Facile Preparation of CeO2 and Co3O4 Hollow Composite with Abundant Oxygen Vacancies and High Surface Area for Improved Acetone Sensing

Metal oxide semiconductor (MOS) based sensors are frequently used in acetone sensing, exhibiting great potential in diagnosing diabetes. Herein, a precoated silica layer is used to prevent the crystal grain growth during calcination of the precursor produced by solvothermal method, which may also leads to an auto-generated high pressure inside. These merits endow the as-prepared CeO2 and Co3O4 composite (denoted as CeO2Co3O4(SiO2)) with two times higher BET surface area than the counterpart without silica coating (CeO2Co3O4). Thanks to the small grain size and the in-situ formed anoxic micro-environment during calcination, more oxygen vacancies (O-v) are detected in CeO2Co3O4(SiO2). The CeO2Co3O4(SiO2) based sensor exhibits higher response, lower LOD and shorter response/recovery time than those of CeO2Co3O4. The superiority is mainly due to the larger surface area and more O-v of the CeO2Co3O4(SiO2), rather than the band gap structure. Moreover, the smaller grain size and more surface Co2+ species are also favorable.