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

Heterogenous single-atom catalysts (SACs) are reminiscent of homogeneous catalysts because of the similarity of structural motif of active sites, showing the potential of using the advantage of homogeneous 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 (SCEs). This inspired us to explore potential SCEs in metal-nitrogen-carbon (M-N-C), a promising type of oxygen evolution electrocatalyst. We introduced SCEs with a neighboring metal site that can modulate the adsorption strengths of oxygen-containing intermediates. First-principles calculations show that the second site in the heteronuclear duo four-nitrogen-coordinated metal center can induce SCEs that selectively stabilize the OOH intermediate but with minor effects on the OH intermediate and, thereby, disrupt the 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 SCEs can have in shaping activities of SACs, particularly in favorably altering scaling relationships, and demonstrated its potential to address catalytic challenges in heterogeneous catalysis.