Hydrogen is a potential alternative energy source to fossil fuels; however, it is highly flammable, making sensors capable of detecting hydrogen essential for developing a hydrogen economy. To date, however, the biggest challenge for hydrogen sensors is that they require high temperatures to function, and they also suffer from low sensitivity and slow response times.
Researchers from Delft University of Technology (TU Delft) in the Netherlands have claimed to have overcome the aforementioned challenges and developed a novel sensor made from a thin layer of tungsten trioxide (WO3). This sensor combines high resistance with the ability to sense hydrogen using a platinum catalyst. It can sense hydrogen concentrations as low as 1 pppm at near room temperature, and the reaction time is less than one second when the hydrogen concentration exceeds 100 pppm.
Researchers first used a method called pulsed laser deposition to create thin layers of tungsten trioxide, allowing them to deposit layers of this material individually on a substrate. Using this method, they created tungsten trioxide layers only 9 nanometers thick.
The researchers then placed a droplet of platinum on top of a thin layer of tungsten trioxide; platinum has a well-known property of acting as a catalyst to separate hydrogen molecules into individual hydrogen atoms, and the researchers observed that those atoms could enter the lattice of tungsten trioxide and slowly transform it from an insulator into a metal.
The researchers exposed tungsten trioxide films to different environmental conditions, including normal air, an environment mixed with hydrogen, and a vacuum. The results showed that the resistance and sample color (as shown in optical images) changed when exposed to hydrogen, but returned to their initial state in normal air.
The biggest difference between the new hydrogen sensor developed by TU Delft and other similar sensors is that it can be used at room temperature. Because this thin film is compatible with current semiconductor technology, the new hydrogen sensor has the potential for mass production, and the research team is preparing to apply for a patent for this technology.
