Textural and electrochemical properties of Watts nickel-deposited titanium electrodes

The surface morphologies and crystalline structures of Watts nickel-deposited titanium electrodes obtained for different plating times or plating solutions with various pH values were examined by scanning electron microscopy (SEM) and X-ray diffraction (XRD). These textural results indicate that the Ni grains with Ni(111) and Ni(200) preferred orientations have spherical/paddy-like and cubic morphologies, respectively. The XRD results indicate that Ni(111) is the preferred orientation of a newly grown grain or a deposit from a plating solution with pH > 5.0. Voltametric behavior of the Ni(III)/Ni(II) transition as well as that in the hydrogen region and the ability for hydrogen evolution of these electrodes were compared by cyclic voltametry (CV) and log(i) - E relationships. These electrochemical results revealed that deposits with Ni(111) preferred orientation exhibit higher active sites/activities for both the hydrogen responses and the Ni(III)/Ni(II) transition.