Atomistic Insights Into the Surface Dynamics of Ni(111) During Reverse Water gas Shift Reaction

The conversion of CO 2 ‐H 2 mixtures on Ni‐based catalysts can proceed through either the reverse water gas shift reaction (RWGS) path to produce CO or the CO 2 methanation path to produce CH 4 . The balance between these competing reactions depends on both the reaction conditions and catalyst structure. In this study, using surface‐sensitive infrared and ambient pressure X‐ray photoelectron spectroscopies, we investigate the effect of reaction conditions on the interaction between CO 2 and H 2 on a Ni(111) model catalyst. Our findings highlight the occurrence of RWGS, involving direct dissociation of CO 2 to CO and atomic oxygen, followed by oxygen reacting with hydrogen to form H 2 O, and CO and H 2 O desorption. Hydrogen affects the distribution of CO between hollow and top sites by displacing oxygen from the energetically preferred hollow sites. The overall balance between oxygen production from CO 2 dissociation and oxygen removal by hydrogen governs the oxygen coverage and consequently the distribution of CO between top and hollow sites. This balance is significantly influenced by the reaction temperature and the H 2 /CO 2 partial pressures.