Narrow bandgap tungsten oxide (WO3−x) nanoparticles have been synthesized by single-step plasma discharge in deionized water between two vertically pointed tungsten electrodes. Bombardment of energetic electrons on the as-formed nanoparticles in the plasma zone creates defect states. Formation of electron-rich oxygen vacancies on the crystal planes and grain boundary defects have been investigated. The peak shift and broadening in the Raman and FTIR spectra indicate the formation of oxygen vacancies and sub-stoichiometric WO3 nanoparticles. EDX analysis provides the ratio of tungsten to oxygen to be around 1:2.4. Optical bandgap has been found to be 2.15 eV, which is less than the bulk value of 2.54 eV. Observation of higher amount of defect states from TEM and XPS provides the reason for the formation of narrow bandgap tungsten oxide nanoparticles. The photocatalytic efficiency of the plasma synthesize WO3−x nanoparticles is found to be higher than that of commercial bulk and nano WO3 particles.

中文翻译：

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液体中等离子体放电氧空位诱导窄带隙氧化钨 (WO3−x) 纳米粒子的合成和表征及其光催化活性

窄带隙氧化钨 (WO3-x) 纳米粒子已通过在两个垂直指向的钨电极之间的去离子水中单步等离子体放电合成。高能电子轰击等离子体区中形成的纳米粒子会产生缺陷状态。已经研究了在晶面上形成富电子氧空位和晶界缺陷。拉曼光谱和 FTIR 光谱中的峰位移和展宽表明形成了氧空位和亚化学计量的 WO3 纳米颗粒。EDX 分析提供的钨与氧的比例约为 1:2.4。已发现光学带隙为 2.15 eV，小于体值 2.54 eV。从 TEM 和 XPS 观察到更多的缺陷态提供了形成窄带隙氧化钨纳米粒子的原因。发现等离子体合成 WO3-x 纳米颗粒的光催化效率高于商业散装和纳米 WO3 颗粒的光催化效率。