An Aqueous Exfoliation of WO₃ as a Route for Counterions Fabrication—Improved Photocatalytic and Capacitive Properties of Polyaniline/WO₃Composite

In this paper, we demonstrate a novel, electrochemical route of polyaniline/tungsten oxide (PANI)/WO₃) film preparation. Polyaniline composite film was electrodeposited on the FTO (fluorine-doped tin oxide) substrate from the aqueous electrolyte that contained aniline (monomer) and exfoliated WO₃ as a source of counter ions. The chemical nature of WO₃ incorporated in the polyaniline matrix was investigated using X-ray photoelectron spectroscopy. SEM (scanning electron microscopy) showed the impact of WO₃ presence on the morphology of polyaniline film. PANI/WO₃ film was tested as an electrode material in an acidic electrolyte. Performed measurements showed the electroactivity of both components and enhanced electrochemical stability of PANI/WO₃ in comparison with PANI/Cl. Thus, PANI/WO₃ electrodes were utilized to construct the symmetric supercapacitors. The impact of capacitive and diffusion-controlled processes on the mechanism of electrical energy storage was quantitatively determined. Devices exhibited high electrochemical capacity of 135 mF cm⁻² (180 F g⁻¹) and satisfactory retention rate of 70% after 10,000 cycles. The electrochemical energy storage device exhibited 1075.6 W kg⁻¹ of power density and 12.25 Wh kg⁻¹ of energy density. We also investigated the photocatalytic performance of the deposited film. Photodegradation efficiencies of methylene blue and methyl orange using PANI/WO₃ and PANI/Cl were compared. The mechanism of dye degradation using WO₃-containing films was investigated in the presence of scavengers. Significantly higher efficiency of photodecomposition of dyes was achieved for composite films (84% and 86%) in comparison with PANI/Cl (32% and 39%) for methylene blue and methyl orange, respectively.