Bond Energies of Adsorbed Intermediates to Metal Surfaces: Correlation with Hydrogen-Ligand and Hydrogen-Surface Bond Energies and Electronegativities

Abstract

Understanding what controls the strength of bonding of adsorbed intermediates to transition-metal surfaces is of central importance in many technologies, especially catalysis and electrocatalysis. Our recently measured bond enthalpies of -OH, -OCH₃ , -O(O)CH and -CH₃ to Pt(111) and Ni(111) surfaces are fit well (standard deviation of 7.2 kJ mol^-1 ) by a predictive equation involving only known parameters (gas-phase ligand-hydrogen bond enthalpies, bond enthalpies of adsorbed H atoms to that surface, electronegativities of the elements, and group electronegativities of the ligands). This equation is based upon Pauling's equation, with improvements introduced by Matcha, derived here following manipulations of Matcha's equation similar to (but going beyond) those introduced by Schock and Marks to explain ligand-metal bond enthalpy trends in organometallic complexes.

Keywords: Pauling's equation; adsorption energies; calorimetry; surfaces; transition metals.