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Issue 46, 2018
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Molybdenum carbide chemical sensors with ultrahigh signal-to-noise ratios and ambient stability

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Abstract

Herein, we present a demonstration of the usability of the chemical sensing properties of transition metal carbides (TMCs) as gas sensing channels. Two phases of nanostructured molybdenum carbide (α-MoC1−x and β-Mo2C) with high porosities were perfectly synthesized by a temperature-programmed reduction (TPR) method, and they showed distinct metallic characteristics due to different density of states (DOS) localization status. The molybdenum carbide sensors showed novel gas sensing characteristics which have not been shown by previous typical sensing materials: predominantly, an unprecedentedly high signal-to-noise ratio (SNR) with the ability to detect the ppb levels of NH3 and NO2 was achieved, which is attributed to a combination of high electrical conductivity and superior catalytic properties. In addition to high sensitivity, unlike previous channel materials, the molybdenum carbide sensors showed very high ambient stability. The electrical conductivity and sensing performance are well preserved for half-year ambient exposure without any oxidation or degradation of channel materials, due to the good corrosion resistance and low chemical reactivity of molybdenum carbides. In addition, a versatile gas sensing response is observed according to the crystal phase of molybdenum carbides due to the distinct DOS of α-MoC1−x and β-Mo2C. We believe that this observation of new chemical sensing materials can shed light on the superior potential of TMCs for highly sensitive and stable low-power operating internet-of-things (IoT) sensors. In addition, owing to their ultra-high chemical stability and high melting temperature, TMCs can be utilized as channel materials for sensors in harsh operating conditions.

Graphical abstract: Molybdenum carbide chemical sensors with ultrahigh signal-to-noise ratios and ambient stability

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Publication details

The article was received on 25 Jul 2018, accepted on 19 Oct 2018 and first published on 22 Oct 2018


Article type: Paper
DOI: 10.1039/C8TA07168C
Citation: J. Mater. Chem. A, 2018,6, 23408-23416

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    Molybdenum carbide chemical sensors with ultrahigh signal-to-noise ratios and ambient stability

    S. Cho, J. Y. Kim, O. Kwon, J. Kim and H. Jung, J. Mater. Chem. A, 2018, 6, 23408
    DOI: 10.1039/C8TA07168C

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