Rosentsveig R, Sreedhara M B, Sinha S S, Kaplan-Ashiri I, Brontvein O, Feldman Y, Pinkas I, Zheng K, Castelli I E, Tenne R
Department of Molecular Chemistry and Materials Science, Weizmann Institute of Science, Rehovot 7610001, Israel.
Solid State and Structural Chemistry Unit, Indian Institute of Science, Bengaluru 560012, India.
Inorg Chem. 2023 Nov 6;62(44):18267-18279. doi: 10.1021/acs.inorgchem.3c02903. Epub 2023 Oct 24.
The synthesis of complex new nanostructures is challenging but also bears the potential for observing new physiochemical properties and offers unique applications in the long run. High-temperature synthesis of ternary WSeS (denoted as WSSe) nanotubes in a pure phase and in substantial quantities is particularly challenging, requiring a unique reactor design and control over several parameters, simultaneously. Here, the growth of WSSe nanotubes with the composition 0 ≤ < 1 from WO nanowhiskers in an atmospheric chemical vapor deposition (CVD) flow reactor is investigated. The oxide precursor powder is found to be heavily agglomerated, with long nanowhiskers decorating the outer surface of the agglomerates and their core being enriched with oxide microcrystallites. The reaction kinetics with respect to the chalcogen vapors varies substantially between the two kinds of oxide morphologies. Insights into the chemical reactivity and diffusion kinetics of S and Se within WO nanowhishkers and the micro-oxide crystallites were gained through detailed microscopic, spectroscopic analysis of the reaction products and also through density functional theory (DFT) calculations. For safety reasons, the reaction duration was limited to half an hour each. Under these circumstances, the reaction was completed for some 50% of the nanotubes and the other half remained with thick oxide core producing new WO@WSSe core-shell nanotubes. Furthermore, the selenium reacted rather slowly with the WO nanowhiskers, whereas the more ionic and smaller sulfur atoms were shown to diffuse and react faster. The yield of the combined hollow and core-shell nanotubes on the periphery of the agglomerated oxide was very high, approaching 100% in parts of the reactor boat. The nanotubes were found to be very thin (∼80% with a diameter <40 nm). The optical properties of the nanotubes were studied, and almost linear bandgap modulation was observed with respect to the selenium content in the nanotubes. This investigation paves the way for further scaling up the synthesis and for a detailed study of the different properties of WSSe nanotubes.
复杂新型纳米结构的合成具有挑战性，但从长远来看，也具有观察新的物理化学性质的潜力，并提供独特的应用。在纯相中大量合成三元WSeS（记为WSSe）纳米管极具挑战性，需要独特的反应器设计并同时控制多个参数。在此，研究了在常压化学气相沉积（CVD）流动反应器中，由WO纳米晶须生长组成0≤x＜1的WSSe纳米管。发现氧化物前驱体粉末严重团聚，长纳米晶须装饰着团聚体的外表面，其核心富含氧化物微晶。两种氧化物形态之间，硫属元素蒸气的反应动力学有很大差异。通过对反应产物进行详细的微观和光谱分析以及密度泛函理论（DFT）计算，深入了解了S和Se在WO纳米晶须和微氧化物微晶中的化学反应性和扩散动力学。出于安全考虑，反应持续时间限制为每次半小时。在这种情况下，约50%的纳米管反应完成，另一半仍保留厚氧化物核心，从而产生新的WO@WSSe核壳纳米管。此外，硒与WO纳米晶须反应相当缓慢，而更具离子性且较小的硫原子扩散和反应更快。在团聚氧化物周边，空心和核壳纳米管的组合产率非常高，在反应舟的部分区域接近100%。发现纳米管非常细（约80%的直径＜40nm）。研究了纳米管的光学性质，观察到纳米管的带隙调制几乎与硒含量呈线性关系。这项研究为进一步扩大合成规模以及详细研究WSSe纳米管的不同性质铺平了道路。
