Porous SiO₂ Nanofibers Loaded with CuO Nanoparticles for the Dosimetric Detection of H₂S

Mesoporous SiO2 nanofibers were prepared by electrospinning dispersions of preformed SiO2 nanoparticles and infiltrated with soluble Cu compounds, forming CuO/SiO2 nanocomposites after heat treatment in ambient air. These composites were used as sensor material in H2S dosimeters, which is based on the formation of conductive CuS, allowing for the dosimetric detection of H2S via the significant increase in conductance. The use of CuO/SiO2 nanocomposites targeted the improvement of the morphological stability of CuO nanostructures during the H2S detection, being confined in a rigid nanoscopic scaffold. Also, we aimed at understanding the parameters determining the decrease in sensing performance commonly observed for CuO-based H2S sensors. As a main result, these CuO/SiO2 nanofibers can be used for gas sensing of H2S in a quasi-continuous and dosimetric detection mode for up to 130 cycles for a concentration of 5 ppm, which exceeds the performance of pure CuO materials. As a concentration of 5 ppm is regarded as a level above which H2S is considered to be harmful, the materials show potential for H2S sensors with long-term stability. The deterioration in the sensing properties is attributed to the irreversible formation of CuSO4. Building on these insights, our study indicates strategies to further improve CuO-based sensors for H2S.