Optical Sensor Based on Plasmonics Quickly Detects Hydrogen Gas

A new optical nanosensor could be used to quickly detect leaks when hydrogen mixes with air. Hydrogen, a clean and renewable energy carrier, is highly flammable when mixed with air. According to the research team from Chalmers University of Technology, the new sensor is the first to meet the future performance targets for use in hydrogen-powered vehicles.

The nanosensor is based on an optical phenomenon, a plasmon, which occurs when metal nanoparticles are illuminated and capture visible light. The sensor contains millions of metal nanoparticles of a palladium-gold alloy, a material that is known for its sponge-like ability to absorb large amounts of hydrogen. The plasmon effect causes the sensor to change color when the amount of hydrogen in the environment changes.

The researchers developed a plasmonic metal-polymer hybrid nanomaterial, where the polymer coating reduced the activation energy for hydrogen transport into and out of the plasmonic nanoparticles. In addition to providing protection, the plastic around the sensor increased the sensor’s response time by enabling hydrogen molecules to penetrate the metal particles faster. At the same time, the plastic acted as an effective barrier to the environment because it prevented any molecules other than hydrogen from reaching the nanoparticles.

Hydrogen sensors are needed both when the hydrogen is produced and when it is used — for example, in cars powered by a fuel cell. In order to avoid the formation of flammable gas when hydrogen is mixed with air, the sensors need to be able to detect leaks quickly. Courtesy of Yen Strandqvist/Chalmers University of Technology.

“We have not only developed the world’s fastest hydrogen sensor, but also a sensor that is stable over time and does not deactivate,” said researcher Ferry Nugroho. “Unlike today’s hydrogen sensors, our solution does not need to be recalibrated as often, as it is protected by the plastic.”

According to the researchers, the sensor is capable of detecting 0.1% hydrogen in the air in less than one second, making it efficient enough to meet the strict performance targets set by the automotive industry for application in hydrogen vehicles of the future.

Researchers from Chalmers University of Technology present the first hydrogen sensors ever to meet the future performance targets for use in hydrogen-powered vehicles. Courtesy of Mia Halleröd Palmgren/Chalmers University of Technology.

The work could lead to additional strategies for next-generation optical gas sensors with functionalities optimized by hybrid material engineering. Someday, the researchers hope that the sensor can be manufactured in series in an efficient manner — for example, using 3D printer technology.

“It feels great to be presenting a sensor that can hopefully be a part of a major breakthrough for hydrogen-powered vehicles,” said professor Christoph Langhammer. “The interest we see in the fuel cell industry is inspiring.”

The research was published in Nature Materials (https://doi.org/10.1038/s41563-019-0325-4).