Hydrogen sensors have been widely used in multiple fields [
17,
22]. For example, in the energy sector, the safe operation of hydrogen fuel cells and hydrogen refueling stations relies on the support of hydrogen sensors. In industrial production, hydrogen sensors are used to monitor potential hydrogen leaks during the production process, ensuring production safety. In environmental monitoring, hydrogen sensors can measure the concentration of hydrogen in the atmosphere to assess environmental pollution. Furthermore, hydrogen sensors also play an important role in aerospace and military fields. With continuous advancements in science and technology, new materials such as graphene and metal–organic frameworks (MOFs) have been widely applied in the development of sensitive materials for hydrogen sensing, which improves the sensitivity, selectivity, and stability [
23,
24]. Moreover, combined with the latest wireless communication technology and the internet of things (IoT) technology [
22], the developed wireless hydrogen sensing networks can achieve real-time monitoring of hydrogen concentration over large areas and multiple points, further improving the efficiency and accuracy of hydrogen leakage detection. Given the potential hazards associated with hydrogen leaks, key requirements have been established to ensure that these sensors operate effectively and safely. Typically, hydrogen sensors need to detect levels around 10 parts per million (ppm) to meet safety standards. Meanwhile, selectivity is another vital requirement to identify hydrogen without interference from other gases. Hydrogen-rich environments may contain gases like carbon monoxide, methane, and ammonia, which could interfere with gas identification. Moreover, the limit of detection (LoD) determines the lowest concentration of hydrogen that the sensor can accurately detect. Many applications require LoD capabilities as low as 0.1 ppm to comply with safety and environmental standards. Exposure to harsh environmental conditions or contaminants can degrade sensor performance, making stability a critical factor for consistent, reliable readings and for reducing the frequency of recalibrations or replacements. The milestone era of artificial intelligence of things (AIoT) in hydrogen sensing from nanohybrid structure toward optical and intelligent system can be found in Fig.
1. Hydrogen sensor development began in 1978 with research on hydrogen diffusion through platinum membranes at high temperatures and pressures, followed by the creation of a stable palladium-gate metal oxide semiconductor capacitor in 1981. In 1984, the Pd-MOS structure was applied to hydrogen sensing in catalytic reactions, and by 1988, metal–silicon dioxide–silicon structures were explored for hydrogen and ammonia detection. Entering the 21st century, wireless micro-cantilever chemical sensors based on micro-electrical and mechanical system (MEMS) technology were proposed in 1999–2000, alongside the development of a photoacoustic hydrogen sensor using laser amplitude modulation. Also in 2000, a hydrogen sensor based on optical fiber evanescent waves emerged, incorporating Pd-supported tungsten oxide as a sensitive material. Subsequent advances saw nanomaterials and novel structures gain prominence; for example, in 2007, a carbon nanotube–Pd catalyst interface was built via dielectrophoresis for hydrogen detection, and a surface acoustic wave hydrogen sensor using polyacetylene fiber was created, while titanium dioxide nanotube arrays were investigated for sensing. More recently, the focus shifted to self-powered and selective detection, with a triboelectric-based self-powered hydrogen sensor introduced in 2016 and a high-sensitivity thermoelectric silicon fabric sensor developed in 2021. Performance enhancements included fluorine plasma treatment for Pd/WO₃/SiC Schottky diode sensors in 2015, and artificial intelligence integration began, such as convolutional neural networks with random forests for sensor fault diagnosis in 2020, and a machine learning-enhanced SnO₂–TiO₂/MXene dual-gas sensor for hydrogen and ammonia detection proposed in 2025.