Unraveling the role of Ni₁₃ catalyst supported on ZrO₂ for CH₄ dehydrogenation: The d-band electron reservoir

The activation of C−H bonds of CH₄ is a key step for the conversion of methane to chemical commodities. Loading Ni onto ZrO₂ is regarded as a relatively efficient way to harness the beneficial electronic property and the fine dispersion of the Ni catalyst for CH₄ dissociation. Herein we demonstrate the crucial role of Ni₁₃ catalyst supported on ZrO₂ for the dissociation of CH₄. The density functional theory (DFT) results show that the ZrO₂ supported Ni₁₃ stabilizes all species better and facilitates CH₄ activation. The stepwise dehydrogenations of CH₄ on Ni₁₃-ZrO₂(111) exhibits longer C−H bond lengths of ISs , lower E_a, and smaller displacements between the detaching H and the remaining CH_x fragment in TSs . In addition, they are also thermodynamically more feasible. However, without the ZrO₂ support on Ni₁₃, the opposite results are obtained. Consequently, the ZrO₂ modified Ni₁₃ is more superior to the original Ni₁₃ in CH₄ dehydrogenation. The electronic analysis combining DFT calculations confirmed that the larger overlap between C 2p and Ni 3d, and the electron transfer of Ni→C cause the weaker C 2p−H 1s hybridization. In addition, the reduction of electron transfer of H→C leads to a stronger interaction between Ni and C along with a weak C−H bond. Hence, the ZrO₂ support serves as the d-band electron reservoir at Ni₁₃ and it is benefit to the activation of C−H bonds in CH₄ dehydrogenation.