Influence of copper anion complexes on the incorporation of metal particles in polyaniline - Part II: Copper oxalate complex

Copper deposition at polyaniline (PAN) coated electrodes is studied using copper oxalate complexes as reducing species. It is found that a high number (3.4 x 10(8) cm(-2)) of single sized (150 nm), regular shaped crystals can be obtained. Statistical analysis of the distances between neighbouring crystals shows deviation from a random surface distribution. This finding is discussed both in terms of origin and overlap of nucleation exclusion zones and of the influence of the finite size of the copper crystals. Experiments performed under potentiostatic conditions give evidence for instantaneous copper nucleation and growth under phase boundary transition limitations. Results concerning number, size and shape of copper crystals deposited in a similar way using three different reducing species (i.e., copper cations, copper citrate and copper oxalate complex anions) are compared. It is established that the copper oxalate complex anions allow for deposition of the largest number of small metal crystals. This result is related to both the initial oxidation state of the PAN layer in the oxalate solution and to the specific properties of the anion complex.