Electrochemical Survey of Silver Nanoparticles-Lignosulfonate Formation and their Assessment in the Electrocatalytic Oxidation of P-Nitrophenol

Background: Metal nanoparticles have important applications in the field of electrochemical (bio) sensors by facilitating or amplifying the electronic transfer between electrode and target biologic compound, or acting as catalysts of electrochemical reactions. Silver nanoparticles are attracting great attention due to their (electro) catalytic properties, and subsequently their potential application in microelectronics, sensing devices and catalysis. The challenge of the silver nanoparticles synthesis consist in obtaining stable and small size nanoparticles, preventing unwanted agglomeration of the colloids and by using various natural polymers. Methods: In the preparation of silver nanoparticles, silver nitrate was taken as the metal precursor and sodium lignosulfonate was used as a reducing/stabilizing agent, considering that lignin derivatives are capable of complexing with silver cations and to reduce them to atomic silver. Cyclic voltammetry, differential pulse anodic stripping voltammetry and UV-vis spectrophotometry techniques have been involved in the evaluation of electrochemical and optical properties of silver nanoparticles. Results: The present work investigates the electrochemical aspects correlated with spectrophotochemical ones of silver nanoparticles prepared by a simple one step procedure and define their catalytic properties. The preparation of silver nanoparticles by a chemical reduction process via lignosulfonate was optimized in respect to their voltammetric behavior revealing the electrochemical characteristics of different silver nanoparticles. The resulting nanoparticles were characterized by means of cyclic voltammetry technique, in two forms: in bulk solution and immobilized as a layer on the electrode surface. The silver nanoparticles- lignosulfonate composites were found to exhibit efficient electrocatalytic activity toward the oxidation of p-nitrophenol. The response of the developed sensor to p-nitrophenol addition is assessed using faradaic peaks current measurements in cyclic voltammetry and differential pulse voltammetry techniques. Conclusion: The electrochemical and spectrophotometric evaluation of silver nanoparticles formation from silver salt and lignosulfonate, without using any other reducing or stabilizing agent and investigating both the effect of silver salt and lignosulfonate concentration. The lignosulfonate polymer demonstrated to be a good matrix for immobilization of silver nanoparticles onto screen-printed electrode and the resulting modified electrode exhibits efficient electrocatalytic activities toward the oxidation of p-nitrophenol.