Highly Selective Ethanol Sensors Based on Co-Doped SnO₂ Nanoparticles Modified Bimetallic CoMn-Functionalized Metal Oxide Nanotetrapod Chemiresistors

Material modification techniques are pivotal for improving the material performance. In this study, the gas-sensing attributes of materials were enhanced through the modification of bimetallic Co@Mn-codoped ZnO nanotetrapods (ZnO(Co@Mn)) using transition metal Co-doped SnO 2 nanoparticles (SnO 2 (Co)). Gas-sensing tests showed that SnO 2 (Co)/ZnO(Co@Mn) nanocomposites exhibited superior performance, including high response, low operating temperature, high selectivity, and short response/recovery times. At the temperature of 280 °C, the gas sensor based on SnO 2 (Co)/ZnO(Co@Mn) nanocomposites demonstrates an impressive response intensity of 204.6 to 200 ppm of ethanol gas. This highlights the sensor’s ability to operate at a lower temperature while maintaining excellent stability. The response time and recovery time to 200 ppm ethanol gas were quantified as 18 and 20 s, respectively. Comparing with pure SnO 2 (Co) and ZnO(Co@Mn), respectively, the enhanced gas-sensing performances of the SnO 2 (Co)/ZnO(Co@ Mn) nanocomposites are mainly ascribed to the heterojunction generated from the hybrid of ZnO(Co@Mn) nanotetrapods with SnO 2 (Co) nanoparticles, which not only improved the response and selectivity to ethanol gas but also reduced the operating temperature.