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Issue 10, 2019
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High-performance NO2-gas sensing of ultrasmall ZnFe2O4 nanoparticles based on surface charge transfer

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Abstract

Monitoring the concentration of NO2 could effectively protect the health of human beings and the environment from damage from NO2 emissions and leakage. However, the high sensing performances (e.g., high response, fast response and recovery time, excellent selectivity, and low operating temperature) of the current NO2-gas sensors still remain a considerable challenge. Herein, to address the above-stated issues, pure ultrasmall ZnFe2O4 nanoparticles, which have exhibited outstanding selectivity to NO2 molecules, were successfully synthesized via a typical one-step hydrothermal synthetic procedure. We found that our ZnFe2O4-based sensor exhibited an ultrahigh response (Rgas/Rair = 247.7) and fast response time (Tres. = 6.5 s) and recovery time (Trec. = 11 s) toward 10 ppm NO2 at a low operating temperature of 125 °C, which are superior to the vast majority of NO2 semiconducting sensors, and more importantly, a sensor based on spinel structure materials presenting such excellent sensing performances for NO2 has barely been reported before. Ex situ photoluminescence characterization was applied to reveal the gas sensing mechanism based on charge transfer. Furthermore, to deeply investigate the experimental phenomena, the adsorption energy and charge transfer between gas molecules and the ZnFe2O4-based sensor were explored by density functional theory calculation and Bader charge analysis in this work. As a result, the theory calculations demonstrated that NO2 molecules have a larger negative adsorption energy (−1.32 eV) and that 0.35 electrons transfer from Zn and Fe atoms of the ZnFe2O4 to NO2 molecules during the process of NO2 adsorption. Also, according to the results of our theoretical calculations, the existence of an oxygen vacancy can also enhance the adsorption energy and charge transfer between the surface of ZnFe2O4 and NO2 molecules. Significantly, our results not only provide the results from fundamental studies elaborating the gas sensing mechanism based on charge transfer but may pave the way for the commercial application of spinel structure materials in gas-sensing fields.

Graphical abstract: High-performance NO2-gas sensing of ultrasmall ZnFe2O4 nanoparticles based on surface charge transfer

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Publication details

The article was received on 17 Dec 2018, accepted on 03 Feb 2019 and first published on 05 Feb 2019


Article type: Paper
DOI: 10.1039/C8TA12168K
Citation: J. Mater. Chem. A, 2019,7, 5539-5551

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    High-performance NO2-gas sensing of ultrasmall ZnFe2O4 nanoparticles based on surface charge transfer

    K. Li, Y. Luo, B. Liu, L. Gao and G. Duan, J. Mater. Chem. A, 2019, 7, 5539
    DOI: 10.1039/C8TA12168K

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