Abstract
A photoelectrochemical (PEC) method based on the etching reaction of F ions on the surface of TiO2 nanorod arrays (TNRs) was proposed for the high sensitivity and selectivity detection of F ions. With the increase of F ion concentration, the surface etching reaction on TNR becomes more intense, resulting in the increased number of surface active sites, the reduction of electron transfer resistance, and the increase of photocurrent density. The prepared TNRs as a PEC probe exhibits a good linear relationship between photocurrent increment and the logarithm of F ion concentration in the range from 0.05 to 1000 nM with an ultra-trace detection limit of 0.03 nM for F ion detection.
Highlights
The uorine ion (F ion), as the smallest anion among the anions,[1] has gained signi cant attention due to its important role in health and environmental issues, such as dental health,[2] orthodontic appliances,[3] osteoporosis[4] and pharmaceutical agents.[5]
Comparing the highresolution X-ray photoelectron spectroscopy (XPS) pattern of F 1s before and a er immersing in F ion solution, a small peak of F on the surface of TiO2 at 684.3 eV is observed.[35]. These results indicate that a small part of F may dope into TiO2 nanorod arrays (TNRs)-5, which increases the photocurrent by promoting the separation of photogenerated electrons and holes
The absorption in the visible-light region has no signi cant change, revealing the F was not doped into the TiO2.36 From the EIS Nyquist plots, it can be seen that the arc radius of the used TNRs-5 a er detecting F ion is obviously smaller than that of the original TNRs-5, and the calculated value of Rct for the both samples is 248.8 U cmÀ2 and 223.8 U cmÀ2, respectively (Fig. 8D), indicating the enhance of charge transfer efficiency
Summary
The uorine ion (F ion), as the smallest anion among the anions,[1] has gained signi cant attention due to its important role in health and environmental issues, such as dental health,[2] orthodontic appliances,[3] osteoporosis[4] and pharmaceutical agents.[5]. Some sensing systems are inappropriate for wide application due to instability of detection,[9] expensive instruments,[10] complex sample handling,[11] or speci c detection conditions.[12] It is of great interest and importance to look for a simple and effective material and method for highly sensitive and selective detection of F ions. For PEC detection of F ion, the photocurrents of TNRs were measured before and a er immersion in the NaAc–HAc buffer solution with different concentrations of NaF solution
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