Abstract
The iron complex hexacyanoferrate (Fe4[Fe(CN)6]3), known as Prussian Blue (PB), was electrodeposited over a free-standing carbon nanotube (CNT) film assembled at the interface between two immiscible liquids, water and 1,2-dichlorobenzene. Polarization of the interface achieved through a fixed potential or under potential variation enabled iron present inside CNTs to generate a stable CNT/PB composite. We report herein on the observation that the deposition of PB is dependent on both the pH and applied potential. It was found that aqueous phases containing K3[Fe(CN)6] can decompose under an applied potential, while those containing K4[Fe(CN)6] presented more stable behavior making it a suitable precursor for PB synthesis. The electrodeposition and modification of the interface was followed by in situ spectroelectrochemical Raman spectroscopy, which indicated that an increase in signal due to PB formation was acompanied by changes in the CNT bands due to modification of the CNT walls by decoration with PB, forming a composite structure.
Highlights
Biphasic liquid/liquid (L/L) systems have been used for a long time, either for the study of interfacial electron and ion transfer reactions or for the synthesis and assembly of micro and nano-sized materials.[1,2] The interface between two immiscible liquids provides a defect-free environment suitable for controlled homogeneous particle deposition
In order to form Prussian Blue (PB), the metal species must first be extracted from the carbon nanotube (CNT) so that they can react with the other precursor, potassium hexacyanoferrate, in the aqueous solution, as follows: K+ + Fe2+ + [Fe(CN)6]3– → KFe[Fe(CN)6]
The appearance and growth of the redox process associated with the transition between PB and its oxidized form, Berlin Green (BG), at Dj1/2 ca. 0.74 V is a characteristic sign of PB electrodeposition over the film
Summary
Biphasic liquid/liquid (L/L) systems have been used for a long time, either for the study of interfacial electron and ion transfer reactions or for the synthesis and assembly of micro and nano-sized materials.[1,2] The interface between two immiscible liquids provides a defect-free environment suitable for controlled homogeneous particle deposition. Voltammetric responses similar to peaks II and III due to lithium intercalation in CNTs, which could occur due to Li+ transfer from aqueous to organic phases at positive polarizations,[56] have been described, the experiments conducted in this work cannot confirm this effect.
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