A high-performance dual-function material: self-assembled super long α-Fe2O3 hollow tubes with multiple heteroatom (C-, N- and S-) doping

Abstract

Novel heteroatom self-doped super long α-Fe₂O₃ hollow tubes have been synthesized by the combination of hydrothermal and calcination techniques using the chicken eggshell membrane as a template and a dopant. The obtained α-Fe₂O₃ super long hollow tubes are composed of closely arranged building blocks (α-Fe₂O₃ nanorods), which are connected to each other and provide a lot of grain boundaries. Scanning electron microscopy, transmission electron microscopy, X-ray diffraction, Raman spectroscopy and nitrogen adsorption–desorption analysis were used to characterize the structure of the synthesized products. To demonstrate their potential applications, the as-synthesized samples were applied to ethanol (C₂H₅OH) gas sensors and supercapacitors. When applied as a gas sensor, the α-Fe₂O₃ material exhibits a high gas sensitivity, excellent recovery properties (9 s at 100 ppm C₂H₅OH concentration) and perfect selectivity to ethanol. As an electrode in a supercapacitor, α-Fe₂O₃ shows a high specific capacitance (330 F g⁻¹ at a current density of 0.5 A g⁻¹) with good cycling stability (64% maintained over after 2000 cycles). The excellent sensing and supercapacitor performances could be attributed to the unique super long hollow tubes combined with the abundant pore volume and the small amount of heteroatom doping.