Although tricobalt tetraoxide (Co3O4) exhibits excellent catalytic activity and selectivity towards CO, its inherent low response as a p-type semiconductor still needs further improvement. In this work, we report the synthesis of ultrathin nanosheet-assembled hierarchical CeO2/Co3O4 heterostructure with enhanced response towards CO through a facile solvothermal strategy using bimetallic MOFs as precursors. The results show that CeO2 nanoparticles are uniformly anchored on Co3O4 nanosheets, and the 5 mol % CeO2/Co3O4 (5CeO2/Co3O4) composite possesses a high specific surface area of 72.5 m2·g-1. Besides, the acquired 5CeO2/Co3O4 sensor achieves a high response of 184% ((Rg-Ra)/Ra) toward 50 ppm CO at 200 oC, which is about 4.4-fold higher than that of the bare sensor based on Co3O4. Meanwhile, the 5CeO2/Co3O4 sensor presents a low detection limit (300 ppb), short response time (13 s) and medium recovery time (48 s), good selectivity, reproducibility, and stability within 30 days. We speculate that the formed p-n heterojunctions between Co3O4 and CeO2 and abundant oxygen vacancies synergistically boost the sensing performances. Altogether, our synthetic approach for constructing nanosheet heterostructures and p-n heterojunctions is an effective strategy for developing highly sensitive p-type oxide semiconductors sensing materials.
