S. Ghazal

Preparation of pure and Se/WO3-NRDs was successfully carried out using the sol-gel route. In a typical process, 3.30 g Na2WO4.2H2O was dissolved in 80 mL distilled water, and an appropriate amount of Na2SeO3 (0.057, 0.095, or 0.133 g) was dissolved in 20 mL distilled water to prepare 3, 5, or 7% doping solution. The Na2SeO3 salt solution was added drop by drop to the Na2WO4 salt solution under constant stirring. In the next step, 0.25 g chitosan powder as stabilizer was dissolved in 25 ml 5% acetic acid solution at ambient temperature, and it was added drop by drop to the mixed salt solution. Then the pH of the mixture was lowered to 1.5 by dropwise addition of HCl, 2.0 M, and the obtained gel stirred for 16 h at ambient temperature. The powder produced was filtered off and carefully washed five times with distilled water, and the last time, it was ethanol. The filtrate was dried in an oven at 70 °C overnight and then calcined at 550 °C for two hours. The pure sample was prepared by dissolving the same amount of Na2WO4.2H2O in 100 mL of distilled water without the addition of Na2SeO3, with the same procedure. The UV-Vis spectrophotometer (Perkin-Elmer, Lambda 365) in the 200-800 nm range was used for the optical evaluation. FESEM/EDX (Zeiss, Sigma 300-HV) and PXRD (Bruker, D8-Advance) analysis were used to investigate the prepared samples' morphology, surface composition, and crystal structures. The FT-IR (Thermo Nicolet, AVATAR 370), and Raman (Avantes) were also used to characterize the samples.本研究采用溶胶-凝胶法成功制备了纯相三氧化钨以及硒掺杂三氧化钨纳米棒（Se/WO3-NRDs）。典型制备流程如下：称取3.30 g二水合钨酸钠（Na₂WO₄·2H₂O）溶于80 mL蒸馏水中；另分别称取0.057 g、0.095 g、0.133 g亚硒酸钠（Na₂SeO₃），各溶于20 mL蒸馏水中，制备得到掺杂量为3%、5%、7%的掺杂液。在持续搅拌条件下，将亚硒酸钠盐溶液逐滴加入至钨酸钠盐溶液中。下一步，于室温下将0.25 g作为稳定剂的壳聚糖粉末溶于25 mL 5%乙酸溶液中，随后将该溶液逐滴加入至上述混合盐溶液内。通过逐滴添加2.0 mol/L盐酸（HCl）将混合体系的pH值调至1.5，将所得凝胶于室温下搅拌16 h。将生成的粉末过滤分离，并用蒸馏水仔细洗涤五次，最后一次洗涤采用乙醇。将滤饼置于70 ℃烘箱中干燥过夜，随后于550 ℃下煅烧2 h。纯相样品的制备流程一致，仅需将等量的二水合钨酸钠溶于100 mL蒸馏水中，且不添加亚硒酸钠。 采用紫外-可见分光光度计（UV-Vis spectrophotometer，珀金埃尔默（Perkin-Elmer）Lambda 365型）在200~800 nm波长范围内开展光学性能表征。采用场发射扫描电子显微镜/能量色散X射线光谱仪（FESEM/EDX，蔡司（Zeiss）Sigma 300-HV型）与X射线粉末衍射仪（PXRD，布鲁克（Bruker）D8-Advance型）对制备样品的形貌、表面组成及晶体结构进行表征分析。此外，采用傅里叶变换红外光谱仪（FT-IR，赛默飞尼高力（Thermo Nicolet）AVATAR 370型）与拉曼光谱仪（Avantes型）对样品进行表征。