Potential-Induced Dynamic Coordination of Nonmetal Atoms Directly Bound to Metal Centers in Graphene-Embedded Single-Atom Catalysts and Its Implications

TL;DR

This study reveals how electrode potential dynamically influences the coordination environment of nonmetal atoms bound to metal centers in graphene-embedded single-atom catalysts, affecting their electronic structure and catalytic behavior.

Contribution

It uncovers potential-driven hydrogenation of nonmetal sites in SACs and demonstrates how this dynamic coordination impacts catalyst stability and activity, providing new mechanistic insights.

Findings

C sites undergo potential-driven hydrogenation

Hydrogenation at N sites is thermodynamically unfavorable

Hydrogenation processes have accessible kinetic barriers

Abstract

Electrode-potential-induced dynamic coordination is an essential factor governing the performance of graphene-embedded single-atom catalysts (SACs). While previous studies have primarily centered on structural dynamics at the metal site, the response of its coordinated nonmetal atoms remains largely unexplored. Here, using Ni SACs with mixed nitrogen/carbon coordination (NiN4-xCx) as representatives, we investigate potential-driven hydrogenation of metal-center-coordinated nonmetallic atoms through constant-potential density functional theory and ab initio molecular dynamics. We find that the C sites directly bound to Ni undergo potential-driven hydrogenation, whereas hydrogenation at N sites is thermodynamically unfavorable. Taking NiNC3 as a representative system, we demonstrate that these hydrogenation processes proceed with accessible kinetic barriers and obey the Br{\o}nsted-Evans-Polanyi relation. The resulting dynamic coordination reshapes the Ni 3d and dz2 orbitals, modulates the stability of the active center, and weakens molecular adsorption through combined electronic and steric effects. These findings reveal that electrode potential and solvent not only regulate the metal center but also dynamically reconfigure its coordination environment, offering novel mechanistic insights into potential-induced coordination dynamics and guiding the rational design of coordination-engineered SACs.