Carbon dots decorated hierarchical litchi-like In2O3 nanospheres for highly sensitive and selective NO2 detection

Carbon dots, being one of the zero-dimensional carbonaceous nanomaterials, possess numerous fancy characteristics in physics and chemistry, such as quantum size, abundant edges and functional groups, and high electrical conductivity, which are beneficial to gas sensing properties. It also has the advantages of low-cost and environmental-friendly preparation. In this work, carbon dots were employed as dopants for modification of hierarchical litchi-like In2O3 nanospheres via a facile and environment-friendly hydrothermal approach to improve the gas sensing properties. As-obtained products were characterized by X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, etc. Gas sensing properties of In2O3/carbon dots and pristine In2O3 were investigated systematically. As expected, the sensors based on the In2O3/carbon dots displayed enhanced response at working temperature of 50 degrees C, which was 4 times as high as the sensors based on the pristine In2O3. The sensors presented excellent selectivity. The enhancement of sensing properties should be mainly attributed to the heterojunctions constructed across the interface between the In2O3 and carbon quantum dots.