Cu2O template-assisted synthesis of porous In2O3 hollow spheres with fast response towards acetone

• Porous In2O3 hollow spheres have been successfully synthesized by using Cu2O spheres as active templates.
• The method can be employed for synthesizing other metal oxide hollow spheres.
• The mechanism for the formation of In2O3 hollow spheres was discussed based on Pearson׳s hard and soft acid–base principle.
• The as-prepared In2O3 hollow spheres exhibited good sensing performance towards acetone gas with rapid response.

Metal oxide semiconductors with hollow structure and morphology have attracted considerable attention because of their promising application as gas sensors. Based on Pearson׳s hard and soft acid–base (HSAB) principle, we have successfully prepared porous In2O3 hollow spheres by a template-assisted method using Cu2O as the sacrificial template. In(OH)3 hollow spheres as the precursor were prepared via simple chemical reactions, then In2O3 hollow spheres can be obtained by thermal decomposition of the precursor. The composition and morphologies of Cu2O templates and In2O3 products were characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), and transmission electron microscopy (TEM). The results suggest that the final products were pure In2O3 with the structure of hollow spheres, and the thickness of the spherical shell is about 15 nm. Finally, the gas sensor performance testing of In2O3 hollow spheres showed the excellent properties of rapid response towards acetone gas.

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