Study Of H₂S Sensoring Performance Of Sn0₂/ZnO Heteronanostructures

With the development of technology and modern industry, various types of gases are increasingly released into the air, resulting in a serious environmental pollution. Waste gases could endanger not only environment but also human health and public safety. In recent years,with large-scale fog and haze weather appeared frequently the environmental protection and air quality monitoring have attracted more and more attention. Gas sensor can be used both in our daily life and in the work to monitor the concentration of harmful gases, and then remind people to avoid unexpected gas leakage. Among harmful gases, H2S is one kind of the colorless and very poisonous gas that often produces in many kinds of chemical working environment. It is very important to develop gas sensors which can detect trace H2S in the atmosphere because low concentration of H2S gas is badly harmful to human body. SnO2 and ZnO are two categories of metal oxide semiconductors usually used for gas sensors. They all have a good sensitivity to H2S gas, but the sensors made of SnO2 and ZnO still have some drawbacks in detection limit concentration of H2S and working temperature.Herein we develop a facile strategy to fabricate net-like SnO2/ZnO heteronanostructures using graphene sheets as hard templates by a wet-chemical method. Graphene/SnO2 (G/SnO2)composite was first synthesized. Then we synthesized Graphene/SnO2/ZnO (G/SnO2)composite by introducing ZnO to G/SnO2. After heating the sample at 500? for 2h, under the ambient atmosphere, net-like SnO2/ZnO heteronanostructures were synthesized. Net-like SnO2 and ZnO homonanostructures were synthesized by the same method. The samples were characterized by scanning electron microscope, transmission electron microscope, X-ray diffraction and nitrogen adsorption/desorption analysis. The characterization results show that SnO2/ZnO heteronanostructures has two-dimensional net-like porous feature and large surface areas. Sizes of the nanoparticles in the net-like heteronanostructures are greatly smaller than those in the net-like homonanostructures. Specially, heterojunctions formed at the interfaces between SnO2 and ZnO. Small size effect and the formation of heterojunctions at the interfaces are very beneficial to improving the sensitivity and gas selectivity of H2S and lowering operating temperatures.As a result, the net-like SnO2/ZnO heteronanostructures exhibited superior H2S sensing properties including higher sensor response, and better selectivity and long-term stability to net-like SnO2 and ZnO homonanostructures and other types of metal oxide-based nanocomposites. Importantly, the SnO2/ZnO heteronanostructures could detect 10 ppb H2S even at a working temperature of 100?. Therefore, the net-like SnO2/ZnO heteronanostructures have very promising applications in high-performance H2S sensors.