Heterometallic Benzenehexathiolato Coordination Nanosheets: Periodic Structure Improves Crystallinity and Electrical Conductivity
Heterometallic Benzenehexathiolato Coordination Nanosheets: Periodic Structure Improves Crystallinity and Electrical Conductivity
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DOI：
10.1002/adma.202106204
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发表时间：
2022-02-20
影响因子：
29.4
通讯作者：
Nishihara, Hiroshi
中科院分区：
文献类型：
--
作者：
Toyoda, Ryojun;Fukui, Naoya;Nishihara, Hiroshi
配位纳米片是一类新兴的2D、自下而上的材料，其具有完全π共轭的、平面的、石墨状结构，具有高电导率。自从他们的发现，已经投入了很大的努力，以扩大各种配位纳米片，然而，在大多数情况下，其低结晶度的厚膜阻碍了实际设备的应用。在这项研究中，镍和铜离子的混合物被用来制造苯六硫醇（BHT）为基础的配位纳米片薄膜，并偶然发现，这种heteromatallicity优先形成一个结构相，提高薄膜的结晶度。光谱和散射测量提供了证据的双层结构与面内周期性排列的铜和镍离子的NiCu2BHT公式。与均质薄膜相比，异质金属薄膜具有更多的晶粒尺寸和取向，从而获得更高的导电性，达到金属行为。低依赖性的Seebeck系数的混合比的镍和铜离子的支持，在电导率数据的大的变化是不是由膜的本征性质的变化引起的。这一发现为提高结晶度和调整2D配位纳米片的功能特性开辟了新的途径。
Coordination nanosheets are an emerging class of 2D, bottom-up materials having fully pi-conjugated, planar, graphite-like structures with high electrical conductivities. Since their discovery, great effort has been devoted to expand the variety of coordination nanosheets; however, in most cases, their low crystallinity in thick films hampers practical device applications. In this study, mixtures of nickel and copper ions are employed to fabricate benzenehexathiolato (BHT)-based coordination nanosheet films, and serendipitously, it is found that this heterometallicity preferentially forms a structural phase with improved film crystallinity. Spectroscopic and scattering measurements provide evidence for a bilayer structure with in-plane periodic arrangement of copper and nickel ions with the NiCu2BHT formula. Compared with homometallic films, heterometallic films exhibit more crystalline microstructures with larger and more oriented grains, achieving higher electrical conductivities reaching metallic behaviors. Low dependency of Seebeck coefficient on the mixing ratio of nickel and copper ions supports that the large variation in the conductivity data is not caused by change in the intrinsic properties of the films. The findings open new pathways to improve crystallinity and to tune functional properties of 2D coordination nanosheets.