Imma Perfetto
Cosmos science journalist
Researchers have invented a highly sensitive, low-cost device which has been shown to outperform existing commercial hydrogen detectors.
Green hydrogen, which is made by electrolysing water using renewable energy, has great potential as a “clean” alternative to fossil fuels because it produces only water vapour and energy when combusted.
Hydrogen (H2) fuel can be used in gaseous or liquid form. But, as the Hindenburg disaster of 1937 tragically demonstrated, it is also dangerously explosive.
Humans can’t detect a hydrogen leak using their senses, so safety systems capable of reliably detecting leaks are a vital safeguard to prevent explosions or fires in the burgeoning hydrogen economy.
But according to Dr Suman Mandal of Saudi Arabia’s King Abdullah University of Science & Technology (KAUST), conventional hydrogen sensors face several limitations.
“These sensors often respond slowly to hydrogen leaks, cannot detect trace levels of hydrogen, and must be heated during operation,” he says.
Mandal and collaborators designed the new device to address these shortfalls. It is made from a semiconducting polymer, DPP-DTT, deposited onto a pair of platinum electrodes using a laboratory technique called spin-coating.
When the device is exposed to hydrogen, the current flowing through it is reduced by up to 10,000 times. This drop in current occurs in less than 1 second and corresponds to the concentration of hydrogen detected.
“This high responsivity ensures rapid and precise detection of gas leaks, which is essential for safety in industrial and transportation sectors,” says Mandal.
The device operates at room temperature and can detect traces of hydrogen at just 192 parts per billion while consuming barely 2 microwatts of power – equivalent to about that of a quartz or mechanical wristwatch.
Laboratory tests showed the device could operate over a wide temperature and humidity range and remained functional for 2 years.
The sensor could also detect hydrogen in mixtures of volatile molecules, such as ethanol and acetone, and in complex gas mixtures. It only failed when the atmosphere lacked oxygen, which is a critical component of how the device works.
Oxygen from the air enters the polymer and draws electrons from the material, increasing the current flowing through the device and leaving oxygen within the polymer and on the electrodes.
If hydrogen is also present in the air, it also passes through the polymer and reaches the electrodes. There it splits into hydrogen atoms that stick to the platinum’s surface.
Hydrogen and oxygen atoms then combine to form water, which escapes the device as water vapour. Removing oxygen reduces the current flowing through the device, which signals the presence of hydrogen.
“This is an entirely new hydrogen sensing mechanism,” Mandal says.
The team found that an inexpensive screen-printing method could be used to deposit DPP-DTT onto the electrodes while still producing a comparably responsive device. They say the sensor could be manufactured at low cost, making it an affordable and practical way to rapidly identify hydrogen leaks.
“I believe these efforts will help address hydrogen safety issues in a cost-effective and environmentally friendly manner,” says Mandal. The team has filed a patent on the work and plans to further develop the technology.
The research appears in a paper in the journal Nature Electronics.
