Unraveling the Mechanism of Oxygen Electrocatalysis on Transition Metal-Free Single-Atom-Doped Holey Graphyne

Design of transition metal-free electrocatalysts for energy conversion processes, such as oxygen reduction reaction (ORR) and oxygen evolution reaction (OER), holds great promise to advance the renewable energy technologies based on fuel cells and metal air batteries. Herein, a series of main group single-atom-doped holey graphyne (hG) systems for catalyzing ORR and OER using density functional theory calculations are investigated. The influence of single-atom dopants on the structure and electronic properties of hG is examined, observing a general decrease in the bandgap due to the presence of defect-like dopant states near the Fermi level, which facilitates enhanced charge transfer from the doped hG systems to the ORR/OER intermediates. The simulated free energy pathways for ORR and OER demonstrate that Ga-doped hG exhibits excellent catalytic activity toward ORR, while Ge-doped hG emerges as a promising candidate for OER. The ORR overpotential correlated very strongly with the adsorption free energy of the *OH intermediate, highlighting its crucial role in modulating ORR activity. These findings provide valuable insights for the rational design and development of high-performance electrocatalysts for energy conversion applications.