| 要約: | As a typical spinel ferrite, NiFe<sub>2</sub>O<sub>4</sub> is suitable for use in gas sensors. Herein, we report the fabrication of porous, tremella-like NiFe<sub>2</sub>O<sub>4</sub> assembled using porous, ultrathin nanosheets via the coordination of Ni<sup>2+</sup> and Fe<sup>2+</sup> with 1,4-phenylenediboronic acid. The optical band gap of the NiFe<sub>2</sub>O<sub>4</sub> is estimated to be about 1.7 eV. Furthermore, the NiFe<sub>2</sub>O<sub>4</sub> sensor annealed at 400 °C exhibits a low detection limit of 50 ppb, a fast response/recovery time (11.6 s/41.9 s to 10 ppm toluene), good reproducibility, and long-term stability at 220 °C. The suitable sensing performances can be attributed to the good catalytic activity of NiFe<sub>2</sub>O<sub>4</sub> to toluene oxidation. Moreover, the ultrathin nanosheets with porous structures provide a large number of active sites to significantly favor the diffusion and adsorption/desorption of toluene molecules. This current work provides an insight into fabricating NiFe<sub>2</sub>O<sub>4</sub> using 1,4-phenylenediboronic acid, which is promising for ppb-level toluene detection.
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