Mechanochemically induced sulfur doping in ZnO via oxygen vacancy formation
Mechanochemically induced sulfur doping in ZnO via oxygen vacancy formation
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DOI：
10.1039/c7cp01489a
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发表时间：
2017-06-07
影响因子：
3.3
通讯作者：
Peukert, W.
中科院分区：
文献类型：
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作者：
Daiko, Y.;Schmidt, J.;Peukert, W.
利用TurBula搅拌机和行星球磨机对纳米氧化锌进行机械应力处理，得到了纳米氧化锌颗粒的表面缺陷，并以活性氧化锌的硫掺杂为例说明了纳米氧化锌颗粒表面修饰和功能化的可能性。拉曼光谱表明，氧空位(V-O)的形成不仅发生在行星球磨机的高应力条件下，甚至在摇床混合器中的较温和的应力下也会发生。在不同应力条件下，氧化锌中空位浓度的时间演化可以用一个考虑应力个数和空位扩散的模型来描述，在摇床和行星球磨机中的应力扩散系数分别为3.7x10(-21)m(2)S(-1)和2.4x10(-20)m(2)S(-1)。V-O层的厚度估计约为1 nm。将硫脲与有缺陷的氧化锌颗粒混合，在不同温度下加热进行硫掺杂。结果表明，诱导的V-O量与硫的掺杂量呈线性关系。值得注意的是，为了定量控制硫掺杂水平，机械活化是必不可少的。高角环形暗场扫描电子显微镜(HAADF STEM)和能谱分析(EDX)的观察清楚地表明，掺杂的硫原子集中在颗粒表面。因此，通过机械力化学活化和随后的热处理，可以很容易地获得氧化锌(核)/硫化锌(壳)结构。
Surface defects of ZnO nanoparticles were induced via mechanical stressing using a Turbula shaker mixer and a planetary ball mill, and the possibilities for surface modification and functionalization of the ZnO nanoparticles were exemplified by sulfur doping of activated ZnO. Raman spectroscopy reveals that the formation of oxygen vacancies (V-O) does not only occur under high stressing conditions in a planetary ball mill but even upon rather 'mild stressing' in the shaker mixer. The temporal evolution of the vacancy concentration in ZnO stressed under different conditions can be described by a model that accounts for stress number and vacancy diffusion with diffusion coefficients of V-O of 3.7 x 10(-21) m(2) s(-1) and 2.4 x 10(-20) m(2) s(-1) for stressing in the shaker and the planetary ball mill, respectively. The thickness of the V-O layer was estimated to be about 1 nm. Thiourea was mixed with defective ZnO particles, and then heated at various temperatures for sulfur-doping. A linear relationship between the amount of induced V-O and the level of sulfur doping was found. Remarkably, mechanical activation is indispensable in order to control the level of sulfur doping quantitatively. High-angle annular dark field scanning transmission electron microscopy (HAADF STEM) observations with energy dispersive X-ray spectroscopy (EDX) analysis clearly revealed that the doped sulfur atoms are concentrated at the particle surface. Thus, ZnO (core)/ZnS (shell) structures are obtained easily via mechanochemical activation and subsequent thermal treatment.