A thermodynamics study of hydrogen interaction with (110) transition metal surfaces

An in-depth understanding of the interactions between hydrogen and transition metal catalysts is of great significance in exploring novel heterogeneous hydrogenation reaction mechanisms. Herein we present a comprehensive study of the interactions of hydrogen on active metal surfaces by using a multiscale method. Six different transition metals of Ni-group and Cu-group are considered. Different from two stable (11 1) and (1 0 0) surfaces, the energetic results of hydrogen species diffusing on and permeating into the active (1 1 0) surfaces are fully addressed from three-dimensional potential energy surfaces and density functional theory calculations. Ab initio thermodynamics calculations show that a stable adsorption phase diagram with full hydrogen coverage preferably forms with decreasing reaction temperature and increasing hydrogen partial pressure, especially on the (1 1 0) surfaces of Ni-group metals without consideration of the reconstruction events. During the evolutions of metal nanoparticles under moderate reaction conditions, the active (1 1 0) surface is difficult to be exposed for Ni-group metal nanoparticles, while for Cu-group metal nanoparticles it is easy to get exposed. These important thermodynamic results will contribute to an in-depth understanding of the interactions between hydrogen species and transition metal catalysts in heterogeneous catalysis.