Constructing porous ZnO/SnO2 nanocomposites for the detection of methane at low operating temperature

Aimed at detecting methane (CH4) gas at low operating temperature, porous ZnO/SnO2 nanocomposites were constructed through a simple two-step method. Pure SnO2 with a diameter of approximately 120 nm was first synthesized via a hydrothermal method, and then a smaller and looser ZnO/SnO2 composite structure was obtained by introducing the second component ZnO. The CH4 sensing test results showed that the ZnO/SnO2 composites exhibited lower optimum operating temperature (OOT) than that of pure SnO2. Besides, compared with pure SnO2, the ZnO/SnO2 composite based sensor present higher response to CH4, as well as good repeatability, stability and linearity in a certain range of gas concentration. The improved sensitivity can be mainly attributed to the synergistic effect of porous structure and heterojunction formed between ZnO and SnO2.