A group of researchers from Tomsk Polytechnic University in Russia have developed a new sensor that can be used to remotely detect hydrogen leaks.
While hydrogen is considered a promising alternative energy source, its application is complicated due to its highly explosive nature when mixed with oxygen. Dangerous situations may arise, for example, in case of hydrogen leaks from storage tanks.
"Therefore, it is necessary to detect hydrogen molecules in a gas mixture,” explained Pavel Postnikov, associate professor of the TPU Research School of Chemistry & Applied Biomedical Sciences. “Currently, there are various methods, including electronic sensors, although they are a potential source of spark. In this respect, we turned our attention to optical fibre.
“This is a simple and commercially available material. In addition, a sensor can be operated remotely, since optical fibre provides rapid and easy information transfer over long distances. The sensor can be installed in the engine of a hydrogen-powered machine or refuelling station.”
Optical fibre is a thin filament of optically transparent material, such as glass or plastic, able to transmit digital information in the form of a light pulse. The researchers modified fibres by removing a fragment of the fibre sheath and applying a fine layer of gold in its place through magnetron sputtering.
On the surface of this golden area, the effect of surface plasmon resonance takes place, which is the source of the analytical signal. The researchers used this golden area from a matrix solution as a basis for a metal-organic framework consisting of zinc molecules and particular organic compounds.
"This frame is extremely sensitive to hydrogen, since it captures its molecules from the air,” Postnikov continued. “Moreover, it is inert to other gases. Such sensors are comparable to a stationary chromatograph that is ten times more expensive and requires qualified personnel.
“For now, we have managed to achieve sensitivity and detection limit below 2%. In other words, our sensor can detect hydrogen in the air at a concentration below 2%, while the lower explosive threshold of a mixture of hydrogen and oxygen is about 4%.”
The key benefits of the new sensor are its simplicity, sensitivity, as well as an option for quick remote diagnostics.
"Another important feature is the sensor resistance to oxidising gases, for instance, carbon dioxide, and various oxides,” he added. “It is a problem for the modern sensors since these gases interfere with the sorption of hydrogen. Our sensor can easily work in the open air full of such gases.”
Results of the research have been published in the journal ACS Sensors.
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