Dip-coating decoration of Ag 2 O nanoparticles on SnO 2 nanowires for high-performance H 2 S gas sensors.

SnO 2 nanowires (NWs) are used in gas sensors, but their response to highly toxic gas H 2 S is low. Thus, their performance toward the effective detection of low-level H 2 S in air should be improved for environmental-pollution control and monitoring. Herein, Ag 2 O nanoparticle decorated SnO 2 NWs were prepared by a simple on-chip growth and subsequent dip-coating method. The amount of decorated Ag 2 O nanoparticles on the surface of SnO 2 NWs was modified by changing the concentration of AgNO 3 solution and/or dipping times. Gas-sensing measurements were conducted at various working temperatures (200-400 °C) toward different H 2 S concentrations ranging within 0.1-1 ppm. The selectivity of Ag 2 O-decorated SnO 2 NW sensors for ammonia and hydrogen gases was tested. Results confirmed that the Ag 2 O-decorated SnO 2 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.