Humidity sensor based on ZnS/SnO2 nanocomposites with improved sensing properties

This work prepared ZnS, SnO 2 , and zinc oxide/tin dioxide (ZnS/SnO 2 ) composite materials by the hydrothermal method, and systematically studied their physicochemical properties. Humidity sensors were constructed based on these materials, and their humidity-sensing performances were tested. The characterization results show that ZnS has a cubic sphalerite structure, SnO 2 has an orthorhombic rutile structure, and the surface of ZnS/SnO 2 composites is rich in hydrophilic functional groups such as hydroxyl groups (-OH) and high-density oxygen vacancy defects. The results of the humidity-sensitive performance study showed that the ZnS/SnO 2 composites prepared under specific conditions exhibited good humidity-sensitive properties. These conditions include a molar ratio of ZnS to SnO 2 of 1:15, a reaction time of 12 h, and a reaction temperature of 200°C. The ZnS/SnO 2 humidity sensor, designed according to these optimized parameters, exhibits excellent performance at room temperature. It has an extremely high response of 2.14 × 10 6  %, a minimum hysteresis of 2.4 %, excellent linearity, and fast response and recovery times of 9.7 s and 38.6 s, respectively, over a humidity range of 11 % RH to 95 % RH. The successful fabrication of the ZnS/SnO 2 humidity sensor not only demonstrates its superior performance but also provides valuable insights into the design of high-performance sensors.