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 (CO2ER) 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 (CO2) 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 CO2 to CO on graphitic carbon nitride (g-C3N4). By coadsorbing nitropyrene (NPy) molecules, together with CoPc, on the surface of graphitic g-C3N4 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.