Noble Metal Single-Atom Coordinated to Nitrogen, Oxygen, and Carbon as Electrocatalysts for Oxygen Evolution

Tuning the coordination environment centering metal atoms has been regarded as a promising strategy to promote the activities of noble metal single-atom catalysts (SACs). In the present work, first-principle calculations are employed to explore the oxygen evolution reaction (OER) performance of Ir and Ru SACs with chemical coordination being nitrogen (M-N-4-C), oxygen (M-O-4-C), and carbon (M-C-4-C) in graphene, respectively. A "three-step" strategy was implemented by progressively investigating these metrics (stability, catalytic activity, structure-activity relationship). A volcano plot of reactivity is established by using the adsorption-free energy of O* (triangle G(O*)) as a theoretical descriptor. The intrinsic OER activity is IrN4-C > IrO4-C > RuO4-C > RuN4-C > IrC4-C > RuC4-C. The in-depth tuning mechanism of triangle G(O*) can be indicated and interpreted by the d-band centers of the active sites and the crystal orbital Hamilton population analysis of metal-oxygen bonds, respectively.