α,β-不饱和醛在Ni-Pt(111)面上吸附的理论研究

利用密度泛函理论研究了巴豆醛和肉桂醛分子在Pt-Ni-Pt(111)面的吸附构型以及相关电子性质. 吸附构型与吸附能结果表明, 巴豆醛和肉桂醛在覆盖度为1/25 ML的条件下, 以C=C和C=O双键协同吸附在Pt-Ni-Pt(111)面较为稳定, 且肉桂醛与Pt-Ni-Pt(111)面的吸附能远大于巴豆醛. 由Mulliken电荷布局和差分电荷密度可知, 在吸附过程中肉桂醛分子向Pt-Ni-Pt(111)面上转移的电荷数较巴豆醛更多, 相互作用更大. 由电子态密度分析结果可知, 不饱和醛与Pt-Ni-Pt(111)面的吸附作用主要是由于分子的p轨道电子与催化剂d轨道电子之间的相互作用. 由于苯基的存在使肉桂醛分子在Pt-Ni-Pt(111)面上的吸附更强, 且平行于催化剂表面.

Theoretical Study on Adsorption of α,β-Unsaturated Aldehydes on Ni-Pt(111) Surface†

The adsorption configurations of crotonaldehyde and cinnamaldehyde molecules on Pt-Ni-Pt(111) surface and their electronic properties were studied with density functional theory(DFT). The adsorption configurations and adsorption energy values illustrate that synergistic adsorption of crotonaldehyde and cinnamaldehyde molecules on Pt-Ni-Pt(111) surface with C=O and C=C bonds are most stable under the coverage of 1/25 ML. Moreover, the adsorption energy values of cinnamaldehyde on Pt-Ni-Pt(111) surface are much larger than that of crotonaldehyde. By analyzing Mulliken atomic charge population and the deformation density, it is found that the cinnamaldehyde molecule transfers more electrons to the Pt-Ni-Pt(111) surface and interact more strongly. The result of partial density of states(PDOS) indicates that the main reason for the adsorption is due to the interaction of the p orbital electrons of the unsaturated aldehyde molecules with the d orbital electrons of metal surface. And, due to the presence of the phenyl group, the cinnamaldehyde molecule is parallel to the surface of the Pt-Ni-Pt(111) and adsorbed more strongly.