ON THE SURFACE COVERAGE WITH ADATOMS DURING THE INITIAL NUCLEATION STAGES OF NICKEL DEPOSITION ONTO GLASSY-CARBON

The surface concentration of nickel adatoms during the initial stages of nucleation onto glassy carbon substrates has been determined by galvanostatic and potentiostatic pulse methods. It is established that nickel adatoms carry a partial positive charge of approximately 25%. The value of the diffusion coefficient of nickel adatoms is calculated to be D(a) almost-equal-to 1.25 x 10(-10) cm2 s-1, and the value of the diffusion overvoltage is found to be 0.5-1.5% of the overall overvoltage. The resistance of the surface diffusion process of adatoms R(d) = 0.147 OMEGA-cm2. The results obtained lead to the conclusion that at high overvoltages the rate-determining stage of the overall reaction of crystal growth might be the surface diffusion of adatoms, which is suppressed by the adsorption of 2-butyn-1,4-diol.