Electrochemical power generation humidity sensor based on WS2 nanoflakes

The electrochemical power generation humidity sensor has received widespread attention due to its zero-power consumption. In this work, we propose an electrochemical power generation humidity sensor using WS2 nanoflakes as the humidity sensing material, without adding additional alkali metal salts (such as LiCl and NaCl) or other added materials or functional group treatments. The results show that the humidity sensor exhibits wide humidity detection range (18.7%−91.5% relative humidity (RH)), fast response/recovery speeds (8.4/5.2 s), good repeatability (20 cycles) and small humidity hysteresis (∼3.4% RH) at room temperature of 25°C. The output voltage of the humidity sensor is 0.47 V at 91.5% RH. Combined with good water molecule adsorption and proton conductivity of the WS2 nanoflakes, the humidity sensing and power generation mechanism of the WS2 electrochemical power generation humidity sensor can be explained by the redox reactions occurring at the positive and negative electrodes (Cu and Al). Finally, we demonstrate the application of the humidity sensor in respiratory detection. This work provides a useful approach for fabricating electrochemical power generation humidity sensor with a simple single humidity sensing material.