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 -Bi 2 O 3 has positive effect on the sensing performance of Bi 2 O 3 /ZnO composite.