Conductometric H 2 S Sensors Based on TiO 2 Nanoparticles.

High-performance hydrogen sulfide (H 2 S) sensors are mandatory for many industrial applications. However, the development of H 2 S sensors still remains a challenge for researchers. In this work, we report the study of a TiO 2 -based conductometric sensor for H 2 S monitoring at low concentrations. TiO 2 samples were first synthesized using the sol-gel route, annealed at different temperatures (400 and 600 °C), and thoroughly characterized to evaluate their morphological and microstructural properties. Scanning electronic microscopy, Raman scattering, X-ray diffraction, and FTIR spectroscopy have demonstrated the formation of clusters of pure anatase in the TiO 2 phase. Increasing the calcination temperature to 600 °C enhanced TiO 2 crystallinity and particle size (from 11 nm to 51 nm), accompanied by the transition to the rutile phase and a slight decrease in band gap (3.31 eV for 400 °C to 3.26 eV for 600 °C). Sensing tests demonstrate that TiO 2 annealed at 400 °C displays good performances (sensor response Ra/Rg of ~3.3 at 2.5 ppm and fast response/recovery of 8 and 23 s, respectively) for the detection of H 2 S at low concentrations in air.