2D Molybdenum Carbide MXenes for Enhanced Selective Detection of Humidity in Air. Issue 52 (19th October 2021)

• Record Type: Journal Article
• 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.
• Is Part Of: Advanced materials. Volume 33:Issue 52(2021)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2021-10-19
• Subjects: alcohol -- chemiresistor -- DFT -- humidity -- Mo 2CTx -- multisensor array -- vdW‐DF; Materials -- Periodicals; Chemical vapor deposition -- Periodicals; 620.11
• DOI: 10.1002/adma.202104878
• Languages: English
• ISSNs: 0935-9648

Abstract

Abstract: 2D transition metal carbides and nitrides (MXenes) open up novel opportunities in gas sensing with high sensitivity at room temperature. Herein, 2D Mo2 CT x flakes with high aspect ratio are successfully synthesized. The chemiresistive effect in a sub‐µm MXene multilayer for different organic vapors and humidity at 10 1 –10 4 ppm in dry air is studied. Reasonably, the low‐noise resistance signal allows the detection of H2 O down to 10 ppm. Moreover, humidity suppresses the response of Mo2 CT x 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 –10 6 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 Mo2 CT x chemiresistance is mainly originating from electron transport through interflake potential barriers with heights up to 0.2 eV. Density functional theory calculations, elucidating the Mo2 C surface interaction with organic analytes and H2 O, explain the experimental data as an energy shift of the density of states under the analyte's adsorption which induces increasing electrical resistance. Abstract : 2D Mo2 CT x 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 H2 O down to 10 ppm, with humidity suppressing the Mo2 CT x response to organic analytes due to the blocking of adsorption active sites.