H₂ Detection Improved Hydrogen Sensor Loves Humidity

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While conventional hydrogen sensors are weak in humid environments, a new Swedish design is even more sensitive in high humidity. The secret: platinum nanoparticles use water vapor as an amplifier.

Hydrogen technology is booming in Germany: from Infineon's XENSIV TCI sensor to funded projects such as H₂-Control and HySABi, German industry is working intensively on reliable H₂ detectors. A key problem here is that existing sensors often fail in high humidity. This becomes critical when hydrogen is present. Researchers at Chalmers University of Technology in Sweden are now presenting a novel approach that elegantly solves this problem.

The Humidity Dilemma of Hydrogen Sensor Technology

Wherever hydrogen is present, safety sensors are indispensable. This starts with fuel cell vehicles and extends to filling stations and industrial storage facilities. The problem is that most current sensors become slower or less reliable in humid environments. At the same time, water vapor is inevitably produced during the H₂ reaction in fuel cells, and the membranes even require additional moisture to prevent them from drying out.

"The performance of hydrogen sensors varies drastically depending on the environment, and humidity is a critical factor," explains PhD student Athanasios Theodoridis from Chalmers University, lead author of the study published in ACS Sensors. "Many sensors become sluggish or less effective in humid environments. With our new sensor concept, we discovered the opposite: the higher the humidity, the stronger the hydrogen response."

Platinum Nanoparticles As A Dual-Function Element

The fingertip-sized sensor is based on a dual-function principle: platinum nanoparticles act simultaneously as a catalyst and sensor element. The platinum particles accelerate the chemical reaction between hydrogen and atmospheric oxygen, generating heat. This causes the moisture film on the sensor surface to "boil away".

The measuring principle in detail:

• H₂ concentration determines how much water film evaporates
• Humidity controls the film thickness
• Hydrogen content is determined via the film thickness measurement
• Higher humidity = thicker film = better sensor effectiveness

Detection takes place via plasmonic effects: The platinum nanoparticles absorb light and show characteristic color changes. The system triggers an alarm at critical H₂ concentrations.

A Sensitivity of 30 ppm in A Humid Environment

The measurement results are impressive: the sensor detects hydrogen down to 30 ppm (0.003 percent), especially in humid environments. This makes it one of the most sensitive H₂ sensors in the world for these application conditions.

Characteristic performance data:

• Detection threshold: 30 ppm H₂
• Long-term stability: >140 hours continuous operation
• Special feature: Performance increases with humidity
• Optical detection via plasmon resonance

"We tested the sensor continuously for 140 hours in humid air," says Theodoridis. "The tests showed stable performance at different humidity levels and reliable H₂ detection under real conditions."

From Palladium Absorber to Platinum Catalytic Converter

Professor Christoph Langhammer's research group has been developing plasmonic hydrogen sensors for years and has achieved several breakthroughs in terms of speed, sensitivity and AI-optimized response. Until now, the team has relied on palladium nanoparticles that absorb hydrogen like a sponge.

The new platinum concept, developed as part of the TechForH2 competence center, leads to a completely new type of sensor: the "catalytic plasmonic hydrogen sensor". Langhammer is also co-founder of the sensor company Insplorion and works there in an advisory capacity.

German H₂ Strategy Needs Robust Sensor Technology

The development hits the nerve of the German hydrogen strategy. Current BMWE/BMWK-funded projects such as H₂-Control (real-time quality control for filling stations), HySABi (miniaturized vehicle sensors) and EISBaEr (plant monitoring) address similar challenges.

"There is currently strong demand for sensors that work well in humid environments," emphasizes Langhammer. "As hydrogen plays an increasingly important role in society, there is a growing demand for sensors that are not only smaller and more flexible, but can also be produced on a large scale and at low cost. Our concept meets these requirements well."

Langhammer sees the future of hydrogen sensor technology in combinations of materials: "We expect to have to combine different active materials to create sensors that work well regardless of the environment. We know now: Certain materials provide speed and sensitivity, others resist moisture better." (heh)

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