Preparation and enhanced acetone sensing properties of flower-like α-Fe2O3/multi-walled carbon nanotube nanocomposites

Hybridizing hierarchically structured alpha-Fe2O3 with multi-walled carbon nanotube (MWCNTs) is highly desirable for improving the performance of alpha-Fe2O3 based gas sensors. In this work, we developed a simple solvothermal method combined with heat treatment for the preparation of flower-like alpha-Fe2O3/MWCNTs nanocomposites with a flexible three-dimensional nanostructure. The characterization results showed that 4-8 mu m alpha-Fe2O3 flower-like structures, formed by alpha-Fe2O3 nanosheets, were attached to the MWCNTs surface. Gas sensors based on the alpha-Fe2O3/MWCNTs nanocomposites exhibited a greater response, better selectivity, lower operating temperature, and good recovery towards acetone compared with pure alpha-Fe2O3. The response of the composites towards 50 ppm of acetone reached 20.32 at 220 degrees C, which was 3.49 times that of the pure alpha-Fe2O3 at its optimal operating temperature (260 degrees C). The response time of the composites towards 50 ppm acetone was 2.3 s, which was quicker than that of the pure alpha-Fe2O3. Overall, the gas-sensing performance of the alpha-Fe2O3/MWCNTs nanocomposites was enhanced. This can be assigned to the increased surface area with more active sites, improved gas transmission due to the open-frame structure, and better electrical transmission capacity due to the bridging role of the MWCNTs and the intimate alpha-Fe2O3-MWCNTs heterojunction.