Resumo

HERNANDEZ-PEREZ, T; HOLGUIN, S; RIVERA, M  e  MORENO, A. MICROSCOPÍA DE FUERZA ATÓMICA Y MICROSCOPIA ÓPTICA IN SITU UTILIZADAS PARA ESTUDIAR LA ELECTROQUÍMICA DE UN HETEROPOLYANION. Rev. LatinAm. Met. Mat. [online]. 2001, vol.21, n.2, pp.59-63. ISSN 0255-6952.

In this work, the electrochemical deposit of the [CoMo6O18(OH)6]^3- heteropolyanion (HPA) on a highly oriented pyrolytic graphite (HOPG) electrode is studied by in situ AFM and in situ optical microscopy (OM). The electrochemical behavior of this material indicates that the HPA reduction originates a deposit of the compound by showing voltammograms similar to those found on the growth of an organic conducting polymer. The studies in the electrochemical module of the NanoScope IIIa (AFM-EC) showed that after HPA reduction (0.6 to- 1.5 V Vs Ag), some material is deposited on the HOPG surface forming an irregular phase. Meanwhile, by in situ OM, it was observed that HPA changed from yellow to a "green-blue" color after electroreduction. This observation is the first one to be achieved for this HPA with an Anderson-Perlof structure. The thickness and shape of the new formed phase depended on both, the number of the potential scan cycles and the HPA concentration. Results showed that in situ AFM coupled to in situ OM are useful to demonstrate and to follow electrodeposition of films of inorganic compounds which form irregular phases and present real changes in color.

Palavras-chave : Heteropolianión; AFM in situ; microscopía óptica in situ.