☆ 4.8 Article

Highly Selective H2S Gas Sensor Based on Ti3C2TX MXene-Organic Composites

ACS APPLIED MATERIALS & INTERFACES (2023)

Journal

ACS APPLIED MATERIALS & INTERFACES

Volume 15, Issue 5, Pages 7063-7073

Publisher

AMER CHEMICAL SOC

DOI: 10.1021/acsami.2c19883

Keywords

MXene; H2S sensing; surface functional groups; density functional theory

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Abstract

Cost-effective and high-performance H2S sensors are in demand for human health and environmental monitoring. MXenes, specifically 2D transition-metal carbides and nitrides, have shown potential for gas sensing due to their good conductivity and abundant surface functional groups. This study reports a negative response of pristine Ti3C2Tx thin films for H2S sensing and further improvement of sensor performance using a composite of Ti3C2Tx flakes and conjugated polymers (PDS-Cl), achieving a thirtyfold sensing enhancement and a low limit of detection. The findings also contribute to a better understanding of the sensing mechanism and selectivity of MXene-based composites.

Cost-effective and high-performance H2S sensors are required for human health and environmental monitoring. 2D transition-metal carbides and nitrides (MXenes) are appealing candidates for gas sensing due to good conductivity and abundant surface functional groups but have been studied primarily for detecting NH3 and VOCs, with generally positive responses that are not highly selective to the target gases. Here, we report on a negative response of pristine Ti3C2Tx thin films for H2S gas sensing (in contrast to the other tested gases) and further optimization of the sensor performance using a composite of Ti3C2Tx flakes and conjugated polymers (poly[3,6-diamino-10-methylacridinium chloride-co-3,6-diaminoacridine-squaraine], PDS-Cl) with polar charged nitrogen. The composite, preserving the high selectivity of pristine Ti3C2Tx, exhibits an H2S sensing response of 2% at 5 ppm (a thirtyfold sensing enhancement) and a low limit of detection of 500 ppb. In addition, our density functional theory calculations indicate that the mixture of MXene surface functional groups needs to be taken into account to describe the sensing mechanism and the selectivity of the sensor in agreement with the experimental results. Thus, this report extends the application range of MXene-based composites to H2S sensors and deepens the understanding of their gas sensing mechanisms.

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Role of surface functional groups to superconductivity in Nb2C-MXene: Experiments and density functional theory calculations

Kai Wang, Haolin Jin, Hongye Li, Zhongquan Mao, Lingyun Tang, Dan Huang, Ji-Hai Liao, Jiang Zhang

Summary: The superconductivity of Nb2C-MXene with different functional groups, Cl and F, was investigated experimentally and theoretically. The results showed that Nb2C-MXene with Cl functional group exhibited superconductivity with a transition temperature of -5.2 K, while Nb2C-MXene with F functional group was not superconducting. These findings were consistent with both experimental and theoretical results. This study not only resolves the inconsistency in previous research but also provides reference for future investigations on the superconductivity of MXenes.

SURFACES AND INTERFACES (2022)