Facile Synthesis of Self-Assembled NiFe Layered Double Hydroxide-Based Azobenzene Composite Films with Photoisomerization and Chemical Gas Sensor Performances

Two kinds of layered double hydroxide (LDH) Langmuir composite films containing azobenzene (Azo) groups were successfully prepared by Langmuir–Blodgett (LB) technology. Then, an X-ray diffractometer (XRD), a transmission electron microscope (TEM), and an atomic force microscope (AFM) were used to investigate the structures of NiFe-LDH and the uniform morphologies of the composite LB films. The photoisomerization and acid–base gas sensor performances of the obtained thin film samples were tested by infrared visible (FTIR) spectroscropy and ultraviolet visible (UV–vis) spectroscropy. It is proved that the Azo dye molecules in the composite film are relatively stable to photoisomerization. In addition, the prepared composite films have high sensing sensitivity and good recyclability for acid–base response gases. The present research proposes a new clue for designing thin film materials for chemical gas response with good stability and sensitivity.