High Response and ppb-Level Detection toward Hydrogen Sensing by Palladium-Doped α-Fe₂O₃ Nanotubes

Area of Science:

• Materials Science
• Nanotechnology
• Chemical Engineering

Background:

• Developing sensitive and stable hydrogen sensors is critical for safety in industries like fuel cells and chemical manufacturing.
• Existing parts per billion-level hydrogen detection methods face challenges in meeting stringent industrial requirements.
• Iron oxide nanotubes offer a promising platform for gas sensing applications due to their unique nanostructure.

Purpose of the Study:

• To develop high-performance hydrogen sensors with parts per billion-level detection limits.
• To investigate the effect of palladium doping on the sensing properties of iron oxide nanotubes.
• To achieve enhanced response, selectivity, and stability for hydrogen detection.

Main Methods:

• Fabrication of palladium-doped iron oxide nanotubes (Pd@Fe2O3 NTs) using electrospinning with FeCl3·6H2O, PdCl2, and PVP, followed by air calcination.
• Characterization of the synthesized materials using Field Emission Scanning Electron Microscopy (FESEM), Transmission Electron Microscopy (TEM), and X-ray Diffraction (XRD).
• Evaluation of hydrogen sensing performance, including response, selectivity, repeatability, and limit of detection (LOD) at various concentrations and temperatures.

Main Results:

• Successful synthesis of iron oxide nanotubes with uniformly doped palladium nanoparticles, confirmed by characterization techniques.
• Palladium doping significantly enhanced the gas response of iron oxide nanotubes.
• 0.59 wt% Pd@Fe2O3 NTs exhibited a high response (Ra/Rg = 41,000) to 200 ppm hydrogen at 300 °C, with high selectivity and excellent repeatability.
• A significant response was observed even at a low detection limit of 50 ppb (Ra/Rg = 16.8).

Conclusions:

• Palladium-doped iron oxide nanotubes demonstrate excellent performance for hydrogen sensing, meeting critical safety requirements.
• The enhanced sensing performance is attributed to the high surface area of nanotubes, the formation of a PdO/Fe2O3 p-n heterojunction, and the catalytic activity of palladium nanoparticles.
• These findings pave the way for advanced hydrogen sensors in demanding industrial applications.