Electronic Tuning of Cobalt Porphyrins Immobilized on Nitrogen-Doped Graphene for CO₂ Reduction

Electroreduction of CO₂ into CO can be catalyzed by cobalt porphyrins, and the performance can be improved by peripheral functionalization or heterogenization. Herein, we report a facile approach to electronically tune the metal center. Through the introduction of nitrogen atoms onto the graphene support, the activity of cobalt porphyrin/graphene composite can be increased by a factor of 2. Density functional theory calculations and X-ray photoelectron spectroscopy analysis revealed that nitrogen atoms embedded in graphene increase the electron density of cobalt atoms and boost its activity for CO₂ electroreduction. Such a methodology has the potential to be extended to other catalytic systems involving molecular catalysts.