▎ 摘　　要

Layered double hydroxides (LDHs) have been demonstrated to be promising gas-sensing materials because of their high specific surface area and unique layered structure. However, the general stacking and low conductivity make the LDHs insensitive in most cases towards rarefied gas exposure. In this work, we designed and hydrothermally prepared nanocomposites of LDHs/rGO (layered double hydroxides/reduced graphene oxide) based on electrostatic self-assembly. The as-formed nanocomposite with proper addition of GO shows loose arrangement of LDH nanoflakes on both sides of the highly conductive rGO instead of the stacked flower-like structure of pure LDHs. The unique microstructure, as well as the conductivity modulation by rGO, induces enhanced sensing performance of the LDHs/rGO nanocomposites compared with that of the pure ZnTi-LDHs. At room temperature, the sensor based on LDHs/rGO is responsive to rarefied NO2 low to 50 ppb and 4-fold enhancement in gas response is achieved upon 0.5-50 ppm NO(2)exposure in comparison to that of the single ZnTi-LDHs sensor. Meanwhile, the LDHs/rGO sensors show near instantaneous response characteristics and good stability. The satisfactory sensing response of LDHs/rGO is analyzed in terms of the unique guided-assembly microstructure and the synergistic contributions on gas-sensing and conductivity properties of ZnTi-LDHs and rGO.