西北農林魏寧副教授課題組：高效黑磷烯手征篩選方法

責任編輯 譚坤

二維材料普遍具有各向異性的特徵，比如不同手性具有不同的電學，力學和熱學性能。一直以來，如何高效分離不同手性的二維材料，用以製備發揮其優勢性能的納米器件，被認為是二維材料研究中重要的問題之一。

近日，西北農林科技大學、西悉尼大學、中國科學院上海應用物理研究所與瑞士蘇黎世聯邦理工學院（ETH）的研究者合作發現，利用黑磷烯在之字形（Zigzag）和扶手椅形（Armchair）兩個手性方向的不同的彎曲剛度（Bending Stiffness），可以高效地分離這兩種不同手征的黑磷烯。

黑磷烯的彎曲形變需要克服彎曲能，而其在 Zigzag 方向的彎曲剛度約為 Armchair 方向的4倍。因此，這一力學的各向異性使得黑磷烯在 Armchair 方向比 Zigzag 方向更容易發生摺疊，彎曲與捲曲。研究者根據這一特性，提出了3種理論模型來實現高效的手性篩選分離，分別是：（1）納米顆粒誘導黑磷烯自包裹；（2）懸空橋模型；（3）納米滾軸模型，如下圖所示：

圖1. 納米液滴誘導黑磷烯自包裹，只有armchair方向發生了自摺疊包裹， zigzag 方向的黑磷烯保持展開狀態。

圖2. 懸空橋模式黑磷烯手續篩選模型，隨著活塞下滑，只有armchair手性的黑磷烯隨著活塞向下移動並脫離了表面。

圖3.通過納米管滾軸捲曲篩選 Armchair 手征黑磷烯，留下 Zigzag 手征黑磷烯

該項研究得到國家自然科學基金委、瑞士聯邦政府基金、中國科學院等單位的共同支持。相關研究成果發表在納米尺度上（Nanoscale, 2018,），並引起海內外實驗組的關注。

相關論文信息

標題Efficient Selection Methods for Black Phosphorene Nanoribbons

期刊Nanoscale

作者Ning Wei, Yang Chen, Yingyan Zhang, Zhou Chui, Xiaoli Hao, Ke Xu, Kun Cai and Jige Chen

DOI:10.1039/C7NR08311D.

摘要 Black phosphorene (BP) has shown anisotropic electronic, mechanical, and thermal properties for various promising applications in recent years. To take full advantage of this unique anisotropy in its further functional design and application, it is paramount to separate BP with well-defined chirality quickly and precisely. In this paper, we propose three efficient methods to separate BP ribbons with different chirality by utilizing their strong chirality-dependent bending stiffness. Our results show that the bending stiffness in the zigzag direction is more than 4 times larger than that in the armchair direction. The mechanical anisotropy and bending-binding competition are used to realize chirality-dependent design. To fold, wrap or scroll the BP nanoribbons, it is necessary to overcome the bending stiffness by adding the binding energy between the BP nanoribbons and the contact surfaces. Due to the mechanical anisotropy, the BP nanoribbons could easily be folded, wrapped and scrolled along the armchair direction rather than the zigzag direction. Therefore, we introduce this characteristic in our chirality separation designs as, the self-folding model to fold up the armchair BP nanoribbons by nanoparticle, the suspension-bridge sieve model to pull down the armchair BP nanoribbons, and the nanorod-roller model to scroll up the armchair nanoribbons. Our separation methods in this research can be extended to other 2D materials with anisotropic mechanical properties. We hope our findings would offer a novel route for manufacturing of BP-based electronic devices and self-assembly nano-devices.

鏈接http://pubs.rsc.org/en/content/articlelanding/2018/nr/c7nr08311d#!divAbstract

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