Cyclic voltammetry studies of copper and nickel hexacyanoferrate immobilized on a silica gel surface coated with titanium(IV) oxide

Abstract

The cyclic voltammetric behavior of copper and nickel hexacyanoferrate complexes immobilized on a silica gel surface coated with Ti(IV) oxide indicated good chemical stability for the copper complex film and that the nickel film undergoes a structural change with time. The potential of the redox reaction Ti +{M[Fe III(CN) 6]} − + C + e − → Ti +{CM[Fe II(CN) 6]} − (M = Cu 2+, Ni 2+; C = K +, NH 4 +, Na +, Li +; Ti denotes Ti(IV) oxide substrate on a silica gel surface) is dependent on the degree of reticulation and the affinity of C to the transition metal hexacyanoferrate solid film. The cyclic voltammetry waves in Li + and Na + as the supporting electrolyte were broadened for Ti{Cu[Fe II/III(CN) 6]}, suggesting that the diffusion of these cations through the zeolitic cavity of the surface complex was hindered because of their larger hydrated ionic radii compared with those of K + and NH 4 +. The Ti{Ni[Fe II/III(CN) 6]} cyclic voltammetry waves depend on the capacity of the electroactive species on the Ti(IV) oxide surface to interact with the cationic species of the supporting electrolyte.