Designing Nickel-based catalysts for the hydrogenation of CO2 under Ambient conditions: A computational study

Abstract

Recent developments, industrialization, and modernization lead to production of more and more pollutants (such as CO2: ∼ 417.06 ppm) and such rapid growth of CO2 level results in global warming and the greenhouse effect. So, it is essential to conduct research on converting CO2 into fuels using carbon-neutral energy. Recent research on molecular catalysts has improved the rates of converting CO2 to formate. However, these catalysts require extremely high temperatures and pressures and are made of expensive metals like iridium, ruthenium, and rhodium. Herein, DFT-based computational studies have been performed on the catalytic hydrogenation of CO2 by different Ni(II) complexes in ambient conditions. Using state-of-the-art calculations, we demonstrate how the geometry and spin states of Ni(II) complexes containing different types of ligands affect their catalytic role in CO2 hydrogenation. It has been reported that hydride transfer is the most crucial step for such kind of hydrogenation reaction. We start with previously synthesised Ni-bis(diphosphine) complexes of type NiP4 and by extrapolating the concept, we propose a novel kind of Ni-PNP complex with a significantly lower hydride transfer barrier. We also calculate the hydricities of the nickel hydride complexes in order to correlate these thermodynamic parameters with the kinetic barrier of hydride transfer.