Charge transfer boosts up methane adsorption and activation on three-coordinated metal sites

Abstract

The activation and conversion of CH4 has attracted great interest due to its mitigation impact on the greenhouse gas and contribution to the high value-added chemicals. However, the activation of CH4 is the rate-limiting step due to the high symmetry of the molecule and its chemical inertness. In this study, we constructed active sites with specific geometry for methane activation based on the Nickel and other post-transition metals, where the interactions were significantly enhanced by 0.2∼0.6 eV varying with different VIII group metal types. With advanced electronic structure analysis methods, the origin of this interaction was unraveled, that is the Coulomb attraction induced by charge transfer from hydrogen of methane to three-coordinated metal Ni sites, rather than the covalent bonding or dispersion interaction. This enhancement not only increases the collision possibility by several orders of magnitude, but also lowers the barrier of CH bond breaking. These findings provide deep insight on the methane activation on metal catalysts and shed the light to design more efficient methane conversion catalysts.