Chutia Arunabhiram, Thetford Adam, Stamatakis Michail, Catlow C Richard A
School of Chemistry, Brayford Pool, University of Lincoln, Lincoln, LN6 7TS, UK.
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.
Phys Chem Chem Phys. 2020 Feb 14;22(6):3620-3632. doi: 10.1039/c9cp05476f. Epub 2020 Jan 29.
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 CO, and H. 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.
我们展示了一项关于水煤气变换（WGS）反应在Pd(100)表面上的密度泛函理论（DFT）和动力学蒙特卡罗（KMC）相结合的研究。我们提出了一种机制，在一个单一框架内包含WGS的氧化还原和缔合途径，该机制由七个核心基元步骤组成，这反过来又涉及水分子的分裂，随后在Pd(100)表面产生一个氢原子和一个羟基物种。在接下来的步骤中，这些中间体然后相互重组并与CO反应，导致CO和H的生成。为了完整描述该机制，还考虑了涉及表面中间体物种扩散和吸附的其他七个基元步骤。给出了每个反应物、产物以及核心基元步骤的过渡态的几何和电子性质。我们还讨论了这些基元步骤的反应物、过渡态和产物的巴德电荷和自旋密度分析。我们的研究表明，WGS反应在Pd(100)表面上通过直接氧化和羧基路径同时进行。
