Iron compounds electrodeposited onto a transparent semiconductor: Synthesis and characterisation by UV–vis spectroscopy

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• 作者：Sophie Peulon ; Quentin Baraize ; Annie Chaussé
• 关键词：Lepidocrocite ; Layered Fe(II)– ; Fe(III) hydroxi-salts ; Mixed-valence minerals of iron ; Intervalence-transfer ; Isobestic point
• 刊名：Electrochimica Acta
• 出版年：2007
• 期刊代码：30_00134686
• 类别：ch
• 出版时间：10 October 2007
• 卷：52
• 期：27
• 页码：7681-7688
• 文件大小：952 K

摘要

Homogeneous thin layers of lepidocrocite, green rust incorporating chloride anions (GRCl–GR1) and green rust incorporating sulphate anions (GRSO₄–GR2) were successfully electrodeposited onto tin dioxide substrate (SnO₂). The UV–vis spectroscopy absorbance, measured just after synthesis, increases linearly with the amount of iron compounds confirming that the electrodeposition is a homogeneous process. From the spectra, the absorption coefficients were determined for the three compounds. The monitoring by UV–vis spectroscopy measurements in real time of the oxidation in the air of the two unstable compounds, GRCl and GRSO₄, shows that the two green rusts have a different behaviour due to their own structure. The presence of an isobestic point in the case of GRSO₄ translates one equilibrium with its oxidised compound. This phenomenon is not observed for GRCl, however, the characteristic variation of the absorbance in the high wavelengths gives information on its oxidation reaction. From simple measurements, fruitful information on green rusts is obtained and this experimental system may be applied to other unstable solid compounds.