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Chemical warfare agents (CWAs) are chemical substances intended for use in military operations to kill, injure, or incapacitate an enemy. It is very important to detect toxic CWAs at trace levels on site. Compared with traditional CWA analysis instrument methods, chemiresistive gas sensors present advantages of being small, fast, and inexpensive. Chemiresistive gas sensors are still an important research topic with the development of nanofabrication technology and new kinds of sensing materials, including carbon nanotubes, graphene, and black phosphorus (BP). Chemiresistive gas sensors are divided into three categories according to the type of sensitive materials: carbon- and BP-based materials, conductive polymers, and metal oxide semiconductors. A brief analysis was carried out on fabrication strategies using sensitive materials, including hydrogen bonding strategies, nanostructures, morphology, doping effects, composite materials, and other material application methods, and the sensitive materials and detection effects are summarized in this study. This review aims to provide guidance in the development of chemiresistive sensors for the detection of CWAs. [ABSTRACT FROM AUTHOR]

Chemical warfare agents (CWAs) are extremely toxic chemicals, necessitating rapid, easy-to-use, sensitive and selective sensors for detection. Dimethyl methylphosphonate (DMMP) serves as a simulant of nerve agents and is commonly used to evaluate the efficacy of sensors in detecting these hazardous compounds. In this context, this paper proposes a one-dimensional (1D) photonic crystal (PC) gas sensor functionalised with UIO-66-COOH, leveraging a hydrogen-bonding-based acidic strategy, for rapid and sensitive DMMP detection. To optimise DMMP uptake, the organic ligand, UIO-66, is functionalised by grafting additional carboxyl groups to facilitate hydrogen-bonding interactions with the P O groups of organophosphorus gases such as DMMP. Subsequently, attenuated total reflection surface-enhanced infrared absorption spectroscopy is performed to quantitatively monitor the impact of strong interactions between the P C bonds and P O bonds of DMMP and the adsorption sites of metal–organic frameworks (MOFs) during adsorption. The results reveal an increase in the number of hydrogen-bonding sites available for DMMP adsorption, thus promoting hydrogen-bonding interactions. Furthermore, density functional theory calculations are employed to analyse the presence and strength of hydrogen bonds between the MOFs and DMMP. The results reveal that the chemisorption energy of UIO-66-COOH exceeds those of its variants, corroborating the findings of sensing experiments. Overall, the developed 1D PC gas sensor comprising UIO-66-COOH/TiO 2 demonstrates excellent stability and reproducibility, with a limit of detection of 0.3 ppm. This sensor also demonstrates enhanced selectivity towards organophosphorus gases compared to volatile organic compounds. • The first detection of DMMP using a UIO-66-COOH/TiO 2 photonic crystal sensor. • Hydrogen-Bonded Acid-Based Strategy to Enhancing the Selectivity of PC Sensors. • ATR-SEIRAS and DFT calculations demonstrate the presence of strong interactions. • The sensor has a fast response time (< 3 s) and high sensitivity (300 ppb). • Design of a chamber device for PC gas sensing to reduce gas diffusion time. [ABSTRACT FROM AUTHOR]