fig6

Figure 6. (A) Schematic for the NO₂ sensing mechanism of CuO-PANI; (B) FT-IR spectra of CuO-PANI before and after exposure to NO₂; Illustration of the formation of the p-p heterojunction of CuO and PANI (C) before contact and (D) after contact, and (E) energy band diagram of CuO-PANI. PANI: Polyaniline; FT-IR: Fourier transform infrared spectroscopy.