Enhanced CH4 sensitivity of porous nanosheets-assembled ZnO microflower by decoration with Zn2SnO4

In recent years, design and synthesis of heterostructured nanomaterials with high gas-sensing performance for detection of flammable and toxic gases has attracted much research interest. In this paper, pristine and Zn2SnO4-decorated ZnO microflowers with the size about 2-5 mu m and assembled by porous nanosheets of about 15 nm in thickness were successfully synthesized via a simple solvothermal method and subsequent calcination process. The methane (CH4) sensing properties of the prepared Zn2SnO4/ZnO were investigated and compared with that of the pure ZnO counterpart. It was found that after decorating with a small amount of Zn2SnO4, the ZnO sensor showed an improved gas sensing properties to CH4. At optimum operating temperature of 250 degrees C, the sensor based on SZ2 (Zn2SnO4/ZnO composite with the optimal Zn2SnO4 contend) showed a response as high as 27.2 to 1000 ppm CH4, which was about 3.2 times higher than that of SZ0 (pristine ZnO) sensor. Meanwhile, the SZ2 sensor also showed a fast response and recover characteristic, low detection limit (1.48 ppm), good repeatability and long-term stability. The Zn2SnO4/ZnO heterostructures related CH4 sensing mechanism was discussed.