Dual-temperature H₂ sensing with a wide dynamic range enabled by PdO/Pd-ZnO nanorod arrays

Area of Science:

• Materials Science
• Chemical Engineering
• Sensor Technology

Background:

• Conventional metal-oxide sensors struggle with reliable hydrogen (H₂) detection across trace-to-percent concentration ranges.
• Accurate H₂ monitoring is critical for safety, from early leak detection to catastrophic release scenarios.

Purpose of the Study:

• To develop a single chemiresistive sensor capable of operating across the entire H₂ concentration spectrum.
• To elucidate the sensing mechanism using advanced spectroscopic techniques.

Main Methods:

• Fabrication of PdO/Pd-decorated, metal-organic framework (MOF)-derived ZnO nanorod arrays.
• Utilizing a temperature-gated sensing strategy with two distinct operating regimes.
• Employing operando near-ambient pressure X-ray photoelectron spectroscopy (NAP-XPS) for mechanism elucidation.

Main Results:

• A single device achieved trace H₂ detection (49 ppb limit) at 125°C and ultrahigh response (3632 to 1% H₂) up to 2.5% at 250°C.
• Demonstrated a continuous detection window spanning approximately 5 orders of magnitude.
• Unraveled the sensing mechanism involving oxygen-mediated pathways and PdHₓ-assisted spillover.

Conclusions:

• The developed hierarchical ZnO nanostructure offers a versatile platform for broad-range H₂ sensing.
• This technology bridges the gap for full-scenario H₂ safety monitoring, from early warning to major release.
• The temperature-gated approach provides a robust solution for challenging H₂ detection applications.