Hydrogen Halide Gas Sensors: Active Materials, Operation Principles, and Emerging Technologies

ABSTRACT Hydrogen halide gases are one of the most wide‐spread pollutants of atmosphere, which are generated by various industrial sectors or natural processes, and may dramatically affect human health above certain thresholds of exposure. Hence, it is critically important to develop effective sensing methods for these gases. Herein, we review the recent progress as well as fundamental mechanisms, materials, and designs for the hydrogen halide gas sensors. We discuss in detail four major types of sensors: acoustic, chemical, optical, and the emerging nanophotonic sensors, categorizing them based on their operation principles. Acoustic sensors are discussed with a focus on microbalance‐based and surface acoustic wave gas sensors. Chemical sensors are considered from the point of view of electrochemical and chemiresistive sensing mechanisms. Optical sensors are analyzed, covering fluorescence‐based optical sensors, laser absorption‐based techniques, photoacoustic spectroscopy, and nonlinear optical methods. Finally, emerging nanophotonic sensors are introduced, emphasizing plasmonic and all‐dielectric nanophotonic approaches. We offer insights into the key operation mechanisms of different types of sensors for hydrogen halide gases and provide their direct comparison.