Low operating temperature and highly selective NH3 chemiresistive gas sensors based on Ag3PO4 semiconductor

Developing of novel chemiresistive gas sensing materials with desired unique gas chemisorption properties is of great important. In this work, motivated by the special electronic structure, Ag₃PO₄ semiconductor is systematically investigated as gas sensing material for the first time. Encouragingly, the Ag₃PO₄ nanoparticles based gas sensors exhibit high selectivity to NH₃ at near room temperature of 50 °C with negligible responses to the other gases (including H₂, CO, ethanol, acetone, NO₂ and SO₂). Furthermore, the responses decreased with the increase of operating temperature from 50 to 100 °C, indicating the superior NH₃ sensing activity. The in-situ infrared characterization and theoretical calculations reveal that the lone pair of NH₃ coordinate with the superficial silver atoms of Ag₃PO₄ accompanied with strong adsorption energy, efficient quantities electron migration and thermodynamic favorable, explained the origin of the high selectivity. Our work indicates that Ag₃PO₄ based materials are very promising low operating temperature and highly selective NH₃-sensing materials.