Indium oxide-black phosphorus composites for ultrasensitive nitrogen dioxide sensing at room temperature

•m-BP successfully incorporate in In2O3 nanorods, developing the hetero-structured BP-In2O3 composites.•BP-In2O3 exhibits the better sensing properties to NO2 compared to In2O3 and the reported BP-based materials.•These properties are due to large surface area, excellent carrier mobility and enhanced chemisorbed oxygen in presence of BP. In2O3 nanorods were successfully incorporated by different amount of multi-layer black phosphorus (m-BP), forming the hetero-structured BP-In2O3 composites. The structure, morphology and composition of the as-synthesized composites were characterized by X-ray diffraction (XRD), field-emission electron microscopy (FESEM), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). Interestingly, the environmental stability of BP can be notably improved by the introduction of In2O3. Moreover, NO2 sensing properties of BP-In2O3 composites were tested at room temperature (25 °C) with relative humidity of 30%. It is demonstrated that the sensor based on BP-In2O3 composites exhibits high response, lower detect limit, short response-recovery time and outstanding selectivity at room temperature. Such sensing behavior can be attributed to high adsorption capacity to NO2, large surface area, excellent carrier mobility of BP-In2O3 in presence of BP, as well as high concentration of chemisorbed oxygen on the In2O3 surface derived from electrons transfer from BP to In2O3.