(509at) Designing Electro-Catalysts for the Oxygen Evolution Reaction: A Prisoner of Adsorbate Scaling Relations

The well-known adsorbate scaling relations between the different reaction intermediates involved in the oxygen evolution reaction (OER), imposes the limitation of a minimum required overpotential on oxide surfaces. This serves as an impediment in the design of highly active catalysts to further alleviate the sluggish kinetics associated with the OER. While several strategies have been tested in an attempt to break the scaling relations, the origin of the scaling relations have not been investigated in detail. In a recent study, we showed that hetero-structured oxides involving a semi-conducting host with transition metals doped in the sub-surface activate an otherwise inert host for the OER¹, which was also experimentally verified². Here, we probe the electronic structure origin of the activation mechanism involved in these materials through an extensive analysis of the electronic density of states obtained using first-principles density functional theory (DFT). We find that unique features in the surface atoms along with existence of gap states dominated by the dopants all contribute to the chemisorption energy of the different adsorbates. Further, by combining the principles of the Newns-Anderson model³, d-band model⁴, and the concerted-coupling model⁵, we identify an electronic structure descriptor that captures the trends in the adsorption energy accurately. The identification of this common electronic structure fingerprint rationalizes the origin of the adsorbate scaling relations on oxide surfaces, while also providing paths to improving the atomistic design of electro-catalysts for the OER.

Reference:

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