Shuttle-like ZnO nano/microrods: Facile synthesis, optical characterization and high formaldehyde sensing properties |
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Authors: | Lexi Zhang Jianghong Zhao Jianfeng ZhengLi Li Zhenping Zhu |
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Affiliation: | a State Key Laboratory of Coal Conversion, Institute of Coal Chemistry, Chinese Academy of Sciences, Taoyuan South Road 27, Taiyuan 030001, Shanxi, People's Republic of China b Graduate University of Chinese Academy of Sciences, Beijing 100039, People's Republic of China |
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Abstract: | Shuttle-like ZnO nano/microrods were successfully synthesized via a low temperature (80 °C), “green” (without any organic solvent or surfactant) and simple hydrothermal process in the solution of zinc chloride and ammonia water. X-ray diffraction and Raman spectroscopy indicated that the ZnO nano/microrods are a well-crystallized hexagonal wurtzite structure. Yet photoluminescence analysis showed that abundant intrinsic defects (52.97% electron donor defects and 45.49% electron acceptor defects) exist on the surface of ZnO crystals. Gas sensors based on the shuttle-like ZnO nano/microrods exhibited high sensitivity, rapid response-recovery and good selectivity to formaldehyde in the range of 10-1000 ppm at an optimum operating temperature of 400 °C. Through applying linear fitting to the plot of sensitivity versus formaldehyde concentration in logarithmic forms, the chemisorbed oxygen species on the ZnO surface were found to be O2− (highly active among O2, O2− and O− species). Notably, formaldehyde can be easily distinguished from acetaldehyde with a selectivity of about 3. The high formaldehyde sensitivity is mainly attributed to the synergistic effect of abundant electron donor defects (52.97%) and highly active oxidants (surface adsorbed O2− species) co-existed on the surfaces of ZnO. |
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Keywords: | ZnO nano/microrods Photoluminescence Formaldehyde sensor Defects Oxygen species |
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