Electronic Modulation of the Cobalt Phthalocyanine on G-C3N4 via Coadsorbing Nitropyrene for Improved Electroreduction of Carbon Dioxide to Carbon Monoxide

Electroreduction of carbon dioxide (CO 2 ER) to carbon monoxide (CO) represents a promising pathway to the production of sustainable fuel and carbon neutrality. Molecular catalysts, such as cobalt phthalocyanine (CoPc), are known to be effective in converting carbon dioxide (CO 2 ) to CO. However, increasing the rate and selectivity of this reaction remains challenging and sometimes complicated. In this work, we report a simple molecule-coadsorption strategy to improve the efficiency of CoPc-catalyzed electrocatalytic conversion of CO 2 to CO on graphitic carbon nitride (g-C 3 N 4 ). By coadsorbing nitropyrene (NPy) molecules, together with CoPc, on the surface of graphitic g-C 3 N 4 via π–π conjugation, the catalytic activity of CoPc increased by 84%, and the Faradaic efficiency (FE) of CO increased up to 98.2% ± 1.6% in a H-type cell. This FE could further improve up to ∼100% in a flow cell. The improved catalysis performance could be attributed to the NPy-modulated change in electronic structure of the cobalt center in CoPc and the modulated reaction thermodynamics. Overall, this work paves a new way for fine modulation of the electronic structure of molecular catalysts for improvements in both activity and selectivity.