Synthesis and Electroanalytical Performance of a Composite Material Based on Poly(3,4-ethylenedioxythiophene) Doped with Lignosulfonate

3,4-ethylenedioxythiophene (EDOT) was electropolymerized in the presence of sodium lignosulfonate (LS) at constant current density of 0.25？mA？cm？2. As a result, a thin composite film consisting of poly(3,4-Ethylenedioxythiophene) and LS (PEDOT/LS) was deposited on the electrode surface. Unlike PEDOT, PEDOT/LS shows appreciable redox activity due to LS-derived quinone moieties with diffusion-like charge propagation across the film thickness. The film-modified gold electrodes can be used as voltammetric sensor of uric acid (UA) in the presence of ascorbic acid (AA). Interestingly, the UA response is catalysed by the presence of AA, and for high AA/UA concentration ratios more than 10-fold enhancement of the UA peak currents are apparent. 1. Introduction Conducting polymers (CPs) have been attracting attention of material scientists and electrochemists for many years because of their easy preparation, high electroconductivity, as well as attractive electrochemical and optical properties [1]. Properties of CPs are to some extend a function of the counterion balancing the positive charge of the protonated conjugated polymer chains. Therefore, various sulfonated compounds have been successfully applied to dope conducting polymers and thus to tune their properties. Among those sulfonic acids [2], sulfonated phthalocyanines [3], sulfonated anthraquinone and benzoquinone derivatives [4, 5], and sulfonated polymers [6–9] are the most representative examples. On the other hand, lignosulfonates (LSs) obtainable in huge quantities as a byproduct of pulp and paper industry attracted rather little attention as dopants of CPs. For instance, Roy et al. [10] used lignosulfonate as polyanion to dope chemically synthesized polyaniline. Similarly LS was used as dopant for polypyrrole [11]. Other electrochemical applications of LSs were also reported. For example, Vagin et al. electropolymerized LS on steel and showed anticorrosion properties of thus formed thin film. The same authors also studied electrochemistry of lignosulfonate on glassy carbon and reported it not to undergo electropolymerization on this electrode [12]. Contrary to the latter observation, we electropolymerized LSs from an acidic electrolyte on preactivated glassy carbon and observed high redox activity of the formed coatings which could be practically applied in the electrocatalytic reduction of acidic nitrite [13] or electrocatalytic oxidation of NADH [14]. We also proved that LSs can be used as valuable electrolyte additives in electrochemical supercapacitors [15]. The aim of the present work is to