The electrochemical behaviour of a zinc electrode in dilute Solutions
containing Zn(II) and Ni(II) ions has been studied. It is shown, that
preferential deposition of the less noble Zn rather than Ni occurs due
to kinetic features of simultaneous Ni(II) and Zn(II) discharges both
under activation control. The simple modelling of the composition all
oy has been based on the component current densities described by firs
t order Butler-Volmer kinetics. A coplanar built-in antimony microelec
trode assembly for potentiometric investigations is presented. The dep
endences of pH values near the cathode surface (pHs) on working electr
ode potentials, obtained by using the above mentioned electrode are di
scussed. It is shown, that in the so-called 'anomalous' region of Zn-N
i alloy deposition pHs remained close to the bulk pH value (pHb). In t
he 'normal' region of alloy deposition pHs value exceeds pHb throughou
t deposition runs and the effects of electrical connection between ele
ctrodes are noted The possibility of bifunctional electrochemical film
formation in the so-called 'normal' region of Zn-Ni alloy deposition
is briefly discussed.