One-step preparation of silver electrodeposits from non-aqueous solvents

Abstract

http://172.20.145.48/elsevier_cbt/wp-login.php?loggedout=trueThis paper describes the Ag electrodeposition on platinum electrode in different deep eutectic solvents (DES) as electrolytes, such as choline chloride:ethylene glycol (ChCl:EG) and choline chloride:urea (ChCl:U), using a molar ratio of 1:2. Having a concentration of 0.05 mol L−1 of silver nitrate in each DES, the electrodeposition was studied using cyclic voltammetry (CV), which shown a sole reduction and oxidation processes. The electrodeposition temperature was also studied in both solvents, having the Ag+ ions reduction peak potential shifted to relative lesser negative values and the reduction peak current relatively increased if compared with room temperature (RT) voltammograms. Using the optimized voltammetric conditions of Ag electrodeposition, the cathodic yield reached >80% in all studied temperatures and DES solutions. Chronoamperometric experiments were conducted in order to achieve Cottrell plots for determination of Ag+ ions diffusion coefficient (Do) for all DES electrolytes and temperatures, and its magnitude order was around 10−7 cm s−1 due to viscosity of the DES. In order to study the Ag nucleation mechanism in both DES electrolytes, dimensionless Scharifker-Hills (SH) model was applied. The analysis showed that Ag electrocrystallization in ChCl:EG had an intermediate mechanism at 25 °C and 45 °C, while 70 °C presented an instantaneous behavior, and Ag electrodeposition in ChCl:U showed progressive electrocrystallization in 25 °C and instantaneous behavior at 45 °C and 70 °C. SEM images showed a distribution of sub-micrometer Ag particles over bulk Ag electrodeposit, suggesting that Ag+ ions deposition using ChCl:EG and ChCl:U DES as electrolytes can achieve electrochemical synthesis of Ag microparticles.