Rapid Detection of Ultralow H₂S Concentration with on-chip Fabrication of SnO₂-based Gas Sensors by Direct Electrodeposition from Non-Aqueous Solvents

Hydrogen sulfide (H 2 S) causes significant impacts on human health and the environment due to its highly toxic properties. Thus, the design and development of gas sensors to detect and monitor H 2 S (especially at extremely low concentrations) are challenging tasks for scientists. In this work, SnO 2 gas sensors were successfully synthesized directly on a chip by Sn electrodeposition from ethylene glycol solutions + a post-treatment (calcination) stage (to form and stabilize SnO 2 ). Mechanisms and kinetics of Sn electrodeposition on Pt microelectrodes were thoroughly studied using electrochemical techniques. These fabricated gas sensors exhibit a high selectivity toward H 2 S gas and an effective response to low-level concentrations of H 2 S in the range of 0.1 ppm–1 ppm at different working temperatures. The influence of electrodeposition conditions and calcination temperatures on the gas response of sensors were also examined. The results have verified that the electrodeposition method from ethylene glycol solutions is promising for the fabrication of ultrasensitive on-chip gas sensors.