Electrochemical polymerization of o-phenylenediamine in the presence of metal salts: influence of Cu(NO3)2 and AgNO3 on spectroelectrochemical properties and morphology

Abstract

In this study, the effects of adding Cu(NO3)2 and AgNO3 metal salts to the polymerization medium on the electrochemical and spectroelectrochemical properties of poly(o-phenylenediamine) (PoPD) were investigated. It was observed that the presence of Cu(NO3)2 or AgNO3 during polymerization increased the rate of current peak growth, indicating an acceleration of the polymerization process in the presence of metal ions. The cyclic voltammetry responses of the metal/polymer composites differed significantly from those of the pure polymer, confirming the formation of metal/polymer composites. FTIR and UV-vis absorption spectra were analyzed to explore the chemical structure of PoPD, PoPD/Cu, and PoPD/Ag polymer films. SEM and AFM analyses revealed distinct morphological differences between the polymer synthesized in the presence of metal salts and the pure polymer. Spectroelectrochemical analyses demonstrated that the polymer films exhibited reversible color changes from light copper to green, with distinct optical intensities in the UV-vis spectra. The absorbance and current values changed reversibly with the applied potential, with response times of approximately 10 s. Colorimetric analysis based on the CIE system showed unique variations in brightness (L), magnitude (a), and intensity (b) for PoPD, PoPD/Ag, and PoPD/Cu, confirming distinct colorimetric shifts during redox transitions. This study highlights the impact of Cu and Ag salts on the spectroelectrochemical and electrochromic performance of PoPD, revealing potential applications for PoPD composites in advanced electrochromic devices.