Synthesis and characterization of Al-doped ZnO/CdO heterostructured nanocomposites for enhancing NO₂ gas sensing performance

In this study, both petal-shaped Al-doped (1 at%) ZnO (Al-ZnO) and Al-ZnO/CdO heterostructured nanomaterials were successfully designed and synthesized via a facile two-step hydrothermal method. Characterizations of crystallinity, morphology and composition were performed by XRD, HR-TEM, FE-SEM, EDS, XPS, and Raman. The results of XRD, HR-TEM, and XPS reveal that Al-ZnO/CdO materials grew well together and coexisted. The petal shaped Al-ZnO/CdO heterostructured nanocomposite with 2 mol% of CdO was exposed to NO₂, NH₃, CH₃COCH₃, C₂H₅OH, and H₂ at an optimal operating temperature of 200 °C. Compared with pure ZnO and Al-ZnO, the petal-shaped Al-ZnO/CdO heterostructured nanocomposite exhibited specifically high enhanced performances in response and selectivity for the NO₂ gas sensing. Moreover, the sensitivity to NO₂ displayed excellent linear dependence in the range of 0.5 ∼ 5 ppm, which shows promise in the detection of NO₂ using a petal-shaped Al-ZnO/CdO heterostructured nanocomposite-based sensor.