Lucky Number 13: A 13-Layer Polytype of the Alkyne Hydrogenation Catalyst CaGaGe.
Lucky Number 13: A 13-Layer Polytype of the Alkyne Hydrogenation Catalyst CaGaGe.
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DOI：
10.1021/acs.inorgchem.1c02051
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发表时间：
2021-09
影响因子：
4.6
通讯作者：
Kelsey L. Hodge;M. Gray;W. Windl;J. Goldberger
中科院分区：
文献类型：
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作者：
Kelsey L. Hodge;M. Gray;W. Windl;J. Goldberger
多型性是材料形成具有不同堆叠顺序的晶体结构的能力，有时会导致具有相同化学计量和相似局部结构的材料具有截然不同的性能。在此，我们发现了 CaGaGe 的亚稳态 13 层三角 (13T) 多型体，这是一种由 Ca2+ 分隔的 [GaGe]2- 蜂窝体组成的层状金属间相。 13T-CaGaGe是通过电弧熔化元素合成的，并通过中子粉末衍射阐明了其结构。空气稳定的 13T-CaGaGe 每 13 层就有一个未对准的 [GaGe]2- 层，并在 500 °C 退火后转变成更稳定的 4 层六方 (4H) CaGaGe 多型体。无过渡金属的13T-CaGaGe在苯乙炔催化加氢生成苯乙烯和乙苯方面表现出显着的活性，远高于4H多型体。这项工作确定了任何晶体结构的第一个 13 层多型性，并进一步确定了多型性对催化的影响。
Polytypism, the ability of materials to form crystal structures with different stacking sequences, occasionally causes materials with the same stoichiometry and similar local structures to have profoundly different properties. Herein, we discover a metastable 13-layer trigonal (13T) polytype of CaGaGe, a layered intermetallic phase comprised of [GaGe]2- honeycombs separated by Ca2+. 13T-CaGaGe is synthesized from arc-melting the elements, and its structure is elucidated via neutron powder diffraction. Air-stable 13T-CaGaGe has one misaligned [GaGe]2- layer for every 13 and transforms into the more stable 4-layer hexagonal (4H) CaGaGe polytype after annealing at 500 °C. Transition-metal-free 13T-CaGaGe shows remarkable activity in the catalytic hydrogenation of phenylacetylene to styrene and ethylbenzene, much higher than the 4H polytype. This work identifies the first 13-layer polytype for any crystal structure and further establishes the influence of polytypism on catalysis.