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High Electrochemical Sensitivity of TiO2–x Nanosheets and an Electron-Induced Mutual Interference Effect toward Heavy Metal Ions Demonstrated Using X-ray Absorption Fine Structure Spectra

Zhou, Wen-Yi, Li, Shan-Shan, Song, Jie-Yao, Jiang, Min, Jiang, Tian-Jia, Liu, Jin-Yun, Liu, Jin-Huai, Huang, Xing-Jiu
Analytical chemistry 2018 v.90 no.7 pp. 4328-4337
Raman spectroscopy, X-ray absorption spectroscopy, X-ray photoelectron spectroscopy, cadmium, copper, electrochemistry, electron paramagnetic resonance spectroscopy, heavy metals, metal ions, nanosheets, oxygen, titanium dioxide
Mutual interference is a severe issue that occurs during the electrochemical detection of heavy metal ions. This limitation presents a notable drawback for its high sensitivity to specific targets. Here, we present a high electrochemical sensitivity of ∼237.1 μA cm–² μM–¹ toward copper(II) [Cu(II)] based on oxygen-deficient titanium dioxide (TiO₂–ₓ) nanosheets. We fully demonstrated an atomic-level relationship between electrochemical behaviors and the key factors, including the high-energy (001) facet percentage, oxygen vacancy concentration, surface −OH content, and charge carrier density, is fully demonstrated. These four factors were quantified using Raman, electron spin resonance, X-ray photoelectron spectroscopy spectra, and Mott–Schottky plots. In the mutual interference investigation, we selected cadmium(II) [Cd(II)] as the target ion because of the significant difference in its stripping potential (∼700 mV). The results show that the Cd(II) can enhance the sensitivity of TiO₂–ₓ nanosheets toward Cu(II), exhibiting an electron-induced mutual interference effect, as demonstrated by X-ray absorption fine structure spectra.