Enhanced electrocatalytic activity of iron amino porphyrins using a flow cell for reduction of CO2 to CO

The flexibility of molecular catalysts is highly coveted for the electrochemical reduction of carbon dioxide (CO2) to carbon monoxide (CO) in both homogeneous and heterogeneous systems. While the electrocatalytic activity of molecular catalysts has been widely studied in H-cells; their less studied capabilities in more efficient flow cell reactors have the potential to rival that of heterogeneous catalysts. In this work, a comparative study of amino functionalized iron-tetraphenylporphyrins (amino-Fe-TPPs) immobilized onto carbonaceous materials in both H-cells and flow cells was conducted to selectively reduce CO2 to CO. In a flow cell set up operating in alkaline media, the resulting hybrid catalyst exhibits 87% faradaic efficiency (FE) with extraordinary current density (j) of 119 mA/cm2 and turnover frequency (TOF) of 14 s−1 at −1.0 V vs. RHE. This remarkable catalytic activity was achieved through thoughtful combination of molecular and flow cell design that provides an effective strategy for future immobilized heterogeneous approaches toward CO2 reduction reactions (CO2RRs).