Computational Discovery of Active and Selective Metal- Nitrogen-Graphene Catalysts for Electrooxidation of Water to H₂O₂

Authors

Payal Chaudhary, University of Nebraska - LincolnFollow
Iman Evazzade, University of Nebraska - Lincoln
Rodion Belosludov,, Tohoku University
Vitaly Alexandrov, University of Nebraska - LincolnFollow

Date of this Version

3-16-2023

Document Type

Article

Citation

ChemCatChem 2023, doi.org/10.1002/cctc.202300055.

Comments

Open access.

Abstract

A direct electrosynthesis of H₂O₂ from either O₂ or H₂O is an attractive strategy to replace the energy-intensive industrial anthraquinone process. Two-electron water oxidation reaction (2e-WOR) offers several advantages over the oxygen reduction reaction such as better mass transfer due to the absence of gasphase reactants. However, 2e-WOR is a more challenging and less studied process with only a handful of metal oxides exhibiting reasonable activity/selectivity properties. Herein, we employ density-functional-theory calculations to screen a variety of metal-nitrogen-graphene structures for 2e-WOR. As a consequence of scaling between the adsorption energies of reaction intermediates, we determine a linear relation between selectivities for the first and second reaction steps of 2e-WOR, viz. that if selectivity toward adsorbed OH is improved, then selectivity toward H₂O₂ at the subsequent step is decreased. We also find that selectivity and activity are linearly scaled in such a way that a higher activity (i. e., a lower overpotential) leads to a lower selectivity for the H₂O₂ formation step. Based on the obtained results several chemistries, e. g., containing NiN_x-C moieties, are predicted to rival the best-performing metal oxides such as ZnO and CaSnO₃ in terms of combination of their activity/selectivity characteristics for 2e-WOR.