Ultrasensitive and ultraselective detection of H₂S using electrospun CuO-loaded In₂O₃ nanofiber sensors assisted by pulse heating

Pure and CuO-loaded In₂O₃ nanofibers were prepared by electrospinning and their H₂S sensing characteristics were investigated. The loading of CuO on In₂O₃ nanofibers significantly enhanced the gas response (ratio of the resistance in air to that in gas) toward 5 ppm H₂S from 515 to 1.16 × 10⁵ at 150 °C. The CuO-loaded In₂O₃ nanofibers also exhibited high gas response (9.17 × 10³ toward 5 ppm H₂S) at room temperature. The CuO-loaded In₂O₃ nanofibers showed ultrahigh selectivity to H₂S concerning interferences with NO₂, H₂, CO, NH₃, C₂H₅OH, C₃H₆O, TMA, C₇H₈, and C₈H₁₀ at room temperature and 150 °C. The operation of the sensor using pulse heating was suggested reliable H₂S sensing with complete recovery. The ultrasensitivie and ultraselective H₂S sensing characteristics are explained in terms of the creation and disruption of p-n junctions in the presence and absence of H₂S, respectively, the high specific surface area provided by the networks of one-dimensional polycrystalline nanofibers, and the abundance of p-n junctions due to the uniform mixing between p-CuO and n-In₂O₃ nanograins within the nanofibers.