Phosphine Modulation for Enhanced CO 2 Capture: Quantum Mechanics Predictions of New Materials.

It is imperative to develop efficient CO 2 capture and activation technologies to combat the rising levels of deleterious greenhouse gases in the atmosphere. Using Quantum Mechanics methods (Density Functional Theory), we propose and evaluate several metal-free and metal-containing phosphines that provide strong CO 2 binding under ambient conditions. Depending on the electron donating capacity of the phosphine and the ability of the P-bound ligands to hydrogen bond to the CO 2 , we find that the CO 2 binding can be as strong as -18.6 kcal/mol downhill, which should be quite adequate for ambient conditions. We explore some modifications of the phosphine to improve CO 2 binding, and we elucidate which chemical descriptors correlate directly with CO 2 binding energy. Specifically, we find that charge accumulation on the CO 2 unit of the CO 2 -bound adduct has the greatest correlation with CO 2 binding affinity. Finally, we probe the mechanism for CO 2 reduction to CO and methanol in aqueous media.