MOF-templated controllable synthesis of α-Fe2O3 porous nanorods and their gas sensing properties

Abstract

α-Fe₂O₃ porous nanorods (PNRs) with controlled morphologies were simply synthesized by thermolysis of Fe-based metal–organic framework (MIL-88A) at 500 °C. The as-resulted α-Fe₂O₃ nanostructures were well preserved according to the original MIL-88A morphology. The results indicated that the amount of fumaric acid (FMA) was the key to adjust the morphologies of Fe–MOF precursors. With the amount of fumaric acid decreasing, the lengths of α-Fe₂O₃ nanorods increased from 800 nm to 6 μm, and the width remained nearly unchanged. Further experiments were conducted to explain the different gas sensing properties of the as-prepared α-Fe₂O₃ PNRs. The results indicated that the high sensitivity of sample S1 was mainly attributed to the relative higher specific surface area and higher percentages of oxygen vacancies (O_V) compared to the other samples. O_V in α-Fe₂O₃ PNRs as donors were beneficial to oxygen adsorption on the surface. In addition, the gas sensing mechanism of as-prepared α-Fe₂O₃ PNRs was also proposed.