Electropolymerization of Aniline onto Anodic WO₃ Film: An Approach to Extend Polyaniline Electroactivity Beyond pH 7

Abstract

Generally, the redox activity of polyaniline (PANI) can only be retained in acidic media at pH < 3. This high acidity requirement has been a large obstacle in many applications such as biosensor, marine antifouling, and anticorrosion. In this study, composite film systems of PANI and tungsten trioxide (WO3) were fabricated by the electropolymerization of aniline onto anodic WO3 film. For the first time, we found that the prepared PANI/WO3 film possesses excellent electrochemical activity and cycling stability in neutral solutions. The morphology and composition of the PANI/WO3 films were characterized by scanning electron microscope (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), and X-ray photoelectron spectroscopy (XPS), whereas their electroactivity was evaluated by cyclic voltammetry. Particularly, the long-term stability of their electroactivity upon cycling was investigated in detail. The good electroactivity and high redox stability of the PANI/WO3 films in neutral media can be ascribed to the intercalated H+ ions into WO3 film during electropolymerization of aniline. Moreover, the reduced electroactivity of the PANI/WO3 films can be recovered readily by cyclic voltammetry in an acidic solution. This study provides a new method to tune the electroactivity of PANI beyond pH 7 and makes PANI a promising candidate for biosensors.

Shape Evolution of Hierarchical W₁₈O₄₉ Nanostructures: A Systematic Investigation of the Growth Mechanism, Properties and Morphology-Dependent Photocatalytic Activities

“…The binding energies of the W 4f peaks at 35.21 eV and 37.16 eV can be assigned to 4f7/2 and 4f5/2 of W 5+ , respectively. Moreover, two additional small peaks centered at 34.20 eV (W4f7/2) and 36.19 eV (W4f5/2) are attributed to the W 4+ oxidation state [6,[18][19][20]. The presence of lower oxidation state (W 4+ ) further confirmed the formation of non-stoichiometry W18O49 [21].…”

Enhanced photoelectrochemical performance of WO3 film with HfO2 passivation layer

“…In Fig. 4, in the case of pure WO 3 , two intensive peaks at 850.47 and 781.04 cm -1 are assigned to the stretching mode of WeOeW in WO 3 [47]. The absorption peaks at 3440 and 1633 cm -1 are ascribed to OeH stretching vibrations arising from hydroxyl groups [48].…”

On the electrochemical synthesis and charge storage properties of WO3/polyaniline hybrid nanostructures

“…Furthermore, the preservation of WO 3 -related redox peaks in the hybrid may indicate that the underlying nanoporous WO 3 is still accessible to H + from the solution phase. Alternatively, the deposited PANI may be acting as a relay layer for the transport of H + [34]; however, from CV results alone, differentiation of these two different mechanisms is not possible.…”