Homogeneous Electrocatalytic CO 2 Hydrogenation

Research on homogeneous electrocatalytic CO2 hydrogenation is driven by both the global demand for improved technology in renewable fuel production and a wide scope for discovery in the rich fundamental chemistry of CC coupling and CH bond formation reactions and their mechanisms. Homogeneous electrocatalysts are a promising molecular platform to hydrogenate CO2 because they are incredibly diverse in both metal–ligand or metal–metal bonded structures and core electronics dictated by the frontier molecular orbitals of these structures. These structures can be readily tuned via synthetic inorganic chemistry to tune reactivity and to study mechanism. Fundamentally, CO2-to-formate conversion requires two electrons and one proton. The 2e−/1 H+ process suffers from slow rates of conversion at solid electrodes. One strategy to enhance rates of CO2 hydrogenation is to use a metal-based electrocatalyst capable of converting two electrons and one proton into a reactive metal–hydride. In this chapter, we offer an overview of homogeneous electrocatalysts, which hydrogenate CO2 to formate. We discuss how the metal–hydride is directed toward CO2 to produce formate by considering the kinetic and thermodynamic aspects of these electrocatalysts. We further discuss strategies for targeting C1 products beyond formate to further reduced products (i.e. formaldehyde and methanol).