Linking Experimental and Ab-initio Thermochemistry of Adsorbates with a Generalized Thermochemical Hierarchy

Enthalpies of formation of adsorbates are crucial parameters in the microkinetic modeling of heterogeneously catalyzed reactions, since they quantify the stability of intermediates on the catalyst surface. This quantity is often computed using density functional theory, as more accurate methods are computationally still too expensive, which means that derived enthalpies have a large uncertainty. In this study, we propose a new error cancellation method to compute the enthalpies of formation of adsorbates more accurately from DFT through a generalized connectivity-based hierarchy. The enthalpy of formation is determined through a hypothetical reaction that preserves atomistic and bonding environments. The method is applied to a dataset of 60 adsorbates on Pt(111) with up to 4 heavy (non-hydrogen) atoms. Enthalpies of formation of the fragments required for the bond balancing reactions are based on experimental heats of adsorption for Pt(111). Thus, the proposed methodology creates an interconnected thermochemical network of adsorbates that combines experimental with ab-initio thermochemistry in a single thermophysical database.