Influence of Nano-Al2O3 Particles on Nickel Electrocrystallization at Initial Stage

Abstract

Abstract The influence of nano-Al 2 O 3 particles on nickel deposition on copper matrix from acid sulphate solution was studied under various potentials (vs. SCE) by cyclic voltammetry (CV), chronoamperometry (CA) and electrochemical impedance spectroscopy (EIS). The results show that the beginning potential of Ni-Al 2 O 3 co-deposition is at −740 mV or so. The effect of nano-Al 2 O 3 particles on nickel deposition process may be different under various potentials. In the potentials range from −740 to −830 mV, Al 2 O 3 particles on cathode surface may be favorable for nickel deposition nucleation and promote electron crystallization nucleation because the induction period t m corresponding to the peak current of Ni-Al 2 O 3 co-deposition is apparently shortened, compared with that of pure Ni deposition. However, Al 2 O 3 particles adsorbed on cathode surface may obstruct electric discharge of partial ions and mass transmission process, resulting in the impedance increment of Ni-Al 2 O 3 co-deposition, especially in the potentials range from −250 to −650 mV. The favorable effect of Al 2 O 3 particles weaken in the range of high over potential, and the particles accumulated on electrode surface will decrease the reduction current of Ni-Al 2 O 3 deposition. At the potential −890 mV, the nucleation process of Ni-Al 2 O 3 co-deposition at initial stage follows the instantaneous model of Scharifker-Hill with three-dimensional fashion.