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<p>This study reports the gas-sensing performance of titanium dioxide (TiO₂) and cadmium sulfide-doped titanium dioxide (CdS-TiO₂) thick-film sensors fabricated on alumina substrates. Sensing layers of TiO₂ (S<sub>1</sub>) and 2 wt% CdS-TiO₂ (S<sub>2</sub>) were prepared using laboratory-synthesized pastes and evaluated as chemiresistive sensors at room temperature (300&#xa0;K). The sensing behavior was investigated for various hydrocarbon gases, including LPG, methanol, ethanol, toluene, and benzene, over a concentration range of 0–5000&#xa0;ppm in air. The effect of relative humidity (10–90% RH) on sensor performance was also examined to assess environmental stability. The CdS-TiO₂ sensor exhibits a significantly enhanced response toward benzene, showing approximately 2.25 times higher sensitivity and more selectivity compared to the TiO₂ sensor under low-humidity conditions. In addition, CdS modification markedly improves the response and recovery characteristics. The TiO₂ film shows response and recovery times of 65&#xa0;s and 180&#xa0;s, respectively, whereas the CdS-TiO₂ sensor demonstrates reduced times of 15&#xa0;s and 103&#xa0;s when exposed to 5000&#xa0;ppm benzene at 300&#xa0;K. Humidity studies reveal a gradual decline in sensor response with increasing RH, with pronounced degradation observed at higher humidity levels, attributed to competitive adsorption of water molecules. The sensing mechanism is explained using the Frenkel-Poole electronic emission model. These results demonstrate that low-level CdS doping significantly enhances the sensitivity of TiO₂ toward benzene at room temperature, particularly under low-humidity conditions.</p>

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Effect of relative humidity on hydrocarbons sensing properties of TiO2-based gas sensors

  • 期刊论文

  • 发表日期：

    2026年6月3日

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  • Ankit Kumar Vishwakarma,
  • Ajaya Kumar Sharma,
  • Nutan Sharma,
  • Arjun Kumawat,
  • Lallan Yadava

摘要

This study reports the gas-sensing performance of titanium dioxide (TiO₂) and cadmium sulfide-doped titanium dioxide (CdS-TiO₂) thick-film sensors fabricated on alumina substrates. Sensing layers of TiO₂ (S1) and 2 wt% CdS-TiO₂ (S2) were prepared using laboratory-synthesized pastes and evaluated as chemiresistive sensors at room temperature (300 K). The sensing behavior was investigated for various hydrocarbon gases, including LPG, methanol, ethanol, toluene, and benzene, over a concentration range of 0–5000 ppm in air. The effect of relative humidity (10–90% RH) on sensor performance was also examined to assess environmental stability. The CdS-TiO₂ sensor exhibits a significantly enhanced response toward benzene, showing approximately 2.25 times higher sensitivity and more selectivity compared to the TiO₂ sensor under low-humidity conditions. In addition, CdS modification markedly improves the response and recovery characteristics. The TiO₂ film shows response and recovery times of 65 s and 180 s, respectively, whereas the CdS-TiO₂ sensor demonstrates reduced times of 15 s and 103 s when exposed to 5000 ppm benzene at 300 K. Humidity studies reveal a gradual decline in sensor response with increasing RH, with pronounced degradation observed at higher humidity levels, attributed to competitive adsorption of water molecules. The sensing mechanism is explained using the Frenkel-Poole electronic emission model. These results demonstrate that low-level CdS doping significantly enhances the sensitivity of TiO₂ toward benzene at room temperature, particularly under low-humidity conditions.