Fast-response hydrogen sulfide gas sensor based on electrospinning Co3O4 nanofibers-modified CuO nanoflowers: Experimental and DFT calculation

In this paper, copper oxide nanoflower/cobalt tetroxide nanofiber (CuO/Co3O4) composites are synthesized by hydrothermal method and electrospinning technology, and a high-performance gas sensor for H2S is successfully prepared. The morphology, microstructure and elemental composition of the materials are characterized by XRD, SEM, TEM and XPS. The CuO/Co3O4 sensor has the best response to H2S when the mass percentage of Co3O4 is 25 wt%, and the response is the highest at the operating temperature of 200 °C. By comparison, CuO/Co3O4 sensor has higher response (194 %@25 ppm) and faster response/recovery time (6 s/25 s@25 ppm) at the optimum temperature. It also has excellent repeatability, long-term stability and selectivity. According to the analysis, the improvement of H2S gas sensing properties of CuO/Co3O4 sensor is mainly due to the larger specific surface area brings more active sites, which promotes the adsorption of gas on the material surface. At the same time, the p-p heterojunction at the contact interface of CuO/Co3O4 nanocomposites also plays a very important role. In addition, theoretical calculation based on the first principle further reveals the improvement of H2S gas sensing performance of CuO/Co3O4 nanocomposites.