Effect of confinement space on adsorption energy and electronic structure of molecule-metal pairs

Abstract

The adsorption of molecules on metal surfaces within confined spaces is key to industrially relevant processes such as catalytic conversions, separations, or gas storage. However, understanding these processes needs more efforts to get a more elaborated picture at the atomic level. Here, we conducted a computational study to get insights into the adsorption of H2, ethylene, and benzene on Fe, Ni, and Cu metallic surfaces at different confinement spaces. For a given molecule-metal system, we obtained the adsorption energy and electron properties. The adsorption energy values varied as a function of the confinement space and were fitted to Lennard-Jones and Morse potential functions. Their fitting parameters followed the trend Fe > Ni > Cu, which reflects the periodicity of the metal atoms. Electronic structure of the molecule-metal pair also changed as a function of the extent of confinement. We rationalized the responses observed as a form of Le Chatelier’s principle. These results could be important for a better understanding of the energetic contribution of confinement in catalytic processes.