Dutch researchers invent hydrogen sensors that can be used at room temperature

[ China Instrument Network Instrument Development ] Hydrogen is one of the potential alternative energy sources for replacing fossil fuels. However, it is highly flammable. Therefore, if hydrogen economy is to be developed, a sensor capable of detecting hydrogen is indispensable. However, the biggest challenge of hydrogen sensors so far is that higher temperatures are required to function, and the sensitivity is lower and the reaction time is slower.

Researchers from the Delft University of Technology (TU Delft) in the Netherlands claim that they have overcome the above challenges and developed a new type of sensor made of thin layers of tungsten trioxide (WO3). High resistance and the ability to sense hydrogen using a platinum catalyst can sense a hydrogen concentration of 1 pppm near room temperature, and a reaction time of less than 1 second when the hydrogen concentration exceeds 100 pppm.

One of the characteristics of tungsten trioxide is that the crystal lattice structure contains many open spaces, so that the material is easily doped, thereby introducing other atoms to change its electrical characteristics. Giordano Mattoni, lead author of TU Delft's technical paper, said that tungsten trioxide itself is an insulator, "but after doping, it can change the color of the material by adding a charge and gradually transform it into a metal; we try to mix hydrogen Mix with the tungsten trioxide film and see if it can be a sensor."

The results proved to be possible; the researchers first made a thin layer of tungsten trioxide by means of a pulsed laser deposition method, so that the material layer could be deposited separately on a single substrate; Mattoni pointed out: “Using this method, we made a thin layer of tungsten trioxide with a thickness of only 9 nm.”

The researchers then placed a platinum drop at the top of the thin layer of tungsten trioxide; platinum has a well-known property that acts as a catalyst for separating hydrogen molecules into individual hydrogen atoms, and the researchers observed that those atoms could Enter the crystal lattice of tungsten trioxide and slowly convert it from insulator to metal. Mattoni pointed out: "This means that by measuring the electrical resistance of the material, we can determine the concentration of hydrogen in the environment."

The researchers' experiments exposed the tungsten trioxide film to different environmental conditions, including normal air, a hydrogen-mixed environment, and a vacuum. The experimental results show that the resistance and sample color (optical image display) will be It changes when exposed to hydrogen, but returns to its original state in normal air.

The new hydrogen sensor developed by TU Delft is the biggest difference from other similar sensors in that it can be used at room temperature. “The sensitivity is higher than other products on the market and can be reused in a matter of minutes;” Mattoni also said: “In addition, by increasing or decreasing the temperature of the sensor, the sensitivity can be adjusted for different applications.” Because the film is compatible with current semiconductor technologies, the new hydrogen sensor has the potential to be mass-produced, and the research team is preparing to patent the technology.

(Original title: Researchers invent hydrogen sensors that can be used at room temperature)