Synthesis of hierarchically porous Co3O4/Biomass carbon composites derived from MOFs and their highly NO2 gas sensing performance

The hemp stems biomass carbon (BC) with good electrical conductivity and the hierarchical structure was used as the carrier, based on the principles of green chemistry and sustainable development. The CoBC composites were synthesized by in-situ growth of porous hollow concave Co3O4 dodecahedron (PHCD Co3O4) synthesized with MOF template through vacuum-assisted and calcination methods. The CoBC-700 composite shows an excellent response to 100 ppm of NO2 gas (Ra/Rg = 34.1) and has excellent repeatability and considerable long-term stability at room temperature. The biomorphic hierarchical structure of BC effectively enhances the dispersibility of the PHCD Co3O4, which increases the contact area with the target gas molecules. The contact between BC and PHCD Co3O4 enhances the electron transfer of the material during the sensing process, which effectively improves the sensor performance at lower operating temperatures. Facts have proved that using CoBC-700 composite to assembly NO2 gas sensors was a promising strategy. [Display omitted] •Co3O4/Biomass carbon (CoBC) sensor was fabricated by a simple in situ growth method.•Realized the upgrade utilization of biological waste.•The special porous structure of CoBC increases the reaction sites with the gas to be measured.•The synergy between the two phases can effectively improve the carrier mobility.•The CoBC sensor shows excellent performance for NO2 sensing.