High sensitivity and wide range flexible piezoresistive sensor based on petal-shaped MOF-derived NiCo-NPC

Due to the advantages of high porosity, excellent conductivity, and tunable morphology, carbonized metal-organic framework (C-MOF) is expected to become an ideal material for constructing high-performance flexible pressure sensor. Herein, to achieving the suitable morphology of C-MOF for piezoresistive sensors, a rapid thermal process (RTP) was used for carbonization of NiCo-MOF, and the petal-shaped NiCo alloy nanoparticles/nanoporous carbon composites (NiCo-NPCs) were obtained. Compared with NiCo-NPCs carbonized by common thermal process (CTP), NiCo-NPCs carbonized by RTP exhibit a modified morphology with smaller particle size and larger most frequent pore diameter. Due to the modified morphology, the piezoresistive sensor with RTP-carbonized NiCo-NPCs has a high sensitivity of 62.13 kPa^-1at 0-3 kPa, which is 3.46 times higher than that of the sensor with CTP-carbonized NiCo-NPCs. Meanwhile, the sensor shows an ultra-wide range of 1000 kPa, excellent cycle stability (>4000 cycles), and fast response/recovery time of 25/44 ms. Furthermore, the application of the sensor in dynamic loading test, airflow monitoring, voice recognition, and gesture detection demonstrates its great application prospects. In short, this work investigates the application of carbonized NiCo-MOFs in flexible pressure sensors, and provides a new strategy to improve the performance of piezoresistive sensors with porous carbon derived from MOFs.