First-Principles-Based Kinetic Monte Carlo Simulation of the Structure Sensitivity of the Water–Gas Shift Reaction on Platinum Surfaces

Abstract

Precious metals, such as platinum, have recently been explored as catalysts for the water–gas shift (WGS) reaction. Previous studies have elucidated the underlying reaction mechanism using mean-field models; however, the contribution of different site types, namely, steps and terraces, on the overall reaction rate is an open question, and it remains unclear how structure sensitive the WGS reaction is. The present work addresses these questions using a multiscale modeling approach that integrates density functional theory (DFT) calculations and kinetic Monte Carlo (KMC) simulation. We calculate the reaction barriers and pre-exponential factors of the elementary steps of the WGS mechanism at steps and terraces using DFT. These elementary steps include adsorption and desorption, water and hydroxyl decomposition, and the formation of carboxyl and formate intermediates followed by the formation of CO2. We subsequently incorporate the calculated values into a KMC framework and calculate the turnover frequency f...