A Copper Phosphosulfide-Based Highly Sensitive Ammonia Gas Sensor at Room Temperature

The present study explores the potential of copper phosphosulfide (Cu3PS4) as a highly sensitive and selective sensor element for detecting ammonia (NH3) gas. The nanosheets of Cu3PS4 obtained after exfoliation are assembled as a thin film for gas sensing studies. The results show that the sensor exhibits remarkable sensitivity, with a value of ~150% <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\pm ~4.3$ </tex-math></inline-formula>% at 10 ppm and a low detection limit of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$17.07~\pm ~0.51$ </tex-math></inline-formula> ppb of NH3. Furthermore, the sensor displays a high selectivity toward NH3, in the presence of O2, H2, C2H2, CO, CO2, SO2, H2S, and NO2 gases along with high reversibility. In addition, fast response and recovery times of ~90 and ~300 s for adsorption and desorption processes, respectively, are obtained. This is an essential feature to develop practical gas sensors. Raman spectroscopy reveals the mechanism of sensing to be based on charge transfer between the substrate and analyte. The effect of temperature on the sensing properties of the Cu3PS4 sensor is studied as well, providing insights into its stability and suitability for its use at different temperatures. Overall, the study demonstrates that Cu3PS4 is a highly sensitive and selective gas sensing material, particularly for NH3 detection, and suggests its potential use in various applications, including environmental monitoring and industrial processes.