Metal-organic frameworks derived hierarchical flower-like ZnO/ Co3O4 heterojunctions for ppb-level acetone detection

The demand of acetone gas sensors with great response value and fast response/recovery time to low concentration acetone is increasing in practical diagnosis for diabetes. In this work, metal-organic frameworks (MOFs) derived flower-like ZnO/Co3O4 heterojunctions based sensor is prepared by a simple solution mixing method at room temperature. The sensor shows high acetone response value, short response/recovery time, excellent selectivity and good stability. For example, the response value of ZnO/Co3O4 heterojunctions based sensor is up to 120 % towards 500 ppb acetone at 300 ℃, which is about 30-fold enhancement than these of intrinsic ZnO and Co3O4. Moreover, its minimal detection limitation is 100 ppb acetone and it shows ultra-fast response/recovery time for ppb-level acetone (22 s/27 s@500 ppb). The excellent acetone sensing properties of flower-like ZnO/Co3O4 heterojunctions based sensor is attributed to the sharp resistance variation of heterojunction interface between ZnO and Co3O4 and the ultra-fast gas transport channel provided by ZnO nanosheets. This finding provides important insights and useful guidance for the detection of ppb-level acetone.