First principles investigation of cobalt-phthalocyanine active site tuning via atomic linker immobilization for CO2 electroreduction.

[Display omitted] • Improving CoPc catalyst performance by identifying potential atomic-style linkers. • Calculations suggest improved CO 2 ERR performance for the NH, PH and S linkers. • Unoccupied spin-down d z 2 orbital components facilitate initial CO 2 adsorption. • Contrary to previous experiments, the NH 2 linker shows weak bonding to CoPc. We investigate the CO 2 electroreduction reaction (CO 2 ERR) using first principles calculations, for the active site tuning of cobalt phthalocyanine (CoPc) via distinct atomic linker species which immobilize CoPc on a carbon nanotube (CNT) substrate. Eight different linker species are studied, along with the effect of linker hydrogenation. Superior reaction performance is predicted for the NH, S and PH linkers, which show activated CO 2 adsorption. This results from spin polarization causing unoccupied d z 2 spin-down states of the cobalt active site at, or above, the Fermi level. Using an 'on-catalyst' reaction scheme, calculated activation barriers for COOH formation and CO desorption are lower for the CoPc-PH-CNT system compared to the CoPc-NH-CNT system and CoPc remains attached to PH-CNT throughout the reaction. We thus expect the PH linker system to have similar or better CO 2 ERR performance compared to the NH and S linker systems but at a slightly higher electrode potential. [ABSTRACT FROM AUTHOR]