Self-assembly of silver nanoparticles as high active surface-enhanced Raman scattering substrate for rapid and trace analysis of uranyl(VI) ions

Rapid and sensitive detection of uranyl ion with citrate-stabilized silver nanoparticles by the surface-enhanced Raman scattering technique

“…The SERS band of uranyl is lower (750 cm −1 ) than uranyl citrate Raman band (832 cm −1 ) (see electronic supplementary material, figure S3), indicating strong coordination between uranyl and silver along with Cit. The strong chemical interactions between uranyl ion and ligands weaken the axial U=O band intensity due to the extensive electron density transfer from citrate and silver surface to the equatorial plane of absorbed uranyl ions, causing the uranyl band to shift from 870 cm −1 to a lower wavenumber, which has been reported in the previous literature [33–35]. Sample C obtains a good SERS signal of uranyl (figure 1 d ).…”

The contribution of photoinduced charge-transfer enhancement to the SERS of uranyl(VI) in a uranyl-Ag2O complex

“…Due to its fast response, high sensitivity, and its successful application in the rapid trace analysis of biological molecules [15][16][17], organic pollutants [18][19][20][21][22], and heavy metal ions [23,24], SERS is expected to become an alternative technique for the detection of uranyl. Currently, many studies have reported the SERS of uranyl ions, and the employed SERS substrates are mainly based on Ag nanostructures, such as Ag nanorods arrays [25,26], Ag nanoparticles [27][28][29], Ag-doped sol-gel film [30], etc. These Ag nanostructures have been shown to produce significant Raman enhancements from the uranyl ions located close to their surfaces, which contributes to the trace analysis of uranyl ions.…”

“…Hence, a substitute that only produces a CT enhancement is needed. Herein, Ag 2 O was used as the substitute for Ag substrates for the following reasons: (1) the CT enhancement is independent of the geometric configuration of the Ag substrate but is related to the chemical reaction that it undergoes with uranyl; (2) the equatorial plane of uranyl coordinates with Ag 2 O via an oxo-bridge geometry, namely U-O-Ag, which was also observed for the uranyl ions adsorbed on the Ag substrates [27,28]; (3) since it is a p-type semiconductor, the surface plasma resonance frequency of Ag 2 O lies in the infrared region, far from 532/638/785 nm excitation lines used in this research, which should effectively exclude the EM enhancement from the Ag 2 O substrate. Therefore, to deeply understand the CT enhancement on the Ag substrate, the photoinduced CT process in a uranyl-Ag 2 O complex was thoroughly discussed using experimental and theoretical results to offer explanations.…”

In Situ Surface-Enhanced Raman Spectroscopy Detection of Uranyl Ions with Silver Nanorod-Decorated Tape

“…The very large shift of the uranyl peak can be explained by the strong charge transfer from the silver to the equatorial plane of the absorbed UO 2 2+ , weakening the axial U=O bond intensity, which were also reported in the literature. 16,19,25,29 The broad SERS peak of UO 2 2+ with uncertain peak values implies that the interaction between UO 2 2+ and silver is complicated, and there may be several hydrolyzed uranyl complexes absorbed on the silver surface, several interaction modes between them, or both simultaneously. The charge transfer mechanism between them needs further study.…”