Molecular Catalysis of CO2 Reduction with a Zn (II)–Bipyridine Complex

This work investigates the coordination compound [Zn(2,2-bpy)3](BF4)2 as a catalyst for the molecular reduction of CO2. The synthesis and characterization of the complex are reported, along with electrochemical studies conducted both in the presence and absence of CO2. In the absence of CO2, reduction of the 2,2′-bipyridine ligands was observed (Epa(I) = −1.84 V vs. Fc/Fc+ and Epa(II) = −2.18 V vs. Fc/Fc+). In contrast, under a CO2 atmosphere, catalytic molecular activity toward CO2 reduction was detected (Epk(I) = −1.90 V vs. Fc/Fc+ and Epk(II) = −2.18 V vs. Fc/Fc+). Foot of the wave analysis (FOWA) was employed to determine the catalytic rate constant (k = 1.352 × 103 M−1 s−1) for CO2 reduction. Spectroelectrochemical experiments were also carried out in both the presence and absence of CO2. Density functional theory (DFT) calculations were conducted to understand the interaction of the complex with CO2. Bulk electrolysis and FTIR analysis suggest that oxalate is the product of the CO2 reduction.