Co incorporated pentagraphene as an efficient single-atom catalyst for reduction of CO2: First-principles investigations

Abstract

Hydrogenation of carbon dioxide (CO2) to formic acid is explored through density functional theory calculations over Co decorated penta-graphene (Co@PG) as single atom catalyst (SAC). Co is successfully stabilized over pentagraphene due to strong overlapping of Co-3d and C-2p states of pentagonal ring of pentagraphene near fermi level. The higher diffusion barrier for Co over pentagraphene evince that the clustering of Co atom is restricted. This suggests that Co@PG can be used as a catalyst for reducing CO2. Moreover, the Hirshfeld charge density, molecular electrostatic potential and spin density analysis indicates that the Co site is the highly active site for CO2 hydrogenation reaction. Both CO2 and H2 show strong interaction with Co@PG. In co-adsorbed state, the interactions are even larger due to greater mutual polarization of reactants and localization of positive charge on Co with adsorption energy of -2.57 eV. The hydrogenation can proceed at ambient temperature due to a small energy barrier of 0.29 eV, the competitive reaction i.e. CO hydrogenation with CO2 hydrogenations almost impossible over the catalyst surface due to larger energy barriers i.e. 1.98 eV. Thus, this work shows that Co@PG can be used as an efficient and promising catalyst for CO2 hydrogenation at room temperature.