Highly sensitive and selective H₂S gas sensor based on TiO₂ thin films

Hydrogen Sulfide (H2S) gas sensors with very high sensitivity, selectivity, and quick responses are highly demanding for practical industrial applications. However, achieving it remains a challenging due to high-cost fabrication, poor selectivity, and stability of existing sensor materials. In this work, we report the nanocrystalline TiO2 thin film based highly selective H2S sensor on a silicon substrate, which exhibits superior sensor response of similar to 112000% and similar to 85% at 50 ppm and 100 ppb concentration of H2S gas, respectively when operated at 100 degrees C. Also, it exhibits quick response time (similar to 48 s) and fast recovery time (5 min) with long term stability in H2S gas sensing. The sensitivity of H2S gas on the TiO2 film is related to its surface roughness and excessive chemisorbed oxygen on the surface of the film. Thus, it was found that TiO2 thin film with appropriate roughness and defects plays a significant role in achieving a much better H2S selectivity and sensitivity properties at lower ppm detection for the H2S gas sensor.