Fig. 5: DFT calculations of the CO2 conversion pathway and the transition states of *CO2 protonation.

Calculated adsorption configurations of CO2 and reactive intermediates on przpOs (a) and trzpOs (b). a Gibbs free energy diagrams for CO2 adsorption and CO2 reduction to CH4 by przpOs and trzpOs catalysts. Transition states of przpOs (b) and trzpOs (c) via directly protonation (Pathway I) and via nitrogen heteroatom ferrying (Pathway II).