Hydrogenation effect on 2D ZnO single crystal/ZnO–SnO2 two phase ceramics and its enhanced mechanism in H2 gas sensing

In this work, a 1D/2D two-phase structure of ZnO single-crystal nanosheets/ZnO–SnO2 nanorods was constructed, and the hydrogen gas sensing properties including selectivity have been enhanced by this low-cost way without noble metal doping. It was proved that hydrogenation effect on ZnO (0001) single crystal facets was the key to forming the low resistance surface in hydrogen gas, leading significantly enhancement in response and selectivity. The response (Ra/Rg) to 200 ppm hydrogen gas exceeded 400 at a low operating temperature of 150 °C, response/recovery time in 100 ppm H2 was only 30 s/8 s. The sensor also has good selectivity for hydrogen detection. The enhancement in gas sensing properties due to dual mechanism of the hydrogenated low-resistance surface and the resistance modulation of ZnO/SnO2 heterojunctions, which proposed in this paper.