Controllable preparation of ultrathin MXene nanosheets and their excellent QCM humidity sensing properties enhanced by fluoride doping

• Published in: Mikrochimica acta (1966) Vol. 188; no. 3; p. 81
• Main Authors: Li, Runlong, Fan, Yu, Ma, Zhiheng, Zhang, Dan, Liu, Yiming, Xu, Jiaqiang
• Format: Journal Article
• Language: English
• Published: Vienna Springer Vienna 01.03.2021; Springer; Springer Nature B.V
• Subjects: Analysis; Analytical Chemistry; Characterization and Evaluation of Materials; Chemistry; Chemistry and Materials Science; Density functional theory; Doping; Fluorides; Graphene; Humidity; Immersion coating; Liquid phases; Microbalances; Microengineering; Morphology; MXenes; Nanochemistry; Nanosheets; Nanotechnology; Original Paper; Quartz crystals; Recovery time; Selectivity; Sensors; Stability; Humidity sensor; Quartz crystal microbalance (QCM); Humidity sensing mechanism; MXene nanosheets; 2D materials
• ISSN: 0026-3672; 1436-5073
• DOI: 10.1007/s00604-021-04723-2

A 2D ultrathin MXene nanosheet was prepared under controlled conditions and employed as a sensitive film to construct a QCM (quartz crystal microbalance) humidity sensor by a dip coating method. The MXene nanosheets were obtained by dislodging the element A from the MAX phase by a facile liquid phase etching method. The morphology and composition of the MXene nanosheets were characterized by means of a number of advanced instruments. It was found that the sample is an ultrathin graphene-like nanosheet. The sensing test results showed that the sensor has a 12.8 Hz/% RH sensitivity, 6 s and 2 s (@ 90%) response/recovery time, maximum humidity hysteresis of 1.16% RH, good stability, and selectivity. Finally, the enhanced humidity response mechanism of the MXene nanosheets was explored by density-functional theory (DFT) calculation and experimental verification. The DFT simulation together with comparison of fluoride-free sample revealed that F elements on the surface of the MXene nanosheets play a more important role in improving humidity responses than OH groups. The results present a new strategy to enhance humidity sensing performance of sensing materials by F − doping or decoration. Thus, the sensor has bright potential for humidity sensing. Graphical abstract