MOF-derived Fe2O3: Phase control and effects of phase composition on gas sensing performance

•Porous Fe2O3 was prepared by heating Fe-MOF (FeFe(CN)6) templates.•Above method is effective to control the phase composition.•The phase composition significantly affects the gas sensing performance for VOCs.•Sensibility of α-Fe2O3 comes from the concentration change of free carriers.•Sensibility o...

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Bibliographic Details
Published in:Sensors and actuators. B, Chemical Chemical, 2019-08, Vol.292, p.171-179
Main Authors: Wang, Mingjing, Hou, Tianyi, Shen, Zhurui, Zhao, Xiaodong, Ji, Huiming
Format: Article
Language:English
Subjects:
Butanol
Composition effects
Detection
Gas sensing mechanism
Gas sensors
Iron oxides
Metal oxides
Metal-organic frameworks
MOF
Phase composition
Phase control
VOCs
Volatile organic compounds
α-Fe2O3
γ-Fe2O3
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Summary:•Porous Fe2O3 was prepared by heating Fe-MOF (FeFe(CN)6) templates.•Above method is effective to control the phase composition.•The phase composition significantly affects the gas sensing performance for VOCs.•Sensibility of α-Fe2O3 comes from the concentration change of free carriers.•Sensibility of γ-Fe2O3 is from transformation between γ-Fe2O3 and Fe3O4. Recently, the phase composition of a certain metal oxide has been regarded as an important factor that can significantly influence the gas sensing performance. For a better comparison, an appropriate method is necessary to control the phase composition of metal oxides. Herein, three Fe2O3 samples with different phase compositions of α-Fe2O3, γ-Fe2O3 and a mixed phase of α-Fe2O3 and γ-Fe2O3 were prepared by calcining MOF (metal-organic framework) templates at different temperatures. As-prepared Fe2O3 samples have a similar morphologic structure but quite different gas sensing properties for VOCs (volatile organic compounds). Among them, α-Fe2O3 has the smallest specific surface area, but the highest response toward n-butanol. It is indicated that α-Fe2O3 and γ-Fe2O3 have different gas sensing mechanisms. The sensitivity of α-Fe2O3 comes from the concentration change of free carriers within the surface region. Differently, the transformation between γ-Fe2O3 and Fe3O4 determines the response of γ-Fe2O3. The findings can be used in the design of Fe2O3 gas sensing materials in the future.
ISSN:0925-4005
1873-3077
DOI:10.1016/j.snb.2019.04.124