Low-Temperature Highly Robust Hydrogen Sensor Using Pristine ZnO Nanorods with Enhanced Response and Selectivity

Area of Science:

• Materials Science
• Nanotechnology
• Chemical Sensing

Background:

• Development of cost-effective and efficient gas sensors is crucial for environmental monitoring and safety.
• Zinc oxide nanorods (ZnO NRs) offer promising properties for gas sensing applications due to their large surface area and tunable characteristics.

Purpose of the Study:

• To investigate the hydrogen-sensing performance of solution-derived ZnO NRs on glass substrates.
• To optimize the sensing parameters (temperature, concentration) for enhanced hydrogen detection.
• To evaluate the selectivity, humidity influence, and long-term stability of the developed sensor.

Main Methods:

• Hydrothermal growth of vertically aligned ZnO NRs on ZnO seed-layer-glass substrates.
• Fabrication of interdigitated electrodes (IDEs) using aluminum.
• Gas-sensing measurements at various temperatures and gas concentrations (H2, NO2, CO, H2S, NH3).
• Impedance spectroscopy and humidity influence tests.

Main Results:

• Optimal hydrogen-sensing response of ~21.46% at 150 ppm H2 and 150 °C.
• High selectivity towards hydrogen over other tested gases (NO2, CO, H2S, NH3).
• Minimal influence of humidity on the hydrogen-sensing response (~20.5 ± 1.5% across 10-65% RH).
• Excellent long-term stability, with no significant response degradation after 10 months.

Conclusions:

• Solution-derived ZnO NRs are a viable low-cost material for sensitive and selective hydrogen gas sensors.
• The sensor exhibits robust performance, minimal humidity interference, and remarkable long-term stability.
• The observed sensing properties are attributed to the nanostructure, surface area, and intrinsic defects (oxygen vacancies) of ZnO NRs.