Cauliflower-shaped Bi2O3–ZnO heterojunction with superior sensing performance towards ethanol

Gas sensors based on metal oxide semiconductors have attracted great interest in the sensing of organic volatile compounds gas due to their easy fabrication, effective cost, and good stability. Herein, we rationally design ethanol gas sensors based on p-Bi2O3 and n-ZnO heterostructure with clear interfaces, which exhibit excellent response of 21.6 towards 100 ppm ethanol, wide concentration detection range from 1 to 500 ppm, working temperature as low as 175 °C, short response time of 7 s, and recovery time of 8 s at 100 ppm of ethanol. Moreover, the selectivity of Bi2O3/ZnO sensor towards ethanol is much better than that of other organic volatile gases. The relationship between the origin of superior sensing performances towards ethanol and the sharp interfaces of p-Bi2O3/n-ZnO heterostructure are also systematically investigated. On the other hand, it is also demnostrated that the tetragonal phase β-Bi2O3 has positive effect on the sensing performance of Bi2O3/ZnO composite. The cauliflower shaped Bi2O3/ZnO crystalline nanocomposite with uniform size of sub-micrometer were synthesized via the facile electrospinning and calcination routes. The gas-sensing performance of the composite was studied upon exposure to different concentrations of ethanol gas from 1 to 500 ppm at the optimum temperature (175 °C). Due to the existence of p-Bi2O3/n-ZnO heterojunction, the Bi2O3/ZnO sensor possesses ultra-high response of 50.0 towards 500 ppm, and excellent selectivity toward ethanol. Specifically, it can effectively work with long-term stability of as long as 60 days, compared to the pristine ZnO sensor. [Display omitted] •Novel cauliflower-shaped p-Bi2O3/n-ZnO material is prepared firstly for the ethanol sensor.•Bi2O3/ZnO sensor exhibits a short response time of 7 s at 175 °C, and wide detection range from 1 ppm to 500 ppm.•Introduction of heterojunction and the β-Bi2O3 phase can significantly improve the sensing performance.