Iron Oxide with Different Crystal Phases (α- and γ-Fe2O3) in Electroanalysis and Ultrasensitive and Selective Detection of Lead(II): An Advancing Approach Using XPS and EXAFS

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• 作者：Shan-Shan Li ; Wen-Juan Li ; Tian-Jia Jiang ; Zhong-Gang Liu ; Xing Chen ; Huai-Ping Cong ; Jin-Huai Liu ; Yu-Ying Huang ; Li-Na Li ; Xing-Jiu Huang
• 刊名：Analytical Chemistry
• 出版年：2016
• 出版时间：January 5, 2016
• 年：2016
• 卷：88
• 期：1
• 页码：906-914
• 全文大小：546K
• ISSN：1520-6882

文摘

Iron oxide with different crystal phases (α- and γ-Fe₂O₃) has been applied to electrode coatings and been demonstrated to ultrasensitive and selective electrochemical sensing toward heavy metal ions (e.g., Pb(II)). A range of Pb(II) contents in micromoles (0.1 to 1.0 μM) at α-Fe₂O₃ nanoflowers with a sensitivity of 137.23 μA μM^–1 cm^–2 and nanomoles (from 0.1 to 1.0 nM) at γ-Fe₂O₃ nanoflowers with a sensitivity of 197.82 μA nM^–1 cm^–2 have been investigated. Furthermore, an extended X-ray absorption fine structure (EXAFS) technique was applied to characterize the difference of local structural environment of the adsorbed Pb(II) on the surface of α- and γ-Fe₂O₃. The results first showed that α- and γ-Fe₂O₃ had diverse interaction between Pb(II) and iron (hydro)oxides, which were consistent with the difference of electrochemical performance. Determining the responses of Cu(II) and Hg(II) as the most appropriate choice for comparison, the stripping voltammetric quantification of Pb(II) with high sensitivity and selectivity at γ-Fe₂O₃ nanoflower has been demonstrated. This work reveals that the stripping performances of a nanomodifier have to be directly connected with its intrinsic surface atom arrangement.