Unveiling the effects of Cu doping on the H2 activation by CeO2 surface frustrated Lewis pairs

TL;DR

This study uses density functional theory to explore how Cu doping affects the properties of frustrated Lewis pairs on CeO2 surfaces, influencing hydrogen activation and providing insights for catalyst design.

Contribution

It reveals how Cu doping modifies FLP properties and H2 activation energetics on CeO2 surfaces, guiding future experimental catalyst development.

Findings

Cu doping reduces O vacancy formation energy.

Cu influences FLP formation and properties.

Doping enhances thermodynamics but hinders kinetics of H2 activation.

Abstract

Recently, the solid-state frustrated Lewis pairs (FLPs) on the surface of CeO2 have been demonstrated to effectively catalyze the selective hydrogenation of unsaturated substrates, hence, the relationship between their intrinsic properties and H2 activation at the atomic scale has attracted great attention. In this work, the effects of Cu doping on the intrinsic FLPs properties for different facets of CeO2 is investigated by using density functional theory calculations, including the geometric parameters between Lewis acid-base centers, and the reactivity of Lewis acid-base towards H2 activation. The study demonstrates that introducing O vacancies on different crystal facets of CeO2 creates FLPs with the ability to efficiently cleavage hydrogen molecules. After the substitution of Ce with Cu, the inadequate electron availability of Cu to bond with O contributes to a reduction in the formation energy of O vacancies. Importantly, Cu exert an influence not only on the intrinsic properties of FLPs but also on the formation of new Ce-O and Cu-O FLPs. Considering the H2 activation, the doping of Cu results in an enhancement for the thermodynamics by decreasing the reaction energies, while a hinderance for the kinetics by increasing the energy barriers. Overall, with these theoretical investigations, we propose certain hints for the future experimental studies concerning the synthesis of Cu doped CeO2 catalysts for the H2 activation and hydrogenation reactions.