Influence of the tensile strain on CH4 dissociation on Cu(1 0 0) surface: A theoretical study

Abstract

Tensile strain is widespread on the catalyst surface due to the lattice mismatch between the catalyst and substrate, such as Cu/MgO in this work. Thus, it is important to investigate the influence of tensile strain on the catalytic properties. In this study, we have investigated the CH4 dissociation on Cu(100) surface by considering the tensile strain. Our results showed that compared with the unstrained Cu(100) surface, the most stable sites for dissociation species CHx (x=0⿿3) and H adsorption on strained surface remain unchanged. The surface strain strengthens CHx (x=0⿿3) adsorption, while weakens H adsorption. The elementary reaction for CH4 dissociation with the largest electronic energy barrier changes from CH⿿C+H on the unstrained surface to CH4⿿CH3+H on the strained surface (for strain equal to and larger than 3%), in agreement with the experimental observation that CH4 dissociation into CH3 and H is the most difficult reaction. The tensile strain accelerates C migration while has no obvious influence for C polymerization. Both DFT calculations and microkinetic model demonstrated that the strain hinders the CH4 dissociation process on Cu(100) surface. CH4 dissociation rate depends sensitively on the magnitude of the surface tensile strain.