Electrochromic Effect in Titanium Carbide MXene Thin Films Produced by Dip-Coating

MXenes, a large family of 2D transition metal carbides and nitrides, have shown potential in energy storage and optoelectronic applications. Due to the hydrophilic surface of MXenes, they can easily be processed in aqueous solutions at room temperature, allowing deposition onto lexible and stretchable substrates. Two thin films of similar transparency and sheet resistance were assembled in a three-electrode configuration to characterize the optoelectrochemical behavior. Similarly, in situ electrochemical Raman spectroscopy was performed in a three-electrode configuration. Using in situ X-ray diffraction (XRD) and in situ Raman spectroscopy, the mechanism of the electrochromic behavior has been attributed to the pseudocapacitive change of the MXene surface functionalities upon reduction. To study the electrochromic properties of the MXene thin films, symmetric three-electrode cells were used. The conditions followed for in situ Raman spectroscopy and XRD were the same conditions used for thin film characterization.