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Since the discovery of two-dimensional (2D) single-layer carbon material graphene, its excellent ultra-thin electrical and thermal conductivity, high electron mobility, and quantum Hall effect have led to a wide range of research interests and applied research. At the same time, other 2D ultra-thin crystals (such as metal sulfides, metal oxides, and boron nitride (BN)) have also received close attention in recent years. Due to the quantum confinement effect, these crystals exhibit special optical, electrical and magnetic properties that are different from their bulk materials, and therefore have broad application prospects in fields such as catalysis, energy storage, and topological insulators.
The research group of the Institute of Nanotechnology and Nanobionics of the Chinese Academy of Sciences, Wang Qianbin, has made sustained progress in the preparation of metal chalcogenides and the regulation of their optical properties. Next-infrared fluorescent Ag2S quantum dots (J. Am. Chem. Soc., 2010, 132 (5), 1470-1471), near-infrared-blue dual fluorescent Ag2S-ZnS heterojunction (Angew. Chem. Int. Ed 2011, 50, 7115-7118) and orange-near-infrared blue fluorescent Mn-doped Ag2S-ZnS heterojunctions (Chem. Mater. 2012, 24, 2407-2413), they began to pay attention to the synthesis of metal selenides. . Recently, they have made new progress in the preparation of SnSe ultrathin monolayer nanosheets. SnSe is considered to be an excellent solar cell material due to its narrow bandgap and matching with the optimal solar spectrum.
Using liquid-phase synthesis methods, they developed a method for single-step preparation of single-layer, single-crystalline SnSe nanosheets. Using selenium dioxide as the source of selenium and phenanthroline as the morphology control agent, SnSe monocrystalline nanoplates with a thickness of ~1 nm were obtained in high yield in the presence of solvent and reducing agent oleylamine. It has been found that the presence of o-phenanthroline plays a key role in the preparation of ultra-thin nanosheets and is believed to effectively attach to the (100) crystal plane of SnSe and inhibit its further growth during the reaction. Control experiments showed that if there is no addition of phenanthroline, a three-dimensional flower-like structure assembled from thicker sheet-like SnSe will be obtained. Since it was the first chemical wet process to produce high-quality SnSe monolayers, they further investigated their photoelectric response characteristics, and the results showed that the switching ratio was superior to the previously reported data. The related results were published in J. Am. Chem. Soc., 2013, 135(4), 1213–1216.
This work has received strong support from the "Hundred Talents Program" of the Chinese Academy of Sciences, the pilot project of the Chinese Academy of Sciences, the National Natural Science Foundation, the Natural Science Foundation of Jiangsu Province, and the Ministry of Science and Technology.
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