Two-Dimensional MoS₂ for Resonant-Gravimetric Detection of Ppb-Level Formaldehyde

Abstract

The development of formaldehyde (HCHO) gas sensors with high sensitivity, good selectivity, and fast response at room temperature is an important research topic. The resonant microcantilever, with high sensitivity, easy batch manufacturing, and integration, generates sensing signals based on the relationship between the frequency and the mass addition of the adsorbed molecules and shows good application potential in HCHO detection. Herein, we report two species of MoS 2 nanosheets (NSs) with 1T and 2H phases as sensitive materials to construct high-performance HCHO resonant cantilever sensors. The 2H-MoS 2 gas sensors show better sensitivity toward HCHO compared to the 1T-MoS 2 gas sensor. Specifically, the 2H-MoS 2 sensor displayed a high sensitivity (Hz) of 13.6−1 ppm HCHO at room temperature, with high selectivity, low limit of detection (10 ppb), and good humidity resistance. The effect of phase structures on the sensing performance was studied by in situ characterizations, thermodynamic analysis, and density functional theory calculations. The good sensing ability could be attributed to the abundant active sites induced by the surface defects, suitable adsorption strength, and the outstanding thermodynamic performance of the 2H-MoS 2 . The combination of two-dimensional (2D) nanosheet and microcantilever sensors provides a new direction for developing a high-performance room-temperature gas sensor in the future.

Solution-Processable and Printable Two-Dimensional Transition Metal Dichalcogenide Inks

“…376 Formaldehyde (HCHO) sensors have also been fabricated using inkjet-printed MoS 2 thin films (Figure 21c). 364 surface and lead to good sensing selectivity over other gases. Also, they claimed that 2H-MoS 2 crystal has more surface defects and active sites than 1T-MoS 2 , thus resulting in higher sensitivity (as indicated by resonant frequency shift of microcantilever) and lower detection limit (10 ppb) toward HCHO at room temperature (Figure 21d).…”

“…(d) Sensing performance (as indicated by frequency shift) of 2H-MoS 2 and 1T-MoS 2 to various gases. (c, d) Reproduced with permission from ref . Copyright 2022 American Chemical Society.…”

“…Formaldehyde (HCHO) sensors have also been fabricated using inkjet-printed MoS 2 thin films (Figure c) . Wang et al found that the S vacancies and Mo defects of the 2H-MoS 2 surface form O–H bonds and Mo–O bonds with O atoms in HCHO molecules, respectively.…”

Ultrafast and Parts-per-Billion-Level MEMS Gas Sensors by Hetero-Interface Engineering of 2D/2D Cu-TCPP@ZnIn2S4 with Enriched Surface Sulfur Vacancies

“…The applications of resonant cantilever beams primarily focus on gas adsorption, gas sensing, and the determination of the thermodynamic and kinetic parameters of materials. Gas-sensitive materials such as graphene, metal–organic frameworks (MOF), metal oxides, and metal sulfides are employed in resonant cantilever beam MEMS gas sensors for the detection of NH 3 , toluene, NO 2 , and formaldehyde, and the interaction between gas molecules and sensitive materials has been investigated through the establishment of a surface interface model. − Up to now, resonant microcantilever sensors based on TEA-sensing materials with high sensitivity, a fast response, and a low limit of detection are urgently required to be developed.…”