Dip-coating decoration of AgO nanoparticles on SnO nanowires for high-performance HS gas sensors.

SnO nanowires (NWs) are used in gas sensors, but their response to highly toxic gas HS is low. Thus, their performance toward the effective detection of low-level HS in air should be improved for environmental-pollution control and monitoring. Herein, AgO nanoparticle decorated SnO NWs were prepared by a simple on-chip growth and subsequent dip-coating method. The amount of decorated AgO nanoparticles on the surface of SnO NWs was modified by changing the concentration of AgNO solution and/or dipping times. Gas-sensing measurements were conducted at various working temperatures (200-400 °C) toward different HS concentrations ranging within 0.1-1 ppm. The selectivity of AgO-decorated SnO NW sensors for ammonia and hydrogen gases was tested. Results confirmed that the AgO-decorated SnO NW sensors had excellent response, selectivity, and reproducibility. The gas-sensing mechanism was interpreted under the light of energy-band bending by sulfurization, which converted the p-n junction into n-n, thereby significantly enhancing the sensing performance.