Cyclic voltammetric study of zinc and zinc oxide electrodes in 5.3 M KOH

The behaviour of zinc and zinc oxide in 5.3 M KOH in the presence of alkali ne earth oxides, SnO, Ni(OH)(2) and Co(OH)(2) was examined by cyclic voltam metry. The influence of the alkaline earth oxides was compared with additiv es of established effects (Bi2O3, LiOH, Na2CO3 and CdO). The alkaline earth oxide each exhibits a distinct behaviour towards zincate. Whereas, a singl e process of interaction with zincate was shown by CaO; two modes of reacti on were obtained with SrO and BaO. Solid solution formation was noticed wit h BeO and MgO. The other additives forming solid solution with ZnO were CdO , SnO. The ionic sizes of Ni(OH)(2) and Co(OH)(2) allow solid solution form ation with Zn(OH)(2). Both Bi2O3 and Na2CO3 enter into complexation with zi ncate. LiOH forms two distinct zincates, of which one is an oxo zincate lea ching the 'hydroxyl' functionality. Cyclic voltammetry revealed the deposit ion of the oxide/hydroxide additives as metal prior to the onset of zinc de position and the potential range for this additive metal deposition is almo st the same for different additives (SnO, CdO, Ni(OH)(2)). The beneficial a ction of these additives to zinc alkaline cells is associated with a substr ate effect. The implication of this electrocatalytic deposition of metals o n a zinc oxide electrode is also discussed.