In situ controlled sputtering deposition of gold nanoparticles on MnO₂ nanorods as surface-enhanced Raman scattering substrates for molecular detection

Abstract

Single-crystal tetragonal α-MnO2 nanorods with different amounts of gold nanoparticles (NPs) attached were successfully prepared by a facile sputtering deposition technique. Initially, the morphology and crystal structure of the bare α-MnO2 nanorods synthesized via a hydrothermal approach were investigated. Then, the amount of gold NPs at different sputtering times was analyzed. It was confirmed that the amount of the decorated gold NPs increased with the lengthening of the sputtering time until they completely covered the α-MnO2 nanorods. Theoretical calculation results indicated the advantages of the composite structure by showing the enhanced electromagnetic fields around both the bare α-MnO2 nanorods and the gold NP decorated ones. The surface-enhanced Raman scattering (SERS) efficiency of these nanocomposites was evaluated using methylene blue and 4-mercaptobenzoic acid as Raman probe molecules. It was found that the SERS intensity of the substrates strongly depended on the degree of aggregation of the gold NPs. Uniform SERS signals across the entire surface of these samples were obtained. Moreover, a typical chemical toxin, methyl parathion, was effectively detected over a broad concentration range from 1 × 10(-3) to 100 ppm using the gold NP decorated α-MnO2 nanorods, suggesting this hybrid structure is highly valuable for further applications on the rapid detection of organic environmental pollutants.

Hydrothermal synthesis of gold polyhedral nanocrystals by varying surfactant concentration and their LSPR and SERS properties

“…[1][2][3][4][5][6] Especially, the localized surface plasmon resonance (LSPR) property is one of the current prevalent issues, owing to the intriguing optical characteristics arising from the collective oscillation of electrons in the conduction band of metals upon laser irradiation which leads to electromagnetic eld enhancement of several orders of magnitude. 3,7,8 As the most famous practical consequence of the plasmonic coupling effect, 9 the surface enhanced Raman scattering (SERS) technology has been implemented in ultra-sensitive detection, [10][11][12][13] because it can amplify the spectroscopic signatures and offer structural information of target molecules adsorbed on the surface of metal nanostructures. 14,15 As is well known, the LSPR of noble metal NCs exhibits a strong dependence on their size, shape and chemical composition.…”

Molybdenum sulfide–reduced graphene oxide p–n heterojunction nanosheets with anchored oxygen generating manganese dioxide nanoparticles for enhanced photodynamic therapy

“…The successful conversion of GO to rGO by thiourea is evident from the shift of the (002) reflection from 2 θ = 10° to 24.6°, respectively 23. In p-MoS 2 /n-rGO–MnO 2 –PEG, MnO 2 can be distinguished from MoS 2 by its distinct (310) reflection at 2 θ = 29° 24. Similarly in the Raman spectra, the 640 cm –1 vibrational band of MnO 2 is prominent within the characteristic bands of MoS 2 at 377 and 403 cm –1 for in-plane E 1g and out-of-plane A 1g vibration modes, respectively 25.…”

Plasmon-coupled Charge Transfer in FSZA Core-shell Microspheres with High SERS Activity and Pesticide Detection

“…The two dominant peaks at 1079 and 1587 cm −1 are assigned to the ring-breathing modes. The Raman band at 839 cm −1 is attributed to the COO − bending mode (δ(COO - )) and that at 1140 cm −1 is attributed to a mixed mode (13β(CCC) + ʋ(C–S) + ʋ(C–COOH)) 20 . In addition, the band at approximately 1183 cm −1 is mainly due to the a 1 vibration of v (CH), the band centered at 1364 cm −1 is due to the symmetric stretch of the carboxylate group ν(COO − ).…”