Fig. 3: Theoretical analysis of electronic structure of Co1/NOC with different densities.

a Top and side views of differential charge density of x-Co1-N3O1 models. Isosurface: 0.005 e/Å–3. Color legend for isosurface: blue, charge depletion; yellow, charge accumulation. b Projected density of state (pDOS) for the Co 3d orbital. c The relationship between Bader charger and d-band center in various x-Co1-N3O1 models. d The plot of spin moment with respect to Co single-atom density. Inset: The spin density isosurfaces of 0.005 e/Å–3.