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Scientists design Silicon-based Nano-cauliflowers to detect Hydrogen

Photo: Siddharth Kankaria / Research Matters

A group of scientists from the Indian Institute of Technology, Roorkee, has designed a highly efficient sensor using nanotechnology to detect hydrogen gas leakage. This invention could help address the problem of leakage of hydrogen, a major impediment in using hydrogen as a fuel for large-scale applications. “Growing demand for energy and the lack of fossil fuel sources have led to extensive research in the field of hydrogen as a future renewable energy resource, which can also be converted into electricity by fuel cells. But, hydrogen forms an explosive mixture with air once its concentration exceeds beyond the explosion limit (4%)”, says Prof. Ramesh Chandra from the Institute Instrumentation Centre and Centre for Excellence in Nanotechnology.

Hydrogen, when used as a fuel, is a ‘green’ fuel since it does not produce harmful gases as secondary products. The only residue it produces when burnt is water! So what limits its use as a fuel? “Hydrogen has a high propensity to leak and a high diffusion rate. Hence, safety is an important issue while considering hydrogen as a fuel for the future. As hydrogen can't be detected by human senses, a highly sensitive and selective sensor is today's necessity,” explains Prof. Chandra.

The researchers have designed the new sensor using cauliflower like nanostructures of Silicon carbide, an extremely strong compound of carbon and silicon. It can work at relatively higher temperatures of about 300oC for a long time than most available sensors. This makes their use possible in aeronautical and combustion engines. They developed the sensor by depositing Palladium decorated Silicon carbide (SiC) nano-cauliflowers directly on a silver (Ag) coated film of porous anodic alumina (AAO), a honeycomb like nanostructure formed by aluminium oxide.

Laboratory observations have shown that the new sensor is electrically stable, has high sensitivity and selectivity to hydrogen and is insensitive to changes in humidity. It can detect hydrogen present in extremely small quantities (2–500 part per million). The sensitivity and selectivity exhibited by the sensor towards hydrogen is mostly due to the layered arrangement of SiC cauliflowers structure. This unique structure facilitates more diffusion of hydrogen molecules and better interaction with the detection material. The chemically inert nature and the structure of AAO restrict the transport of molecules towards and within the AAO-SiC film, and also add to the efficiency of the sensor.

“By working with thin films, we are able to tailor the composition, geometry, and structure of the material. This capability gives the opportunity to tune the microstructure and the chemical composition to develop suitable materials for gas sensing applications. The fast response-recovery and low temperature operation with a long-term stability are prime areas of improvement for future hydrogen sensors”, says Prof. Chandra. This study with a simple, robust, and cost-effective method for detecting hydrogen, is definitely a small step towards realizing the future of a hydrogen-powered world.