Facile fabrication of multishelled Cr2O3 hollow microspheres with enhanced gas sensitivity

•Novel multishelled Cr2O3 hollow microspheres were prepared for the first time through a simple, low-cost and green self-templating approach.•The shells of multishelled Cr2O3 hollow microspheres are highly porous and made up of nanocrystals (5–25 nm).•Investigation of the formation mechanism reveals that the preheating program is vital to the formation of the multishelled structures.•The novel multishelled Cr2O3 hollow microspheres show significantly enhanced gas sensitive activity compared with their single-shelled hollow counterpart.

Novel multishelled Cr2O3 hollow microspheres (MCHMs) with diameters ranging from 1 to 3 μm have been successfully prepared through a simple, green and low-cost self-templating approach by simply modifying the post-calcination. The structure and morphology characteristics of the synthesized products were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Further experimental result reveals that the preheating program is vital to the formation of the multishelled architectures, and the formation process of the multishelled hollow microspheres was discussed in detail. More importantly, the multishelled Cr2O3 hollow microspheres (MCHMs) exhibit enhanced gas sensitive activity to ethanol compared with single-shelled Cr2O3 hollow structures.