Electrodeposition of Gold at Glassy Carbon Electrodes in Room-Temperature Ionic Liquids

Abstract

The cyclic voltammetric behavior of [normalAuCl4]− on glassy carbon (GC) and gold electrodes in room-temperature ionic liquids, i.e., 1-ethyl-3-methylimidazolium tetrafluoroborate (EMIBF4) and 1- n -butyl-3-methylimidazolium tetrafluoroborate (BMIBF4) has been examined. A series of two-electron (2e-) and one-electron (1e-) reductions of the [AunormalCl4]−–[AunormalCl2]−–Au redox system could be observed at GC electrode. For example, the cathodic and anodic peaks corresponding to the [AunormalCl4]−∕[AunormalCl2]− redox couple were observed at ca. 0.2 and 1.2V vs a Ag wire quasi-reference electrode, respectively, in EMIBF4 , while those observed at −0.5 and 0.5V were found to correspond to the [AunormalCl2]−∕Au redox couple. The disproportionation reaction of the 2e-reduction product of [normalAuCl4]− , i.e., [normalAuCl2]− to [normalAuCl4]− and Au metal, was also found to occur significantly. A single reduction peak corresponding to the three-electron (3e-) reduction of [normalAuCl4]− to Au metal was observed at Au electrode. The electrodeposition of Au nanoparticles was carried out on GC electrode in these ionic liquids containing [normalAuCl4]− by applying potential-step electrolysis in a different potential range, i.e., the potential was stepped from 0.4V to 0 and −1.0V , at which the reduction of [normalAuCl4]− to [normalAuCl2]− and Au, respectively, takes place. The results obtained demonstrate that the electrodeposition of gold may occur via a disproportionation reaction of [normalAuCl4]− to [normalAuCl2]− and Au as well as via a series of the reductions of [normalAuCl4]− to [normalAuCl2]− and further, [normalAuCl2]− to Au. The size and morphology of the prepared Au nanoparticles as well as the relative ratio of the Au(111), Au(110), and Au(100) crystalline orientation domains constituting the polycrystalline Au nanoparticles electrodeposited were found to largely depend on the stepped potential (i.e., 0 and −1.0V ). Interestingly, the Au nanoparticles prepared by a potential-step electrolysis from 0.4to0V are enriched in the Au(110) single-crystalline domain.

Electrodeposition of a Au-Dy2O3 Composite Solid Oxide Fuel Cell Catalyst from Eutectic Urea/Choline Chloride Ionic Liquid

“…The positive current density increase at potentials more anodic than ca. 0 V corresponds to Au oxidation [24][25][26]. From these voltammetric data, the potential of −1.8 V has been chosen for Au-Dy alloy electrodeposition: in correspondence of this potential in fact both Dy and Au might be deposited and this condition not yet leads to reduction of the ionic liquid.…”

Electrocatalytic Reduction of Hydrogen Peroxide on Palladium-Gold Codeposits on Glassy Carbon: Applications to the Design of Interference-Free Glucose Biosensor

“…The second approach is often preferred due to the possibility of strict and accurate control allowing for the high reproducibility of the modification procedure. Contemporary studies proved the electrodeposition as an attractive and cheap method for building-up nanosized metal structures, which does not require expensive equipment [27,28]. By varying the conditions of modification (applied potential, composition of the electrolyte, deposition time, nature of the carrier, etc.…”

Electrochemical Quantification of Hygroscopicity of Ionic Liquids with Solution‐Dissolved Potassium Ferricyanide as the Redox Probe

“…They have emerged as one kind of the most potential candidates to replace traditional organic solvents and have drawn a great deal of attention over the past two decades because of their unique physical and chemical properties, such as negligible vapor pressure, high chemical and thermal stability, and wide potential window [1][2][3][4][5][6]. These properties have successfully enabled ILs to be widely used in various research and industrial fields, such as organic synthesis, electrochemistry, biocatalysis, and chemical engineering [7][8][9][10][11][12][13][14][15].…”