Electrospun Cu-doped In₂O₃ hollow nanofibers with enhanced H₂S gas sensing performance

One-dimensional nanofibers can be transformed into hollow structures with larger specific surface area, which contributes to the enhancement of gas adsorption. We firstly fabricated Cu-doped In₂O₃ (Cu-In₂O₃) hollow nanofibers by electrospinning and calcination for detecting H₂S. The experimental results show that the Cu doping concentration besides the operating temperature, gas concentration, and relative humidity can greatly affect the H₂S sensing performance of the In₂O₃-based sensors. In particular, the responses of 6%Cu-In₂O₃ hollow nanofibers are 350.7 and 4201.5 to 50 and 100 ppm H₂S at 250 ℃, which are over 20 and 140 times higher than those of pristine In₂O₃ hollow nanofibers, respectively. Moreover, the corresponding sensor exhibits excellent selectivity and good reproducibility towards H₂S, and the response of 6%Cu-In₂O₃ is still 1.5 to 1 ppm H₂S. Finally, the gas sensing mechanism of Cu-In₂O₃ hollow nanofibers is thoroughly discussed, along with the assistance of first-principles calculations. Both the formation of hollow structure and Cu doping contribute to provide more active sites, and meanwhile a little CuO can form p-n heterojunctions with In₂O₃ and react with H₂S, resulting in significant improvement of gas sensing performance. The Cu-In₂O₃ hollow nanofibers can be tailored for practical application to selectively detect H₂S at lower concentrations.