State Key Laboratory of Mechanics and Control of Mechanical Structures, and Key Laboratory for Intelligent Nano Materials and Devices of Ministry of Education, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, China.
Chem Soc Rev. 2017 Nov 13;46(22):6746-6763. doi: 10.1039/c7cs00261k.
Situated between metals and non-metals in the periodic table, boron is one of the most chemically versatile elements, forming at least sixteen bulk polymorphs composed of interlinked boron polyhedra. In low-dimensionality, boron chemistry remains or becomes even more intriguing since boron clusters with several to tens of atoms favor planar or cage-like structures, which are similar to their carbon counterparts in terms of conformation and electronic structure. The similarity between boron and carbon has raised a question of whether there exists stable two-dimensional (2D) boron, as a conceptual precursor, from which other boron nanostructures may be built. Here, we review the current theoretical and experimental progress in realizing boron atomic layers. Starting by describing a decade-long effort towards understanding the size-dependent structures of boron clusters, we present how theory plays a role in extrapolating boron clusters into 2D form, from a freestanding state to that on substrates, as well as in exploring practical routes for their synthesis that recently culminated in experimental realization. While 2D boron has been revealed to have unusual mechanical, electronic and chemical properties, materializing its potential in practical applications remains largely impeded by lack of routes towards transfer from substrates and controlled synthesis of quality samples.
硼位于元素周期表的金属和非金属之间，是化学性质最广泛的元素之一，形成了至少十六种由相互连接的硼多面体组成的体相多晶型物。在低维结构中，硼化学仍然更有趣，因为具有几个到几十个原子的硼团簇有利于平面或笼状结构，在构象和电子结构方面与它们的碳类似物相似。硼和碳之间的相似性引发了一个问题，即是否存在稳定的二维（2D）硼，作为一个概念前体，其他硼纳米结构可能从它构建。在这里，我们综述了实现硼原子层的当前理论和实验进展。首先描述了十年来对硼团簇的尺寸依赖性结构的理解，然后介绍了理论如何在将硼团簇外推到 2D 形式方面发挥作用，从自由状态到衬底上的状态，以及探索它们的合成的实际途径，最近终于在实验上实现了。虽然已经揭示了 2D 硼具有异常的力学、电子和化学性质，但由于缺乏从衬底转移和高质量样品的控制合成的途径，其在实际应用中的潜力在很大程度上受到阻碍。
