Zafari Mohsen, Shariatmadar Tehrani Fatemeh, Hosseini Shokouh Seyed Hossein, Popov Alexey, Kordas Krisztian
Faculty of Physics, Semnan University P.O. Box 35195-363 Semnan Iran
Microelectronics Research Unit, Faculty of Information Technology and Electrical Engineering, University of Oulu P.O. Box 4500 FIN-90014 Oulu Finland.
RSC Adv. 2025 Jan 22;15(3):2099-2105. doi: 10.1039/d4ra07112c. eCollection 2025 Jan 16.
In this study, the effect of feedstock concentration on the synthesis of WO nanostructures in a one-step hydrothermal process was investigated. According to our experiments, when titrating aqueous NaWO·2HO with HCl solutions of different concentrations to a constant pH of 1.5, after identical hydrothermal treatments at 180 °C, the morphology, crystal size and phase composition as well as the optical properties of the products could be tuned. Furthermore, by applying NaSO in the precursor solution, we get a further degree of freedom to alter the structural and optical properties of the products. The precursor concentration dependent optical band gap energy values (that vary from ∼2.5 eV to ∼2.9 eV) are in good agreement with the associated hexagonal (from 32.7% to 65.5%) and orthorhombic (from 67.3% to 34.5%) phases of nanostructured tungsten oxide products. The calculated Urbach energies can be well explained by the oxygen deficient crystals. The latter is also coherent with measured photoluminescence (multiple peaks between 400 and 580 nm) that indicate abundant defect states in the tungsten oxide products.
在本研究中，研究了原料浓度对一步水热法合成WO纳米结构的影响。根据我们的实验，当用不同浓度的HCl溶液将NaWO·2HO水溶液滴定至恒定pH值1.5时，在180℃进行相同的水热处理后，产物的形貌、晶体尺寸和相组成以及光学性质均可得到调控。此外，通过在前驱体溶液中加入NaSO，我们获得了进一步改变产物结构和光学性质的自由度。前驱体浓度依赖的光学带隙能量值（从约2.5 eV到约2.9 eV变化）与纳米结构氧化钨产物的相关六方相（从32.7%到65.5%）和正交相（从67.3%到34.5%）良好吻合。计算得到的乌尔巴赫能量可以用缺氧晶体很好地解释。后者也与测得的光致发光（400至580 nm之间的多个峰）一致，这表明氧化钨产物中存在大量缺陷态。
