Abstract:
The activation of C−H bonds of CH
4 is a key step for the conversion of methane to chemical commodities. Loading Ni onto ZrO
2 is regarded as a relatively efficient way to harness the beneficial electronic property and the fine dispersion of the Ni catalyst for CH
4 dissociation. Herein we demonstrate the crucial role of Ni
13 catalyst supported on ZrO
2 for the dissociation of CH
4. The density functional theory (DFT) results show that the ZrO
2 supported Ni
13 stabilizes all species better and facilitates CH
4 activation. The stepwise dehydrogenations of CH
4 on Ni
13-ZrO
2(111) exhibits longer C−H bond lengths of ISs , lower
Ea, 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 ZrO
2 support on Ni
13, the opposite results are obtained. Consequently, the ZrO
2 modified Ni
13 is more superior to the original Ni
13 in CH
4 dehydrogenation. The electronic analysis combining DFT calculations confirmed that the larger overlap between C 2
p and Ni 3
d, and the electron transfer of Ni→C cause the weaker C 2
p−H 1
s 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 ZrO
2 support serves as the
d-band electron reservoir at Ni
13 and it is benefit to the activation of C−H bonds in CH
4 dehydrogenation.