Highly Scalable Conversion of Blood Protoporphyrin to Efficient Electrocatalyst for CO$_2$ ‐to‐CO Conversion

Electrochemical CO$_2$ reduction to valuable chemicals represents a green and sustainable approach to close the anthropogenic carbon cycle, but has been impeded by low efficiency and high cost of electrocatalysts. Here, a cost-effective hybrid catalyst consisting of hemin (chloroprotoporphyrin IX iron(III)), a product recovered from bovine blood, adsorbed onto commercial Vulcan carbon is reported. Upon heat treatment, this material shows significantly improved activity and selectivity for CO$_2$ reduction in water while exhibiting good stability for more than 10 h. The heat treatment leads to consecutive removal of the axial chlorine atom and decomposition of the iron porphyrin ring, restructuring to form atomic Fe sites. The optimized hybrid catalyst obtained at 900 °C shows near-unity selectivity for reduction of CO$_2$ to CO at a small overpotential of 310 mV. The insight into transformation of adsorbed Fe complexes into single Fe atoms upon heat treatment provides guidance for development of single atom catalysts