An insight into the electrochemical behavior of Co/Al layered double hydroxide thin films prepared by electrodeposition

• Published in: Journal of power sources 2012-03, Vol.201, p.360-367
• Main Authors: Scavetta, Erika, Ballarin, Barbara, Corticelli, Claudio, Gualandi, Isacco, Tonelli, Domenica, Prevot, Vanessa, Forano, Claude, Mousty, Christine
• Format: Article
• Language: English
• Subjects: Applied sciences; Co/Al layered double hydroxide; Coated electrode; Electrical engineering. Electrical power engineering; Electrodeposition; Electrooxidation; Exact sciences and technology; Materials
• ISSN: 0378-7753; 1873-2755
• DOI: 10.1016/j.jpowsour.2011.10.122

► Co layered double hydroxide thin films are prepared by electrodeposition. ► Electrochemical oxidation in alkaline solution lead to an irreversible phase transition. ► The resulting γ-Co(III)OOH like phase is highly stable under cycling. ► It shows a pseudo-capacitive behavior with a specific capacitance of 500 F g −1. A detailed study aimed at clarifying the electrochemical behavior of Co/Al-LDH thin films, prepared on Pt electrode by electrodeposition at −0.9 V, has been carried out. Reproducible thin and homogeneous films with variable amounts of LDH coated on the electrode surface have been achieved by varying the electrodeposition time ( t = 5, 10, 30 and 60 s): 29.2 ± 0.7, 37.9 ± 1.4, 55.1 ± 2.1 and 62.5 ± 4.3 μg cm −2, respectively. X-ray diffraction, spectroscopic techniques and the electrochemical quartz crystal microbalance analysis have been used to give an insight into the phase changes occurring when the as-prepared Co/Al-LDH thin films were oxidized and reduced by cycling the potential between 0 and 0.6 V/SCE in 0.1 M KOH. Our experiments demonstrate that the irreversible oxidation peak observed in the first cycle corresponds to the transformation of the Co(II)/Al-LDH phase in a γ-Co(III)OOH like phase. This resulting phase is stable under cycling and shows a pseudo-capacitive behavior with an estimated specific capacitance of 500 F g −1.