Exploring the impact of a cetyltrimethylammonium bromide surfactant on the electrochemical performance of tungsten oxide thin films

Abstract

In this work, tungsten oxide (WO₃) thin films are grown on FTO glass using a facile spin coating method and an ink composed of WO₃ nanoparticles synthesized under varying concentrations of cetyltrimethylammonium bromide (CTAB) surfactant. The influence of variation of the CTAB concentration on the quality and electrochemical performance of the prepared WO₃ thin films is investigated. Cyclic voltammetry and electrochemical impedance spectroscopic analysis confirm that the thin film prepared with a CTAB/Na₂WO₄·2H₂O molar ratio of 2.451 exhibits significantly enhanced electrochemical performance, demonstrating fast reaction kinetics for Li⁺ ions (diffusion coefficient = 1.08 × 10⁻⁹ cm² s⁻¹) compared to the pristine WO₃ thin film (diffusion coefficient = 1.42 × 10⁻¹⁰ cm² s⁻¹) lacking any CTAB addition. These improved electrochemical characteristics of modified WO₃ thin films are attributed to the increased porosity and a higher electroactive surface area.