Curvature-Dependent Selectivity of CO2 Electrocatalytic Reduction on Cobalt Porphyrin Nanotubes

The selective electrocatalytic conversion of CO2 into useful products is a major challenge in facilitating a closed carbon cycle. Here, on the basis of first-principles calculations combined with computational hydrogen electrode model, we report a curvature-dependent selectivity of CO2 reduction on cobalt porphyrin nanotubes which are thermodynamically stable, displaying tunable geometric and electronic properties with tube radius. We have found that CO production is preferred on nanotubes with larger diameter, and the predicted current density from microkinetics is larger than that on Au, the best metal catalyst for CO production from CO2 electroreduction. In contrast, highly curved nanotubes with small radii tend to further catalyze CO reduction to CH4 gas and the overpotential is much lower in comparison with the cases on Cu surfaces. The selectivity and the feasibility of synthesis make cobalt porphyrin nanotubes very promising for CO2 conversion.