Shi Xue-Rong, Zhang Yajing, Zong Shibiao, Gu Wen, Ma Pan, Lu Na
School of Material Engineering, Shanghai University of Engineering Science, 333 Longteng Road, Songjiang District, Shanghai 201620, China.
Institute of Physical Chemistry, University of Innsbruck, Innrain 80-82, Innsbruck A-6020, Austria.
Nanomaterials (Basel). 2019 Mar 2;9(3):331. doi: 10.3390/nano9030331.
Comprehending the bond nature of ethylene-metal clusters at the atomic level is important for the design of nanocatalysts and their applications in the fields of fine chemistry and petroleum refining. The growth of Ir (n = 1⁻10) on γ⁻Al₂O₃(110) and ethylene adsorption on bare and γ⁻Al₂O₃(110)-supported Ir (n = 1⁻10) clusters were investigated using the density functional theory (DFT) approach. The mode stability of ethylene adsorption on the bare Ir clusters followed the order π > di-σ > B-T, with the exception of Ir₈ where the π structure was less stable than the di-σ configuration. On supported Ir (n = 4⁻7 and 10) the stability sequence was π > di-σ > di-σ' (at interface), while on supported Ir (n = 2, 3, 8, and 9) the sequence changed to di-σ > π > di-σ' (at interface). Two-thirds of ethylene adsorption on the supported Ir clusters were weaker than its adsorption on the bare Ir clusters. The pre-adsorbed ethylene at the interface was found to facilitate the nucleation from the even-sized supported Ir to odd-sized Ir clusters, but hindered the nucleation from the odd-sized Ir to even-sized Ir clusters.
在原子水平上理解乙烯 - 金属簇的键性质对于纳米催化剂的设计及其在精细化学和石油精炼领域的应用至关重要。使用密度泛函理论（DFT）方法研究了Ir（n = 1⁻10）在γ⁻Al₂O₃(110)上的生长以及乙烯在裸Ir（n = 1⁻10）簇和γ⁻Al₂O₃(110)负载的Ir（n = 1⁻10）簇上的吸附情况。乙烯在裸Ir簇上吸附的模式稳定性顺序为π > 双σ > B - T，但Ir₈除外，其π结构不如双σ构型稳定。在负载的Ir（n = 4⁻7和10）上，稳定性顺序为π > 双σ > 双σ'（在界面处），而在负载的Ir（n = 2、3、8和9）上，顺序变为双σ > π > 双σ'（在界面处）。负载的Ir簇上三分之二的乙烯吸附比其在裸Ir簇上的吸附弱。发现界面处预吸附的乙烯促进了偶数尺寸负载的Ir向奇数尺寸Ir簇的成核，但阻碍了奇数尺寸Ir向偶数尺寸Ir簇的成核。
