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High-Performance NO2 Gas Sensing of Ultra-Small ZnFe2O4 nanoparticles Based on Surface Charge Transfer

Abstract

Monitoring the concentration of NO2 could effectively protect the health of human being and environment from the damage of NO2 emission and leaking. However, the high sensing performances (e.g. high response, fast response and recovery time, excellent selectivity, and low operating temperature) of NO2 gas sensor still remain a considerable challenge. Herein, to address above issues, pure ultra-small ZnFe2O4 nanoparticles, which exhibited outstanding selectivity to NO2 molecules, were successfully synthesized via a typical one-step hydrothermal synthetic procedure. We find that ZnFe2O4 based sensor exhibits ultra-high response (Rgas/Rair = 247.7), fast response time (Tres. = 6.5 s) and recovery time (Trec. = 11 s) toward 10 ppm NO2 at a low operating temperature of 125 ℃, which are well superior to the vast majority of NO2 semiconducting sensors, and more importantly, it has barely been reported that the spinel structure material based sensor presented such excellent sensing performances for NO2. Ex-situ photoluminescence characterization was applied to reveal the gas sensing mechanism based on charge transfer. Furthermore, to deeply investigate the experimental phenomena, adsorption energy and charge transfer between gas molecules and ZnFe2O4 based sensor were explored by the 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 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 theoretical calculation, the existence of oxygen vacancy can enhance the adsorption energy and charge transfer between the surface of ZnFe2O4 and NO2 molecules. Significantly, our results not only provided fundamental studies of 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.

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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, Accepted Manuscript

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    High-Performance NO2 Gas Sensing of Ultra-Small ZnFe2O4 nanoparticles Based on Surface Charge Transfer

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

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