Metal–organic framework-derived CuO tube-like nanofibers with high surface area and abundant porosities for enhanced room-temperature NO2 sensing properties

Metal–organic framework (MOF)-derived CuO microstructures suffer from low specific surface area and poor surface reactivity due to the severe agglomeration during calcination, which restricts their sensing response and reaction kinetics as gas sensors, especially at room-temperature (RT) manipulation. In this study, one-dimensional (1D) porous CuO tube-like nanofibers (TNFs) were constructed using a MOF approach combined with an electrospinning technique. The CuO TNFs displayed 1D hollow tubular structure with numerous cavities on the tube walls. In particular, these MOF-derived CuO TNFs interlaced with each other, forming a 3D netlike nanofiber structure with good anti-aggregation property. Compared with the MOF-derived CuO nanoparticles (NPs), the CuO TNFs had much better NO2 sensing characteristics in terms of great response (27.9-fold improvement @ 500 ppb), fast response/recovery rate, and high selectivity at RT (25 °C). The CuO TNFs also displayed reliable repeatability and good antihumidity. Sensing measurements under various oxygen partial pressures identified that Oads resulted in a decreased Ra, and had a negative effect on the improvement of NO2 response of CuO TNFs. The enhanced NO2 gas sensing properties of CuO TNFs were ascribed to their unique tube-like nanofiber network structure, high specific surface area, abundant porosities, and low activation energy.