Charge-Selective Raman Scattering and Fluorescence Quenching by “Nanometal On Semiconductor” Substrates

Bhatt, Karthik; Tan, Susheng; Karumuri, Sriharsha; Kalkan, A. Kaan

doi:10.1021/nl101480n

Cited by 35 publications

(22 citation statements)

References 74 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Figure a and b shows the topographical image of wet ferrite pellet in a 1 µm 2 scanning area. The tip of the cantilever has been biased by applying dc voltages –0.6 and +0.6 V lower than the water dissociation voltage of 1.23 V. The change in frequency of cantilevers as a result of influence of electric field gradient generated by electrostatic surface charge has been observed as shown in Figure c and d. It has been observed by electrostatic force microscopy image that the polarity of dc bias could invert the image contrast, revealing attractive and repulsive force . On applying −0.6 V, bias on tip bright contrast demonstrated attractive force as a result of hydronium ions' presence in physisorbed water molecules.…”

Section: Resultsmentioning

confidence: 96%

Green hydroelectrical energy source based on water dissociation by nanoporous ferrite

Kotnala

Shah

2016

Int. J. Energy Res.

109

View full text Add to dashboard Cite

Summary Dissociation of water molecule occurs on octahedrally coordinated unsaturated suface cations and oxygen vacancies created by lithium substitution in magnesium ferrite. Lower synthesis temperature of ferrite has generated nanopores in microstructure. Dissociated hydronium and hydroxyl ions are transported through surface and capillary diffusion in porous ferrite network towards attached Zn and Ag electrodes. Water molecule dissociation ability of nanoporous ferrite has been exploited to develop a green electrical energy cell, which is a combination of material science and electrode chemistry. The innovated cell has been nomenclatured as hydroelectric cell (HEC). When HEC is partially dipped in deionized water, spontaneously hydroxide and hydronium ions are produced by water molecule dissociation. Hydronium ions trapped in nanopores develop enough electric field that further dissociates physisorbed water molecules. Thereby, the process of water molecule dissociation is accelerated in a bigger way to increase ionic current in the cell. Oxidation of Zn electrode by hydroxide ion and reduction of H3O+ at Ag electrode develop voltage and electric current in the cell. The HEC cell of a 17 cm2 area is able to generate a short circuit current of 82 mA and 920 mV emf with a maximum output power of 74 mW, which is three order higher than reported output power 1.4 μW/cm2 produced by water in cement matrix. Hydroelectric cell performance is repetitive, stable and possesses potential to replace traditional ways of generating renewable energy in terms of cost and safety. Copyright © 2016 John Wiley & Sons, Ltd.

show abstract

Section: Resultsmentioning

confidence: 96%

Green hydroelectrical energy source based on water dissociation by nanoporous ferrite

Kotnala

Shah

2016

Int. J. Energy Res.

109

View full text Add to dashboard Cite

show abstract

“…As a consequence of the charge redistribution, Ag is positively charged, while ZnO is negatively charged, and the highest charge‐density region is located on the adjacent face of Ag‐NPs and ZnO‐NRs. This local electric field can enhance the localized electromagnetic field excited by the surface plasmon resonance to improve the Raman scattering of the analytes 26, 45, 46. To further prove the supporting chemical enhancement effect of the ZnO‐NRs, we compared the Raman activities of three substrates: an Ag film growing on a ZnO film (ZnO/Ag film), a bare ZnO film, and a bare Ag film.…”

Section: Resultsmentioning

confidence: 99%

Arrays of Cone‐Shaped ZnO Nanorods Decorated with Ag Nanoparticles as 3D Surface‐Enhanced Raman Scattering Substrates for Rapid Detection of Trace Polychlorinated Biphenyls

