London, WC1E 7JE, UK.
⁴ UK Catalysis Hub, RCaH, Rutherford Appleton Laboratory, Didcot, OX11 OFA, UK and Department of Chemistry, University College London, Gordon Street, London, WC1H 0AJ, UK. c.r.a.catlow@ucl.ac.uk and Cardiff Catalysis Institute, School of Chemistry, Cardiff University, Cardiff, CF10 3AT, UK.

PMID: 31995067
DOI: 10.1039/c9cp05476f

Abstract

We present a combined density functional theory (DFT) and Kinetic Monte Carlo (KMC) study of the water gas shift (WGS) reaction on the Pd(100) surface. We propose a mechanism comprising both the redox and the associative pathways for the WGS within a single framework, which consists of seven core elementary steps, which in turn involve splitting of a water molecule followed by the production of an H-atom and an OH-species on the Pd(100) surface. In the following steps, these intermediates then recombine with each other and with CO leading to the evolution of CO₂, and H₂. Seven other elementary steps, involving the diffusion and adsorption of the surface intermediate species are also considered for a complete description of the mechanism. The geometrical and electronic properties of each of the reactants, products, and the transition states of the core elementary steps are presented. We also discuss the analysis of Bader charges and spin densities for the reactants, transition states and the products of these elementary steps. Our study indicates that the WGS reaction progresses simultaneously via the direct oxidation and the carboxyl paths on the Pd(100) surface.