Chen Pin-Ru, Fu Hsuan-Wei, Yang Shu-Meng, Lu Kuo-Chang
Department of Materials Science and Engineering, National Cheng Kung University, Tainan 701, Taiwan.
Core Facility Center, National Cheng Kung University, Tainan 701, Taiwan.
Nanomaterials (Basel). 2022 Apr 4;12(7):1208. doi: 10.3390/nano12071208.
Owing to its unique and variable lattice structure and stoichiometric ratio, tungsten oxide is suitable for material modification; for example, doping is expected to improve its catalytic properties. However, most of the doping experiments are conducted by hydrothermal or multi-step synthesis, which is not only time-consuming but also prone to solvent contamination, having little room for mass production. Here, without a catalyst, we report the formation of high-crystallinity manganese-doped and potassium-doped tungsten oxide nanowires through chemical vapor deposition (CVD) with interesting characterization, photocatalytic, and gas sensing properties. The structure and composition of the nanowires were characterized by transmission electron microscopy (TEM) and energy-dispersive spectroscopy (EDS), respectively, while the morphology and chemical valence were characterized by scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS), respectively. Electrical measurements showed that the single nanowires doped with manganese and potassium had resistivities of 1.81 × 0 Ω·m and 1.93 × 10 Ω·m, respectively. The doping contributed to the phase transition from monoclinic to metastable hexagonal for the tungsten oxide nanowires, the structure of which is known for its hexagonal electron channels. The hexagonal structure provided efficient charge transfer and enhanced the catalytic efficiency of the tungsten oxide nanowires, resulting in a catalytic efficiency of 98.5% for the manganese-doped tungsten oxide nanowires and 97.73% for the potassium-doped tungsten oxide nanowires after four hours of degradation of methylene blue. Additionally, the gas sensing response for 20 ppm of ethanol showed a positive dependence of doping with the manganese-doped and potassium-doped responses being 14.4% and 29.7%, respectively, higher than the pure response at 250 °C. The manganese-doped and potassium-doped tungsten oxide nanowires are attractive candidates in gas sensing, photocatalytic, and energy storage applications, including water splitting, photochromism, and rechargeable batteries.
由于其独特且可变的晶格结构和化学计量比，氧化钨适用于材料改性；例如，掺杂有望改善其催化性能。然而，大多数掺杂实验是通过水热法或多步合成进行的，这不仅耗时，而且容易受到溶剂污染，大规模生产的空间很小。在此，我们报道了在无催化剂的情况下，通过化学气相沉积（CVD）形成了具有高结晶度的锰掺杂和钾掺杂氧化钨纳米线，其具有有趣的表征、光催化和气体传感特性。纳米线的结构和组成分别通过透射电子显微镜（TEM）和能量色散光谱（EDS）进行表征，而形态和化学价分别通过扫描电子显微镜（SEM）和X射线光电子能谱（XPS）进行表征。电学测量表明，掺杂锰和钾的单根纳米线的电阻率分别为1.81×10⁰Ω·m和1.93×10Ω·m。掺杂导致氧化钨纳米线从单斜相转变为亚稳六方相，其结构以六方电子通道而闻名。六方结构提供了高效的电荷转移并提高了氧化钨纳米线的催化效率，在亚甲基蓝降解4小时后，锰掺杂氧化钨纳米线的催化效率为98.5%，钾掺杂氧化钨纳米线的催化效率为97.73%。此外，对于20 ppm乙醇的气敏响应显示出掺杂的正相关性，在250℃时，锰掺杂和气敏响应为14.4%，钾掺杂为29.7%，分别高于纯响应。锰掺杂和钾掺杂的氧化钨纳米线在气体传感、光催化和能量存储应用中是有吸引力的候选材料，包括水分解、光致变色和可充电电池。
