Room Temperature Detection of H2S by Two Dimensional WS2 based Chemiresistive Sensors

Abstract

H2S is a toxic gas which play important roles in different applications. This work reports detection of H2S by tungsten disulphide (WS2) nanoflakes which was synthesized using a simple liquid exfoliation method. The thickness of the nanoflakes were found to range from 0.7–2 nm while the lateral dimensions varied between 2–4 µm when observed using atomic force microscopy. The band gap of WS2 nanoflakes was found to be 2.66 eV when studied using UV-Visible spectroscopy. The total flowrate of gas was found to modulate the sensing performance of WS2. Hence, the WS2 based resistive sensor was tested with 1–27 ppm of H2S at 100 sccm flowrate and with 0.7–5 ppm H2S at 1000 sccm flowrate at room temperature (23–25°C). WS2 nanoflakes exhibited 0.86–15.36% response for 1–27 ppm H2S at 100 sccm while the response was observed to increase and vary between 0.47–15.66% for 0.7–5 ppm at 1000 sccm. The recovery of the sensors at 1000 sccm was found to be incomplete but the sensor demonstrated excellent repeatability and selectivity towards H2S. The limit of detection of the sensor was found as 253 and 53 ppb at 100 and 1000 sccm, respectively.