Increasing charge transfer of SERS by the combination of amorphous Al₂O₃–Al thin film and ZnO nanorods decorated with Ag nanoparticles for trace detection of metronidazole

Abstract

In this work, we study the charge transfer improvement by the combination of two semiconductors of SERS.

Optimizing the Structure of Zinc Oxide Thin Films and Silver Nanoparticles for Preparing High-Performance and Stability SERS Substrate to Detect Banned Antibiotics in Aquaculture

“…In addition, the intensity of the intrinsic defects at the 568 cm –1 peak tends to increase slightly from 30 to 150 min. Thus, at the annealing time of 120 min, the ZnO thin film has both good crystallinity, high surface disorder, and high intrinsic defect, which play a significant role in enhancing the Raman signal by the charge transfer between the organic molecules and the SERS substrate. ,,, …”

“…The Ag/ZnO NPs SERS substrates are very stable over time and have good spectral reproducibility when used for MNZ detection. The Raman spectrum of MNZ powder measured by ref shows the characteristic Raman peaks at 730, 822, 869, 905, 983, 1183, 1264, 1350, 1372, 1481, and 1530 cm –1 , which are due to the CH 2 rocking, ring breathing, CH 3 rocking, CH 2 out of plane bending, O–H bending, C–H out of a plane, C–N stretching, C–C or CH 2 stretching, C–N stretching (aromatic), CH 2 scissoring, and CC vibration, respectively. , The solvent used to prepare the MNZ solution is MeOH. Figure a shows that the Ag/ZnO SERS substrates detect the Raman signal of MNZ solution at 10 4 ppm with characteristic Raman peaks similar to most of the MNZ powder peaks, while no signal of MeOH absorbed on the SERS substrate is recorded.…”

“…This is a prerequisite for strongly absorbing the incident light by metallic NPs. − Another reason is the “hot spot” effect which occurs at the tips and corners on the rough surface of noble metal nanostructures. The distance between these noble metal NPs is less than 10 nm . In these spots, due to the polarization of the NPs resulting from the incident light, the electric field can be dramatically increased .…”

“…In addition to this example, Barveen et al made a SERS-active substrate for the ultrasensitive detection of a popular antibiotic, chloramphenicol (CAP) by fabricating the heterogeneous integration of silver nanoparticles (Ag NPs) on silver vanadate nanorods (β-AgVO 3 NRs) . In addition, many studies indicate that the combination of noble metals and semiconductor nanostructures will enhance the SERS signal. ,− That is because, first, the semiconductor is easy to control the surface morphology where the metal NPs are attached to make good “hot spots”, thereby increasing the signal by the EM. Second, it supports the charge-transfer process between organic molecules and the substrate of the SERS substrate by the CE.…”

“…Additionally, it has biocompatibility and high chemical stability and is also reasonably in price. The morphology of ZnO nanomaterials could be easily controlled for nanorods, , nanobelts, nanowires, nanosheets, nanoneedles, and nanotubes . These structures with a high effective surface area combined with noble metal NPs will increase the electric field in SERS.…”