How covalence breaks adsorption-energy scaling relations and solvation restores them.

ABSTRACT: It is known that breaking the scaling relations between the adsorption energies of *O, *OH, and *OOH is paramount in catalyzing more efficiently the reduction of O₂ in fuel cells and its evolution in electrolyzers. Taking metalloporphyrins as a case study, we evaluate here the adsorption energies of those adsorbates on the metal centers Cr, Mn, Fe, Co, Ni and Cu, using H, F, OH, NH₂, CH₃, and BH₂ as ring ligands. We show that covalence systematically breaks scaling relations under vacuum by strengthening certain M-OOH bonds. However, covalence modifies adsorbate solvation in solution depending on the degree of covalence of the metal-adsorbate bonds. The two effects have similar magnitudes and opposite signs, such that scaling relations are restor

SUBMITTER: Calle-Vallejo F 

PROVIDER: S-EPMC5308396 | biostudies-literature | 2017 Jan

REPOSITORIES: biostudies-literature