Catalytic effect of silver nanoparticles on ZnO surface for CO gas-sensing applications

In the present work, the performance of ZnO and silver (Ag)-loaded ZnO nanoparticles-based chemical sensors were studied for 10 ppm CO at 150 degrees C operating temperature. In particular, Ag nanoparticles were decorated on ZnO surface by gas-phase synthesis method. Incorporation of Ag nanoparticles on ZnO surface led to enhancement in the surface resistance of active material due to higher work function of silver nanoparticles. At 150 degrees C, Ag nanoparticles effectively acted as catalyst which increased the rate of redox reaction between gas molecules and sensor surface. Ag-loaded ZnO sensor exhibited remarkable improvement in the sensing response (similar to 40%) as compared to pure ZnO (sensing response similar to 9%) for 10 ppm CO at 150 degrees C temperature. The CO gas-sensing performance together with the sensing mechanism of the Ag nanoparticles-decorated ZnO sensor under low detection limit (10 ppm) at low operating temperatures (50-150 degrees C) was discussed in detail. The current approach facilitates fabrication of cost-effective and highly selective gas sensor, which can detect even trace amount of CO at lower operating temperatures.