Analytical Evaluation of Optical pH-Sensitivity of Polyaniline Layer Electrochemically Deposited on ITO Electrode

The applicability of electrochemically deposited polyaniline (PANI) layer in the design of optical pH sensors has been evaluated in this research. PANI layer was electrochemically deposited by potential cycling on the surface of the indium tin oxide (ITO)-modified transparent electrode. The dependence of UV/Vis absorbance spectra of PANI layer on the pH has been evaluated. Significant pH dependence in optical absorbance at three peak maxima (at 455 nm, 630 nm and 855 nm) as well as the wavelength of maximum absorbance (λ max ) has been discussed. Taking into account an optical absorbance at different wavelengths and pH-dependent variation of absorbance peak maxima, the advantages and some limitations in pH determination by glass/ITO/PANI structure have been revealed and outlined. The sensitivity of PANI structure to the changes of pH by using different optical absorbance evaluation methods have been assessed and discussed. The applicability of combination of simultaneous determination of several here evaluated analytical signals has been foreseen.