Journal of Electroanalytical Chemistry, Vol.472, No.1, 53-63, 1999
Electrode kinetics and the nature of the metal electrode - Part 3. The Zn(II)/Zn electrode reaction studied at In plus Ga dropping (micro)electrodes
The reduction of Zn(II) from acidified aqueous 1 M NaClO4 solutions is studied at dropping In + Ga alloy electrodes containing up to 16.5 mol% indium. The standard potential of the Zn(II)/Zn(In + Ga) couple is found not to change significantly with the indium content of the electrode. The kinetic parameters of the reaction are determined by analysis of the quasi-reversible Zn(II) reduction waves obtained from dropping microelectrode measurements. The microelectrode results are confirmed by ac impedance analysis. The Zn(II) reduction proceeds via the same two-step electron transfer mechanism established earlier at mercury. Within the entire accessible potential range the rate constant of the first electron transfer step is rate determining and is found to decrease with the indium content of the electrode. This is discussed in terms of the effect of the indium concentration on the electronic properties of the electrode and of the electrode \ solution interface.
Keywords:LIQUID POLYVALENT ELEMENTS;DM-MU-E;NACLO4 SOLUTION;MERCURY;AMALGAMS;REDUCTION;THALLIUM;SURFACE;INDIUM