Progress and prospects of research on hydrogen sensors

The development of hydrogen energy industry is of great significance to the construction of a clean, low-carbon, safe and efficient modern energy system, the realization of the "dual carbon" goal and the high-quality economic development. The safe use of hydrogen has always been a concern. Hydrogen sensors can quickly and accurately measure hydrogen concentration, and effectively prevent hydrogen leakage, explosion and other safety problems in the process of production, storage, transportation and use. In recent years, with the popularization and application of hydrogen energy and the rapid development of Internet of Things technology, the requirements for hydrogen sensors in security, remote monitoring and distributed measurement are increasing. In this paper, the principle, applicability and research status of different types of hydrogen sensors are reviewed and analyzed, and the development trend of hydrogen sensors is forecasted. Hydrogen sensors can be divided into catalytic, electrical, optical fiber, acoustic and other types according to sensing principles. The catalytic hydrogen sensor has simple structures, fast response and high sensitivity. However, the catalytic hydrogen sensor is greatly affected by the temperature and humidity, and it has poor gas selectivity and high working temperature, which leads to potential safety hazards. The electrical hydrogen sensor has simple structures, long service life, and is easy to be integrated and miniaturized. However, electrical signals are prone to environmental interference and lead to signal drift, and electrical sparks may be generated during the detection of electrical signals, which can cause explosions in the detection of combustible gas. Compared with traditional electrical sensors, fiber optic hydrogen sensors have higher security and anti-interference, and are convenient to realize distributed measurement and other excellent performance, which has become a research hotspot. The fiber optic hydrogen sensor is small in size, intrinsically safe, antielectromagnetic interference, and it can realize distributed spatial multi-point measurement. However, it is difficult to achieve commercial production due to its high cost, complex signal processing and expensive instruments for detection. The acoustic hydrogen sensor has high sensitivity and fast response time, but is greatly affected by temperature and humidity. The future challenges and opportunities for hydrogen sensors are also discussed in the last section. Under the background of Internet of Things and the era of big data, the research of hydrogen sensors will be gradually toward miniaturization, integration and distributed sensing. Moreover, it is necessary to realize hydrogen detection at high temperature and humidity. Future research in this field may focus on the following four aspects: (1) Reducing the cross sensitivity of temperature, humidity and other gases; (2) new hydrogen-sensitive materials such as nanomaterials and graphene; (3) performance optimization of hydrogen sensors at high temperature; (4) signal detection and demodulation device of fiber optic sensors.