Breaking the scaling relations for oxygen reduction reaction on nitrogen-doped graphene by tensile strain

The scaling relations between adsorption energies of different reaction intermediates on a variety of surfaces simplify the catalyst design, but meanwhile they make it difficult to achieve the optimal catalyst. The oxygen reduction reaction (ORR) at the cathode of fuel cells, for instance, cannot attain the ideal efficiency even with the nowadays best-performed catalysts, due to the correlation between the adsorption energies of O, OH and OOH. In this work, based on the nitrogen doped graphene, we compare the ORR reaction on active sites with different deformation while in similar structural and chemical environments. Since both the tensile strain and the adsorption of O tend to stretch and even break the N-C∗ bond, tensile strain enhances the adsorption strength of O atom while leaving that of OH and OOH approximately unchanged. In contrast, the local curvature cannot uncouple the correlation between the adsorption strength of O, OH and OOH. The results suggest that it is possible to improve the catalytic performance by tuning the structure of catalyst to be in selective resonance with adsorption of a specific intermediate, which provides a new way to design optimal catalysts.