Enhanced methane sensing properties of porous NiO nanaosheets by decorating with SnO2

Abstract

Two dimensional (2D) nanomaterials with porous structure have stimulated much research interest owing to their unique structure and fascinating physical and chemical properties. Here, ultrathin 2D porous nanosheets (PNSs) of pure and SnO2-decorated NiO with uniform hexagonal shape were synthesized by using the pre-synthesized Ni(OH)2 nanosheets precursor. The obtained SnO2/NiO PNSs were about 100∼150 nm in size and their mean thickness was about 7.5 nm. The gas sensing properties of the prepared pure and SnO2-decorated NiO PNSs were investigated intensively. It was found that after decorating with different amount of SnO2, the sensor based on NiO PNSs showed an improved sensing properties to methane (CH4), and the optimal SnO2 content in the composite was determined to be 2 mol%. At the optimum working temperature of 330 °C, the SnO2/NiO-2 sensor showed higher response and faster response/recover speed towards 500 ppm CH4 than the pure NiO sensor. In addition, the SnO2/NiO-2 sensor also exhibited a good long-term stability within 28 days, demonstrating its potential application for CH4 detection. The porous structure and p-n junction related sensing mechanism of SnO2/NiO PNSs was also discussed.