High-response H2S sensor based on ZnO/SnO2 heterogeneous nanospheres

Abstract

Designing nanostructured materials to enhance gas-sensing performance is a key objective for sensor technology. In this paper, ZnO/SnO₂ heterogeneous nanospheres have been successfully synthesized through annealing as-synthesized SnO₂ nanospheres immersed in aqueous Zn(NO₃)₂ solution. Compared to the untreated pure SnO₂ nanospheres and commercial ZnO gas sensors, the ZnO/SnO₂ heterogeneous sensors showed exceptional electrical responses to H₂S gas at 300 °C. The response of the as-obtained ZnO/SnO₂ sensors towards 10 ppm H₂S can reach up to 99.6. Meanwhile, the sensors exhibited obvious sensitivity and fast response/recovery behavior towards trace H₂S gas, and achieved a detection limit of less than 1 ppm. Moreover, the gas test results revealed that the design of the ZnO/SnO₂ heterogeneous nanostructures enhanced the H₂S gas response and the selectivity in response to interfering gases such as NO, SO₂, CO, CH₄, and C₂H₅OH. The high sensitivity and dynamic repeatability observed in these sensors reveal that these heterogeneous nanostructures are promising as sensitive and reliable chemical sensors.