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

•Flower-liked α-Fe2O3/MWCNTs nanocomposites were synthesized via a simple solvothermal method combined with heat treatment.•The α-Fe2O3 flower like the real flower bloom on MWCNTs.•The response of the flower-liked α-Fe2O3/MWCNTs nanocomposites towards 50 ppm acetone can touch 20.32 at 220 °C.•The improved gas sensing properties of nanocomposites can be attributed to higher surface and heterojunction structure. Hybridizing hierarchically structured α-Fe2O3 with multi-walled carbon nanotube (MWCNTs) is highly desirable for improving the performance of α-Fe2O3 based gas sensors. In this work, we developed a simple solvothermal method combined with heat treatment for the preparation of flower-like α-Fe2O3/MWCNTs nanocomposites with a flexible three-dimensional nanostructure. The characterization results showed that 4–8 μm α-Fe2O3 flower-like structures, formed by α-Fe2O3 nanosheets, were attached to the MWCNTs surface. Gas sensors based on the α-Fe2O3/MWCNTs nanocomposites exhibited a greater response, better selectivity, lower operating temperature, and good recovery towards acetone compared with pure α-Fe2O3. The response of the composites towards 50 ppm of acetone reached 20.32 at 220 °C, which was 3.49 times that of the pure α-Fe2O3 at its optimal operating temperature (260 °C). The response time of the composites towards 50 ppm acetone was 2.3 s, which was quicker than that of the pure α-Fe2O3. Overall, the gas-sensing performance of the α-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 α-Fe2O3-MWCNTs heterojunction.