Sandwich-like porous α-Fe2O3 nanorod arrays/hexagonal boron nitride nanocomposites with improved high-temperature gas sensing

Abstract

Sandwich-like porous α-Fe2O3 nanorod arrays/hexagonal boron nitride (h-BN) nanocomposites were synthesized by low temperature hydrolytic precipitation method. The structure and morphology of nanocomposites were studied by field emission scanning electron microscopy, transmission electron microscopy, X-ray diffraction and X-ray photoelectron spectroscopy. The results show that α-Fe2O3/h-BN nanocomposites are composed of porous α-Fe2O3 nanorod arrays arranged on the h-BN nanosheets in an orderly manner. The gas-sensing properties of α-Fe2O3/h-BN nanocomposites and pure α-Fe2O3 were further investigated. The experimental results show that the response of α-Fe2O3/h-BN-based sensor to 50 ppm acetone at an optimum temperature of 320 °C is 10.2. While the response of the α-Fe2O3-based sensor is 5.6 at same conditions. In addition, the α-Fe2O3/h-BN sensor not only returns to the initial state in a short time after exposure to fresh air, but also has good selectivity. These significantly enhanced acetone sensing properties can be attributed to the fact that the prepared α-Fe2O3/h-BN nanocomposites have a large specific surface area, which are composited of porous α-Fe2O3 nanorods with a pore diameter of about 3.7 nm arranged in sequence on h-BN nanosheets. Secondly, the p–n junction between p-type h-BN and n-type α-Fe2O3 modulates the space charge layer at the interface between h-BN and α-Fe2O3.