Electrodeposition of nanoscaled nickel in a reverse microemulsion

A novel method for preparing conductive water-in-oil (W/O) microemulsion and nanodeposit was introduced. The conductivity of the W/O microemulsion is increased by increasing the H+ concentration of the water phase. When the H+ concentration of the water phase reaches 10 mol L-1, the conductivity of the W/O microemulsion goes up to 1 mS cm(-1). Thus modified W/O microemulsion has conductivity similar to a diluted electrolyte aqueous solution, which makes it possible for the W/O microemulsion to be used as an electrolyte for electrodeposition. By direct electrodeposition in the W/O microemulsion, nickel nano-particles were modified onto the nickel substrate. The cathodic process of Ni2+ in the W/O microemulsion was studied by linear sweep voltammetry and electrochemical impedance spectroscopy. The results indicate that the electrode process at the electrode/microemulsion interface is quite different from that at the electrode/aqueous solution interface. Scanning electron microscopy measurement shows that the deposited nickel particles have spherical morphology with diameter about 40 nm. The electrochemical reactivity of the nickel nano-particles modified electrode was measured in acid system. It is found that the electrochemical reactivity of the nickel nano-particles modified electrode is different obviously from that of the normal watts-nickel modified electrode. (C) 2006 Elsevier B.V. All rights reserved.