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

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 center dot 2H2O molar ratio of 2.451 exhibits significantly enhanced electrochemical performance, demonstrating fast reaction kinetics for Li+ ions (diffusion coefficient = 1.08 x 10-9 cm2 s-1) compared to the pristine WO3 thin film (diffusion coefficient = 1.42 x 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. A WO3 thin film prepared with a CTAB/Na2WO4 center dot 2H2O molar ratio of 2.451 exhibits considerably improved current density, charge storage capacity, and diffusion kinetics.