Construction of composite thin films via layer-by-layer electrostatic self-assembly of chitosan/phosphotungstate acid

Chitosan (CTS) and phosphotungstate acid (PTA) were fabricated on solid substrates by means of layer-bylayer electrostatic self-assembly technique (LBL). The resulting films were characterized by UV-Vis, FTIR, XPS, atomic force microscopy (AFM) and cyclic voltammetry (CV) measurements. UV-Vis spectra show that the absorbance values at characteristic wavelengths of the multilayer films increase almost linearly with the number of chitosan/PTA bilayers, suggesting that the deposition process is regular and highly reproducible from layer to layer. XPS and FTIR spectra confirm the incorporation of chitosan and PTA into the films. AFM images indicate that the surface of the multilayer films is rough. The result of CV shows that the multiplayer films maintain good electrocatalytic activity of phosphotungstate acid.