Trace level detection of NH3 at room temperature using Cd-ZnFe2O4 thin films
Ravikumar Thangavel1, Kalainathan Sivaperuman1, Logu Thirumalaisamy2
1Centre for Nanotechnology Research, Vellore Institute of Technology, Vellore 632014, India.
Iscience
|January 7, 2026
Summary
This study developed economical, efficient ammonia (NH3) gas sensors using cadmium-doped zinc ferrite (Cd-doped ZnFe2O4) thin films. The best-performing sensor detects low NH3 concentrations at room temperature with high sensitivity and stability.
Area of Science:
- Materials Science
- Chemical Sensing
- Nanotechnology
Background:
- Ammonia (NH3) gas detection is crucial for industrial, environmental, and safety applications.
- Developing economical and efficient room-temperature NH3 sensors remains a challenge.
- Metal oxide semiconductors offer potential for gas sensing due to their tunable electronic properties.
Purpose of the Study:
- To develop economical and efficient ammonia (NH3) gas sensors operating at room temperature.
- To investigate the effect of Cadmium (Cd) doping on the sensing properties of ZnFe2O4 thin films for NH3 detection.
- To optimize the composition of Cd-doped ZnFe2O4 for enhanced gas sensing performance.
Main Methods:
- Thin films of Cd-doped ZnFe2O4 (Cd_xZn_1-xFe2O4) were synthesized using the spray pyrolysis technique.
- Gas sensing performance was evaluated by measuring the response to varying concentrations of NH3 at room temperature.
- Material characterization included analysis of morphology, composition, and structural properties.
Main Results:
- Cd-doped ZnFe2O4 thin films exhibited significantly enhanced NH3 sensing performance compared to undoped ZnFe2O4.
- The Cd0.5Zn0.5Fe2O4 (ZFCD5) film showed the highest response (approx. 8) at 1 ppm NH3.
- The ZFCD5 sensor demonstrated fast response (105 s) and recovery (54 s) times, high sensitivity (10.07 ppm^-1), repeatability, selectivity, and stability over 6 weeks.
- Improved sensing performance was attributed to increased active sites from angular-rod-like morphology and enhanced charge transfer.
- Cd incorporation boosted defect density and adsorption-desorption efficiency, leading to a 10-fold increase in response.
Conclusions:
- Cd-doped ZnFe2O4 thin films are promising materials for developing highly sensitive and efficient room-temperature NH3 sensors.
- The spray pyrolysis method is effective for fabricating these sensor materials.
- These sensors have potential applications in industrial monitoring, environmental protection, and safety systems.
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