2D Molybdenum Carbide MXenes for Enhanced Selective Detection of Humidity in Air

2D transition metal carbides and nitrides (MXenes) open up novel opportunities in gas sensing with high sensitivity at room temperature. Herein, 2D Mo2CTx flakes with high aspect ratio are successfully synthesized. The chemiresistive effect in a sub‐µm MXene multilayer for different organic vapors a...

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Bibliographic Details
Published in:Advanced materials (Weinheim) 2021-12, Vol.33 (52), p.e2104878-n/a
Main Authors: Pazniak, Hanna, Varezhnikov, Alexey S., Kolosov, Dmitry A., Plugin, Ilya A., Vito, Alessia Di, Glukhova, Olga E., Sheverdyaeva, Polina M., Spasova, Marina, Kaikov, Igor, Kolesnikov, Evgeny A., Moras, Paolo, Bainyashev, Alexey M., Solomatin, Maksim A., Kiselev, Ilia, Wiedwald, Ulf, Sysoev, Victor V.
Format: Article
Language:English
Subjects:
Adsorption
alcohol
chemiresistor
Density functional theory
DFT
Electron transport
Gas sensors
High aspect ratio
Humidity
Metal carbides
Mo 2CT x
Molybdenum carbide
Multilayers
multisensor array
MXenes
Room temperature
Transfer functions
Transition metals
vdW‐DF
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Summary:2D transition metal carbides and nitrides (MXenes) open up novel opportunities in gas sensing with high sensitivity at room temperature. Herein, 2D Mo2CTx flakes with high aspect ratio are successfully synthesized. The chemiresistive effect in a sub‐µm MXene multilayer for different organic vapors and humidity at 101–104 ppm in dry air is studied. Reasonably, the low‐noise resistance signal allows the detection of H2O down to 10 ppm. Moreover, humidity suppresses the response of Mo2CTx to organic analytes due to the blocking of adsorption active sites. By measuring the impedance of MXene layers as a function of ac frequency in the 10−2–106 Hz range, it is shown that operation principle of the sensor is dominated by resistance change rather than capacitance variations. The sensor transfer function allows to conclude that the Mo2CTx chemiresistance is mainly originating from electron transport through interflake potential barriers with heights up to 0.2 eV. Density functional theory calculations, elucidating the Mo2C surface interaction with organic analytes and H2O, explain the experimental data as an energy shift of the density of states under the analyte's adsorption which induces increasing electrical resistance. 2D Mo2CTx MXene flakes are successfully synthesized and studied on their chemiresistive effect, demonstrating an enhanced sensitivity toward water vapor at room temperature in dry air. The low‐noise resistance signal allows the detection of H2O down to 10 ppm, with humidity suppressing the Mo2CTx response to organic analytes due to the blocking of adsorption active sites.
ISSN:0935-9648
1521-4095
DOI:10.1002/adma.202104878