Electrodeposition of Adherent Films of Lithium Phthalocyanine on Platinum and Stainless Steel Substrates by Oxidation of Dilithium Phthalocyanine

• Published in: Journal of the Electrochemical Society 2005, Vol.152 (11), p.C756-C763
• Main Authors: Sakthivel, K., Munichandraiah, N., Scanlon, L. G.
• Format: Article
• Language: English
• ISSN: 0013-4651
• DOI: 10.1149/1.2050407

Films of lithium phthalocyanine (LiPc) on Pt and stainless steel (SS) substrates are deposited by electrochemical oxidation of dilithium phthalocyanine (Li2Pc) in dimethyl sulfoxide or acetone consisting of LiBF4 as the supporting electrolyte. Unlike the powdery deposits of LiPc obtained by using tetrabutyl ammonium perchlorate (TBAP) as the supporting electrolyte, the deposits are adherent to the substrates when LiBF4 is used as the supporting electrolyte. Chemical oxidation of Li2Pc by TBAP is shown to be detrimental for the formation of powdery electrodeposits of LiPc, whereas LiBF4 does not oxidize Li2Pc and therefore adherent films of LiPc are obtained by electro-oxidation. Furthermore, the kinetics of electro-oxidation of Li2Pc to LiPc is different in TBAP and LiBF4 solutions, as inferred from the nature of cyclic voltammograms and also the values of transfer coefficient. The oxidation of Li2Pc occurs at higher potentials on SS in relation to the reaction on Pt. Nevertheless, LiPc films are adherent on both substrates and their crystal structure corresponds to a-phase. The LiPc/Pt electrodes exhibit electrochemical activity, whereas LiPc/SS electrodes exhibit capacitive behavior. The texture of LiPc on both Pt and SS is found to be fiber-like.