We have prepared nanocrystals of MoS2 across a range of length scales by heating single crystals of the molecular precursor (NH4)2Mo3S13·H2O. Rod-shaped crystals of the polysulfide precursor retain their original morphology after heating at temperatures up to 1000 °C and undergo complete conversion to MoS2 while acting as a template for the confined formation of MoS2 nanocrystals. This solid state transformation proceeds with the release of gaseous species without blowing the crystals apart and leads to formation of pores embedded into a nanocrystalline assembly of the templated nano-MoS2. The obtained assemblies of MoS2 nanocrystals have the exact same shape of the original rod-shaped (NH4)2Mo3S13·H2O crystals indicative of a pseudomorphic shape-retentive process. Such crystal-shaped nanocrystal assemblies show electrical conductivity values similar to a bulk MoS2 single crystal with electron carrier concentration of 1.5 × 1014 cm–3 and mobility of 7 cm2/(V s). The nanocrystals of MoS2 were grown at temperatures ranging from 450 to 1000 °C, and the sizes, shapes, morphologies, and their orientations can be engineered as a function of heating rate, soaking time, and temperature. These findings suggest a unique process for constrained templated nanocrystal growth from an organized molecular precursor structure with control of bulk morphology, size distribution, and orientation of nanocrystallites.
我们通过加热分子前驱体 (NH4)2Mo3S13-
H2O 的单晶,制备出了不同长度范围的 MoS2 纳米晶体。多
硫化物前驱体的棒状晶体在加热至 1000 ℃ 时仍保持原有形态,并完全转化为 MoS2,同时成为密闭形成 MoS2 纳米晶体的模板。在这种固态转化过程中,会释放出气态物质,而不会使晶体炸裂,从而形成嵌入模板化纳米 MoS2 纳米晶体组装体中的孔隙。所获得的 MoS2 纳米晶体集合体与原始棒状 (NH4)2Mo3S13- 晶体的形状完全相同,表明这是一种假形态保形过程。这种晶体状的纳米晶体集合体显示出与块状 MoS2 单晶类似的电导率值,电子载流子浓度为 1.5 × 1014 cm-3,迁移率为 7 cm2/(V s)。MoS2 纳米晶体的生长温度范围为 450 至 1000 °C,其尺寸、形状、形态及其取向可作为加热速率、浸泡时间和温度的函数进行设计。这些发现表明,从有组织的分子前驱体结构中生长出受约束的模板化纳米晶体是一种独特的过程,可以控制纳米晶体的体形、尺寸分布和取向。