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

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 similar to 237.1 mu A cm(-2) mu M-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 (similar to 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 Xray absorption fine structure spectra.