Highly sensitive and selective triethylamine gas sensor based on hierarchical radial CeO2/ZnO n-n heterojunction
Heterojunction formation has been considered as an effective way for exploring ultrahigh sensitive multi-metal oxide based gas sensors. Herein, unique hierarchical radial CeO 2 /ZnO heterostructures with excellent triethylamine (TEA) gas-sensing performance were successfully prepared via a feasible solvothermal method . The morphology, microstructure and gas-sensing performance of the composite were systematically characterized and investigated. The selective TEA gas response of the radial CeO 2 /ZnO heterostructure was increased by ten times as compared to that of pure ZnO phase, ascribing to the abundant reactive sites induced by the formation of n-n heterojunction . Furthermore, the radial CeO 2 /ZnO n-n heterojunction exhibited the best TEA gas sensitivity with R a /R g = 92.17 at an operating temperature of 200 °C, a fast response/recovery time of 29 s/23 s, and a long-term stable repeatability for at least 60 days. The excellent selectivity of CeO 2 /ZnO heterojunction for TEA sensing is also remained even when mixing with other interferent gases. The interface-dependent and enhanced TEA sensing property of CeO 2 /ZnO can be ascribed to its intriguing radial morphology, for which the CeO 2 nanoparticles located in the internal structure of the composite while the ZnO hexagonal prism grew radially outward. The well assembled hierarchical CeO 2 /ZnO n-n heterojunction with abundant accessible active sites significantly facilitate the surface reaction and diffusion of target gas molecules at the interface between CeO 2 and ZnO during gas sensing process.
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