Curvature-induced electronic tuning of molecular catalysts for CO2 reduction

Molecular complexes such as phthalocyanines and porphyrins are attractive due to their outstanding performance towards CO2-to-CO conversion. In this work, immobilized cobalt phthalocyanine (CoPc) is prepared using a CVD-type procedure. Our theoretical calculations suggest that depositing CoPc onto a highly curved substrate leads to structural deformation and electronic tuning that can decrease the activation barrier of CO2. Consistent with theoretical predictions, the intrinsic activity of CoPc supported on SWCNTs is improved by two folds compared to that on less-curved surfaces such as reduced graphene oxide (rGO) or multi-wall carbon nanotubes (MWCNTs). The catalyst exhibits a high Faradaic efficiency for CO of 80% at a low overpotential of 240 mV. At a higher overpotential of 490 mV, a TOF of 26.0 s(-1) and a TON of ca. 90 000 are obtained with a near-unity Faradaic efficiency.