Secondary Coordination Effects of Adjacent Metal Center in Metal-Nitrogen-Carbon Improve Scaling Relation of Oxygen Electrocatalysis

Heterogenous single-atom catalysts (SACs) are reminescent of homogenous catalysts because of similarity of structural motif of active sites, showing the potential of using the advantage of homogenous catalysts to tackle challenges in hetereogenous catalysis. In heterogeneous oxygen electrocatalysis, the homogeneity of adsorption patterns of reaction intermediates leads to scaling relationships that limit their activities. In contrast, homogeneous catalysts can circumvent such limits by selectively altering the adsorption of intermediates through secondary coordination effects (SCE). This inspired us to explored potential SCE in metal-nitrogen-carbon (M-N-C), a promising type of oxygen evolution electrocatalysts. We introduced SCE with a neighboring metal site, which can modulate the adsorption strengths of oxygen-containing intermediates. First-principles calculations show that the second site in heteronuclear duo four-nitrogen-coordinated metal-center can induce SCE that selectively stabilize the OOH intermediate, but with minor effects on the OH intermediate, and thereby, disrupt scaling relation between oxygen-species, and eventually increase the catalytic activity in oxygen evolution reactions. Additionally, the activity of oxygen reduction reaction of selected M-N-C is also enhanced by such SCE. Our computational work underscored the critical role SCE can have in shaping activities of SACs, particularly in altering scaling relationships favorably, and demonstrated its potential of addressing catalytic challenges in heterogeneous catalysis.