Excellent NO2 gas sensor based on the oxygen inhibiting effect of Ni3+-doped WO3

Abstract

Due to the intrinsic properties of wide band gap and the 5d shell being vacant, WO3 still has the disadvantages of low response dynamics, slow response/recovery speed and high detection limit for real-time gas monitoring. To address such issues, the Ni3+ doped WO3 hierarchical hollow structure composed of irregular nanosheets was achieved and the content of adsorbed oxygen was adjusted by Ni3+ doping to further improve the gas sensing performance of WO3. In comparison to pure WO3, the 3 wt%Ni-WO3 sensor exhibited remarkable response value (396), short response/recovery speed (13 s/6 s) and low detection limit (510 ppt) at 160 ℃. The impressive gas properties could be attributed to the reduced band gap and oxygen inhibiting effect of Ni3+ doping, which provides more NO2 adsorption sites and making it easier for NO2 to capture more electrons in the conduction band by restraining the oxygen ions chemisorbed on the surface. The unique sensing characteristics of the Ni3+ doped WO3 suggest its wonderful potential applications in environmental pollution gas detection. The mechanism of oxygen inhibiting effect induced by Ni3+ doping was also discussed in detail