Au-Decorated WS2 Microflakes Based Sensors for Selective Ammonia Detection at Room Temperature

Gold nanoparticles decorated WS2 microflakes (Au/WS2) have been synthesized by an in situ chemical reducing process. A chemiresistive-type sensor using as-synthesized Au/WS2 heterostructures as sensing materials shows an improved response to different concentrations of ammonia compared to pure WS2 at room temperature. As the concentrations of gold nanoparticles increased in heterostructures, response/recovery speeds of the sensors became faster although the sensitivity of the sensor was compromised compared to the sensitivity of the sensor with lower concentrations of Au. In addition, the Au/WS2-based sensor indicated excellent selectivity to formaldehyde, ethanol, benzene and acetone at room temperature. The improved performance of the sensors was attributed to the synergistic effect of electronic sensitization and chemical sensitization between WS2 and Au.