A hydrogen fuel cell is a combination of hydrogen and oxygen.chemical energyA power generating device that converts directly into electrical energy. The basic principle iselectrolyzed waterofreverse reactionThe hydrogen and oxygen are supplied to the anode and cathode respectively, and the hydrogen diffuses outward through the anode andElectrolyteAfter the reaction occurs, the emitted electrons reach the cathode through an external load.
 

 
Hydrogen fuel cell has the characteristics of no pollution, low noise and high efficiency. It can be said to be a very ideal energy utilization device. If the source of hydrogen is made by using renewable energy (such as solar energy, wind energy, water energy) to decompose water, then the whole process can be said to be the cleanest, and it can be said that hydrogen fuel The cell is a clean energy with "zero emission"The use of hydrogen is important for sustainable development and is permeating all aspects of our lives.

 
Despite the benefits of hydrogen fuel cells, there are still many problems to be solved. For example, the energy source hydrogen may leak during transportation, storage, and application.
The hydrogen atom (H) is the lightest atom in the world. Commonly referred to as hydrogen is a gaseous hydrogen molecule (H2) formed by the combination of two hydrogen atoms.

Because it is very small, it is easy to leak and spread, and colorless and tasteless, it is difficult to detect its leakage or not.The explosive concentration range is wide, the lower explosive limit is 4.0vol%, and the upper explosive limit is 75.6vol%. The explosive range is four times that of ordinary flammable gases (methane, propane, isobutane), so hydrogen is very dangerous.

 
Industrial sites generally require an alarm signal when the gas reaches a certain content in the air. The low report generally requires 5% LEL ~ 25% LEL. If there is a high report, it is set at 50% LEL. (It is stated in 4.3.1.8 in the GB15322.1-2019 that 100%LEL of hydrogen corresponds to 4% vol).
There is another standard for the hydrogen generator, which requires an alarm signal when the hydrogen content in the air reaches 0.4 vol, and a shutdown when the hydrogen content reaches 1.6 vol. (GB/T31138-2022 6.4.9 has instructions)

Therefore, the alarm requirement for H2 leakage must be at least 4000PPM before the alarm!!!

Here, I would like to introduce a Figaro brand sensor that is very suitable for hydrogen leak detection by Shenzhen Science and Technology Agency: TGS2616

 
Principle:

When the tin oxide particles are exposed to oxygen at a temperature of several hundred degrees, the oxygen captures the electrons in the particles and is adsorbed to the surface of the particles. As a result, an electron depletion layer is formed in the tin oxide particles. Since the tin oxide particles used in the gas sensor are generally very small, the entire particles will enter the state of the electron depletion layer in the air. This state is called volume depletion. On the contrary, a state in which the center part of the particle fails to reach the depletion layer is called domain failure (regional depletion). When the oxygen partial pressure rises from zero (flat band) in the order of small ([O-](I))→ medium ([O-](II))→ large ([O-](III)), the changes in the band structure and electron conduction distribution are shown in the following figure ([O-]: adsorbed oxygen concentration). In the capacity depletion (volume depletion) state, the thickness change of the electron depletion layer ends, resulting in the Fermi level conversion pkT, the electron depletion state advances to the pkT increases, and the pkT decreases.
 
TGS2616-C00 gas sensors for detecting hydrogen
The TGS2616-C01 contains a newly developed sensitive element, which is very little affected by interference gases such as alcohol, and has a high selectivity to hydrogen.
     

Features:
High selectivity to hydrogen
Small size, low power consumption
Simple application circuit