Calcination-temperature-dependent gas-sensing properties of mesoporous α-Fe2O3 nanowires as ethanol sensors

The mesoporous α-Fe₂O₃ nanowires (NWs) were successfully synthesized by changing the calcination temperature from 550 to 750 °C (marked NWs-550, NWs-650 and NWs-750) via using SBA-15 silica as the hard templates with the nanocasting method. The characterization results indicated that the bandgap of the as-prepared samples hardly changed and the high BET surface areas changed a little with the calcination temperature from 550 to 750 °C. Mesoporous α-Fe₂O₃ NWs had been found to possess the remarkable gas-sensing performance to ethanol gas. The gas-sensing behavior indicated that α-Fe₂O₃ NWs-650 exhibited the higher response than that of α-Fe₂O₃ NWs-550 and α-Fe₂O₃ NWs-750. The calcination-temperature-dependent gas-sensing properties were mainly attributed to the competition of surface defects and body defects by the crystallization temperature. The lower calcination temperature could create more surface defects to improve the gas-sensing response, while the higher temperature would reduce the body defect and make the charge carriers transport easily. As the result, the suitable calcination temperature was desired to optimize the defects of nanostructures to improve the gas sensitivity.