Electrodeposition of gold nanoparticles from ionic liquid microemulsion

Abstract

Gold nanoparticles were electrodeposited directly for the first time from a new electrolyte system: water-in-ionic liquid (W/IL) microemulsion. The electrochemical behavior of Au(Ш) in W/IL microemulsion was investigated. The cyclic voltammetry (CV) result of Au(Ш) shows a pair of redox peak. The effect of precursor apparent concentration on the reduction peak current density is similar to that in homogeneous solution such as aqueous solution. The effect of scan rate on the reduction peak current density is different from that in homogeneous solution. Linear-sweep voltammograms result for a rotating disk electrode in the W/IL microemulsion suggests that the reduction is kinetically limited and not transport limited. And also the activation energy of the reaction was calculated to be 26.7 KJ mol−1. The gold electrodeposits were characterized by scanning electron microscopy and X-ray diffraction. It is found that the gold electrodeposits are face-centered cubic and nanosized. Furthermore, the potential mechanism for the electrode reaction was proposed. In addition, the electrochemical properties of the gold nanoparticles were researched through the electro-oxidation of glycerol. The CV and electrochemical impedance spectroscopy studies demonstrate that the gold nanoparticles electrodeposited from W/IL microemulsion have much higher electro-catalytic activities than bare gold for glycerol oxidation.