Highly selective detection of trace hydrogen against CO and CH4 by Ag/Ag2O-SnO2 composite microstructures

Both response and selectivity are key issues for a gas sensing material. Here, we presented a porous Ag/Ag2O-SnO2 composite with excellent sensing performance towards hydrogen. The optimal weight ratio of Ag to SnO2 was 3 wt% in the Ag/Ag2O-SnO2 composite, which gave the highest response of 40-200 ppm hydrogen at 170 °C. And what is more, it was nearly insensitive to carbon monoxide and methane at this temperature. The porous microspheres composite exhibited high response and rapid response (less than 5 s) to trace amount of hydrogen. The high response and excellent selectivity of this composite could be attributed to the high catalytic activity of Ag/Ag2O nanoparticles built on the surface of SnO2 microspheres, the Schottky barrier and low working temperature.