Tang

Meng

Huang

et al. 2011

Adv Funct Materials

319

220

View full text Add to dashboard Cite

have been presented. [5][6][7] For many years SERS substrates were primarily restricted to noble metal (Au, Ag, and Cu) structures. Recently, it has been found that various semiconductors, such as ZnO, [8] ZnS, [9] TiO 2 , [10] Cu 2 O, [11] and CuO, [12] can also generate weak SERS activity with typical prominent enhancement factors ranging from 10 1 to 10 3 . Therefore, composites or heterostructures between semiconductors (Si, ZnO, and TiO 2 ) and noble metals (Au and Ag) have attracted attention, as a much higher SERS effect could be achieved due to the contributions from both the electromagnetic enhancement (excited by the localized surface plasmon resonance of noble metals) and the semiconductor supporting chemical enhancement (caused by the charge transfer between the noble metal and the adjacent semiconductor). [13][14][15][16][17][18][19][20] ZnO, a versatile semiconductor material with a direct band gap of 3.37 eV, has received special attention due to its excellent performance in supporting chemical enhancement of SERS substrates. [21,22] Several methods have thus been developed to fabricate this new type of ZnO/noble metal hybrid SERS substrate. For example, electroless plating was employed to assemble Ag nanoparticles (Ag-NPs) onto the surface of ZnO nanorods (ZnO-NRs) by sensitizing and activating with Sn 2+ or by irradiation with UV light. [22,23] Interestingly, the Ag-NPs could also be located on the tips of the ZnO-NRs via a photodeposition method or galvanic reduction. [24,25] Alternatively, with the help of surface modification with amino or mercapto groups, Au-NP/ZnO-particle and Au-or Ag-NPs/ZnO-multipods hybrid structures were achieved. [21,26] However, the spatial gaps between these small noble metal particles on the ZnO supporter were too large to work efficiently as SERS "hot spots" and, moreover, the complicated coupling agents for linking the metal NPs onto the ZnO surface, such as (3-aminopropyl) triethoxysilane, may bring extra interferential bands in the SERS measurements, especially if the target analytes have similar Raman spectral response with the coupling agents. To tackle this problem, physical sputtering was exploited. For example, a SERS substrate called "3D hybrid Ag-nanocluster-decorated ZnO nanowire arrays" was fabricated Arrays of Cone-Shaped ZnO Nanorods Decorated with Ag Nanoparticles as 3D Surface-Enhanced Raman Scattering Substrates for Rapid Detection of Trace Polychlorinated BiphenylsA new, highly sensitive and uniform three-dimensional (3D) hybrid surfaceenhanced Raman scattering (SERS) substrate has been achieved via simultaneously assembling small Ag nanoparticles (Ag-NPs) and large Ag spheres onto the side surface and the top ends of large-scale vertically aligned coneshaped ZnO nanorods (ZnO-NRs), respectively. This 3D hybrid substrate manifests high SERS sensitivity to rhodamine and a detection limit as low as 10 −11 m to polychlorinated biphenyl (PCB) 77-a kind of persistent organic pollutants as global environmental hazard. Three kinds of inter-Ag-NP gaps in ...

show abstract

“…The Fermi level of zinc oxide in the composite material is higher, and the Fermi level of silver is lower. As a consequence of charge redistribution, the SERS activity of the FSZA substrates are higher than that of the FSZ substrates, indicating that the charge transfer from Ag to ZnO leads to the formation of an inter electric field 29,30 . As shown in Fig.…”

Section: Resultsmentioning

confidence: 99%

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

Han

Yao

Quan

et al. 2019

Sci Rep

View full text Add to dashboard Cite

A commercial SERS substrate does not only require strong enhancement, but also can be reused and recycled in actual application. Herein, Fe3O4/SiO2/ZnO/Ag (FSZA) have been synthesised, which consisted of Fe3O4 core with strong magnetic field response and an intermediate SiO2 layer as an electronic barrier to keep the stability of magnetite particles and outer ZnO and Ag as the effective layers for detecting pollutants. The SERS enhancement factor (EF) of the FSZA was ~8.2 × 105. The enhancement mechanism of the FSZA core-shell microspheres were anatomized. The electromagnetic enhancement of surface deposited Ag, charge transfer, and molecular and exciton resonances act together to cause such high enhancement factors. For practical application, the FSZA core-shell microspheres were also used to detect thiram, moreover, which was collected and separated by an external magnetic field, and maintained the SERS activity without significant decline during multiple tests. So the good enhancement performance and magnetic recyclability make the FSZA core-shell microspheres a promising candidates for practical SERS detection applications.

show abstract

Charge-Selective Raman Scattering and Fluorescence Quenching by “Nanometal On Semiconductor” Substrates

Cited by 35 publications

References 74 publications

Green hydroelectrical energy source based on water dissociation by nanoporous ferrite

Green hydroelectrical energy source based on water dissociation by nanoporous ferrite

Arrays of Cone‐Shaped ZnO Nanorods Decorated with Ag Nanoparticles as 3D Surface‐Enhanced Raman Scattering Substrates for Rapid Detection of Trace Polychlorinated Biphenyls

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

Contact Info

Product

Resources

About