High performance humidity sensor based on 3D mesoporous Co3O4 hollow polyhedron for multifunctional applications

In this work, the three-dimensional (3D) hollow mesoporous Co 3 O 4 was successfully prepared by calcining the Co-based zeolitic imidazolate framework-67 (ZIF-67). As-obtained Co 3 O 4 inherited the rhombohedral framework structure of ZIF-67 and possessed mesoporous and hollow structure. Further, the humidity sensor based on Co 3 O 4 was fabricated, and its humidity sensing properties were investigated at room temperature (25 °C). The results indicated that the Co 3 O 4 humidity sensor exhibited high humidity sensing performance with a wide linear detection range (10%−95% relative humidity (RH)), small humidity hysteresis (2.6% RH), and fast response/recovery times (1.0/13.5 s). In particular, the Co 3 O 4 humidity sensor was of high detection resolution (1% RH). The excellent performance was attributed to the strong hydrophilicity and the unique 3D porous structure of Co 3 O 4 . In addition, the potential applications of the fabricated Co 3 O 4 humidity sensor in skin humidity, simulated diaper, human breathing, and non-contact switch were demonstrated. This work provides a promising humidity sensing material for fabricating high-performance humidity sensors.