Highly sensitive NO2 detection on ppb level by devices based on Pd-loaded In2O3 hierarchical microstructures

- Pd-loaded In2O3 hierarchical microstructures with different Pd contents were synthesized by hydrothermal method.
- Pd content in In2O3 microstructures and best working temperature for NO2 detection were optimized.
- NO2 detection was achieved on ppb level for sensor attached with 1 mol% Pd-loaded In2O3.
- NO2 sensor based on 1 mol% Pd-loaded In2O3 shown great sensitivity and selectivity at lower operating temperature of 110 °C.

The special flower-like Pd-loaded indium oxide (In2O3) hierarchical microstructures with different Pd contents were successfully synthesized by a hydrothermal method, showing the features dimension of 5-7 μm diameter and 30 nm thick nanosheets. Developed NO2 sensors based on 1 mol% Pd-loaded In2O3 hierarchical microstructures demonstrated excellent NO2 detection at the ppb levels at lower operating temperature of 110 °C. These sensors also exhibited high response, fast response (180 s) and recovery (90 s) time and great reliability as well as simplicity in fabrication. Furthermore, selective detection of NO2 can be readily achieved with sensors attached with 1 mol% Pd-loaded In2O3 even with other common chemicals such as ethanol, CO, CH4 and H2 around. The electron depletion theory was used to explain the enhanced gas sensing mechanism.

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