Fig. 4: Theoretical calculations and possible reaction paths for CO2 hydrogenation.

Projected density of states for (a) Cu–N4 and (c) Cu–N3 SACs, and the Fermi level is indicated by the dashed line. Energy profiles for (b) CO2 hydrogenation via formate pathway over Cu–N4 SAC and (d) CO2 hydrogenation via RWGS pathway over Cu–N3 SAC. Reaction pathways and corresponding atomic configurations for CO2 hydrogenation to (e) CH3OH and (f) CO. The temperature is set as 423 K. The yellow, blue, gray, red and white balls in (e) and (f) represent as Cu, N, C, O, and H atoms, respectively.