Soltabayev Baktiyar, Yergaliuly Gani, Ajjaq Ahmad, Beldeubayev Askhat, Acar Selim, Bakenov Zhumabay, Mentbayeva Almagul
National Laboratory Astana, Nazarbayev University, Nur-Sultan 010000, Kazakhstan.
L.N. Gumilyov Eurasian National University, Nur-Sultan 010000, Kazakhstan.
ACS Appl Mater Interfaces. 2022 Sep 14;14(36):41555-41570. doi: 10.1021/acsami.2c10055. Epub 2022 Aug 29.
In this study, Ti-doped ZnO films with flower-rod-like nanostructures were synthesized by the successive ionic layer adsorption and reaction (SILAR) method for enhanced NO gas-sensing applications. The stoichiometric ratio of Ti in the host ZnO lattice was confirmed by atomic absorption and energy-dispersive X-ray spectroscopies. All of the synthesized films exhibited a pure wurtzite hexagonal structure that seemed to deteriorate at high Ti doping contents as was manifested by the measured X-ray diffraction patterns. Scanning electron microscopy images of ZnO revealed the coexistence of porous flower- and rod-like structures, which became finer, denser, and more compact with Ti doping. By UV-vis measurements, the transmittance of the synthesized pure ZnO thin film in the visible region (∼75%) increased by about 10% with Ti doping, and the energy band gap seemed to decrease up to some limit of Ti content. Among the fabricated sensors (based on pure ZnO, 1% Ti-doped, 3% Ti-doped, and 5% Ti-doped ZnO films), the best sensing performance was observed for the 1% Ti-doped ZnO film. At first, this was associated with its high density of oxygen vacancies present on the surface of the film and ionized oxygen vacancies present in the ZnO lattice (confirmed, respectively, by X-ray photoelectron and photoluminescence spectroscopies). Nonetheless, this may also be due to its increased crystallinity (confirmed by X-ray diffraction and photoluminescence spectroscopy), high area-to-volume ratio (confirmed by scanning electron microscopy images), high specific surface area (confirmed by Brunauer-Emmett-Teller measurements) as well as high mobility and carrier concentration (confirmed by Hall measurements). The sensor was highly selective to NO gas and showed notable stability as well as very short response and recovery times, which makes it eligible for the early detection of any indoor or outdoor NO gas leakages.
在本研究中，采用连续离子层吸附与反应（SILAR）法合成了具有花棒状纳米结构的Ti掺杂ZnO薄膜，以增强其对NO气体的传感应用。通过原子吸收光谱和能量色散X射线光谱确定了主体ZnO晶格中Ti的化学计量比。所有合成薄膜均呈现出纯纤锌矿六方结构，如测量的X射线衍射图谱所示，在高Ti掺杂含量下该结构似乎会恶化。ZnO的扫描电子显微镜图像显示多孔花状和棒状结构共存，随着Ti掺杂，这些结构变得更细、更致密且更紧凑。通过紫外可见光谱测量，合成的纯ZnO薄膜在可见光区域的透过率（约75%）随着Ti掺杂增加了约10%，并且能带隙似乎在Ti含量达到一定限度之前会减小。在所制备的传感器（基于纯ZnO、1% Ti掺杂、3% Ti掺杂和5% Ti掺杂的ZnO薄膜）中，1% Ti掺杂的ZnO薄膜表现出最佳的传感性能。起初，这与其薄膜表面存在的高密度氧空位以及ZnO晶格中存在的电离氧空位有关（分别通过X射线光电子能谱和光致发光光谱证实）。尽管如此，这也可能归因于其结晶度的提高（通过X射线衍射和光致发光光谱证实）、高的面积体积比（通过扫描电子显微镜图像证实）、高比表面积（通过布鲁诺尔-埃米特-泰勒测量证实）以及高迁移率和载流子浓度（通过霍尔测量证实）。该传感器对NO气体具有高度选择性，表现出显著的稳定性以及非常短的响应和恢复时间，这使其适用于早期检测任何室内或室外的NO气体泄漏。
