Ru-pincer complexes as charge transfer mediators in electrocatalytic CO2 reduction

In this work, we unravel the role of the system components in the charge transfer processes occurring in the 2electron reduction of CO2. We focus our analysis on the pincer-complex/graphene composite system in order to explain the role of the donors of the pincer ligands in the elementary charge transfer processes. To achieve this goal, we have used the unique combination of the constrained DFT method and computational hydrogen electrode. The results obtained this way allowed us to conclude that the catalytic performance of the system depends to a great extent on the electron-donating properties of the Ru-pincer complex. We have determined, that the optimal charge transfer in the system is due to the easy, single-step transfer to the activated CO2 molecule and the energies required for such transfer are comparable to the limiting potential of the reaction.