Observation on Switching Properties of WO₃-Based H₂ Sensor Regulated by Temperature and Gas Concentration

Area of Science:

• Materials Science
• Chemical Engineering
• Nanoscience

Background:

• Transition metal oxide semiconductors show promise for H2 sensors.
• Abnormal gas-sensing phenomena in these materials, particularly WO3, are increasingly researched.
• Understanding these anomalies is crucial for developing advanced gas sensors.

Purpose of the Study:

• To investigate the abnormal resistance changes in tungsten oxide (WO3) gas sensors at varying temperatures (80-200 °C and >200 °C).
• To propose a novel explanation for the observed gas-sensing anomalies.
• To elucidate the reaction mechanisms influencing sensor performance.

Main Methods:

• Hydrothermal synthesis of WO3.
• In situ Fourier-transform infrared spectroscopy (FT-IR) and in situ X-ray photoelectron spectroscopy (XPS).
• Density functional theory (DFT) calculations.

Main Results:

• WO3 exhibits abnormal resistance variations with different gases across temperature ranges.
• A synergistic effect involving surface valence alteration (W6+ reduction) and gas-surface adsorbed oxygen reactions explains the anomalies.
• The proposed mechanism accounts for temperature and gas concentration effects on sensor response.

Conclusions:

• A new, rational explanation for abnormal resistance changes in WO3 gas sensors is presented.
• The findings highlight the importance of synergistic effects in transition metal oxide gas sensing.
• This work provides a foundation for designing highly efficient WO3-based gas sensors.