Thermodynamic Descriptors for Molecules That Catalyze Efficient CO2 Electroreductions

Guiding proton and electron transfers in an energetically efficient manner remains a hurdle in renewable energy catalysis. To help identify and better understand efficient CO2 conversion catalysts, we used first-principles quantum chemistry to determine pH and electrode potential dependent energies for different classes of aromatic N-heterocycles based on pyridine and imidazole moieties. From these data, we locate Pourbaix diagram triple points that denote the electrochemical conditions where these molecules would facilitate energetically efficient proton or hydride shuttling. Within surprisingly reasonable accuracy, the calculated molecular Pourbaix diagram triple points correspond to experimental conditions under which molecular-promoted CO2 reduction has been observed. This indicates a novel thermodynamic descriptor suitable for high-throughput computational screening can be used to predict molecular cocatalysts and their ideal reaction conditions for renewable energy catalysis.