CN105621486A

CN105621486A - SERS (surface enhanced raman scattering) substrate based on plasma semiconductor molybdenum oxide and preparing method thereof

Info

Publication number: CN105621486A
Application number: CN201511000566.5A
Authority: CN
Inventors: 王灵芝; 张金龙; 谭贤军
Original assignee: East China University of Science and Technology
Current assignee: East China University of Science and Technology
Priority date: 2015-12-28
Filing date: 2015-12-28
Publication date: 2016-06-01

Abstract

The invention discloses a method for preparing an SERS (surface enhanced raman scattering) active substrate made of a novel molybdenum oxide semiconductor material with plasma characters. Firstly, molybdenum oxide nano slices with different plasma strengths and frequencies are prepared through a simple solvothermal method, and defect-state species (Mo5+, oxygen vacancy) on the surface are removed through mild calcination treatment. A series of representation prove that a MoO3-x@MoO3 nano slice with a core-shell structure is formed after the calcination treatment and shows extraordinary high-sensitivity activity when applied to SERS detection, the detection limit can reach 10-7 M, and the nano slice can be compared favorably with a precious metal nano structure. The prepared SERS substrate is good in repetition and high in sensitivity.

Description

A kind of SERS substrate based on plasma semiconductor oxide molybdenum and its preparation method

Technical field

The invention belongs to the technical field of advanced nano material and spectroscopy, it is specifically related to a kind of SERS active-substrate based on plasma semiconductor oxide molybdenum and its preparation method.

Background technology

In the last few years, precious metal was paid close attention to and research widely as gold and silver, copper etc. obtain because it has very strong local plasmon resonance characteristic. Owing to plasma resonance can change the interaction relevant with light, this makes precious metal at enhanced spectrum, and sensing, the aspect such as photochemical catalysis and optics has potential application. Recently, it has been found that the semi-conductor of some severe auto-dopings is such as TiO_2-x, Cu_2-xS, WO_3-xAnd Cu_2-xTe etc. also have the local plasmon resonance of similar metal, which results in the very big interest of researcher. But, the absorbing wavelength of the plasma semi-conductor of great majority report is near infrared and mid infrared region. Recently studies have reported that the plasma resonance of semi-conductor can be adjusted to the section wavelength region may (780-1100nm) of near infrared. These semiconductor materials with the plasma resonance frequency close with precious metal are expected to supplement and replace the application of precious metal at a series of optical field.

In surface enhanced Raman scattering (SERS) spectrum, noble metal nano structure has obtained deep research. Compared to precious metal material, adsorptive behavior and the interface information of detection molecules can be reflected in the semiconductor-based end, but failing owing to detection sensitivity is low to access pays close attention to widely. Having report to point out, by control synthesis condition, plasma semiconductor material can have the plasma resonance absorption similar with precious metal material, and show the adjustable LSPR depending on shape looks and absorb. The difference is that, precious metal has relatively fixing carrier concentration (~ 10²³m^-3), and the carrier concentration of plasma semi-conductor can according to doping content, the condition free such as temperature of reaction and phase in version regulates. But, so far, do not report about the relation between the essential characteristic (such as carrier concentration and distribution) of the electronic structure of plasma semi-conductor and SERS. In addition, plasma semi-conductor whether have with precious metal like SERS characteristic also do not studied. Therefore, in the mechanism and enhancement mechanism of SERS, sensitivity is still a very attractive problem with challenging to research plasma semiconductor application with improving.

Summary of the invention

The critical problem solved of the present invention is the SERS base that the method by simple and fast prepares high sensitivity, and deeply probes into and disclose the mechanism and enhancement mechanism of plasma semi-conductor in SERS detects.

The present invention provides a kind of SERS active-substrate based on plasma semiconductor oxide molybdenum and its preparation method, it is possible to be achieved through the following technical solutions:

Based on a SERS active-substrate for plasma semiconductor oxide molybdenum, it is the MoO possessing plasma resonance characteristic of a kind of nucleocapsid structure_3-xMoO₃Nanometer sheet, its length and width are about 80-200nm, and thickness is about 30nm. Owing to it belongs to the semiconductor material of severe auto-doping, therefore this nanometer sheet has stronger local plasmon resonance characteristic; Owing to surface may form the defective bit (Mo of catalytic active center⁵⁺, Lacking oxygen) it is removed, the impact of the detected molecule of photocatalytic degradation is greatly diminished; On the other hand, the plasma MoO of body phase_3-xKernel has very strong plasma resonance characteristic, can the electromagnetic field of inducing peripheral significantly strengthen, and then strengthens Raman scattering signal, it is possible to show very high SERS detection sensitivity.

Described nanometer sheet shows good repeatability as SERS substrate, and relative standard deviation can reach 8.6%;

Described nuclear shell structure nano sheet has very high detection sensitivity, and for methylene blue, limit of detection can reach 10^-7M, enhancement factor is 1.42 �� 10⁵��

The method specifically comprises the following steps:

(1) being dissolved in hydrogen peroxide by metal molybdenum powder when ice-water bath, magnetic force stirs 30min to remove excessive hydrogen peroxide, obtains molybdenum source precursor liquid;

(2) molybdenum source precursor liquid is joined in methanol solution, stir 30min and mix, proceed in the polytetrafluoroethyllining lining of 30mL, be sealed in high pressure water heating kettle, be placed in 170 degree of baking ovens and react 12h.

(3) to be cooled to room temperature, centrifugation, by methanol wash 3 times, is placed in the dry 8h of 60 degree of vacuum drying ovens, obtained MoO_3-xNanometer sheet;

(4) MoO that will prepare_3-xNanometer sheet is placed in 200 degree of retort furnaces, calcines 6h under air atmosphere, obtains the MoO of nucleocapsid structure_3-xMoO₃Nanometer sheet.

In described step (1), the concentration of molybdenum source precursor liquid is 1mol/L.

Methanol usage in described step (2) is 20mL.

Present aspect prepares plasma MoO by the method for simple solvent thermal_3-xNanometer sheet, then the MoO of nucleocapsid structure is obtained through gentle calcination processing_3-xMoO₃Nano material, the nanometer sheet prepared by the method is had the following advantages as SERS substrate:

(1) nuclear shell structure nano sheet has plasma resonance characteristic, can induce generation office territory electromagnetic field under illumination condition, strengthens Raman scattering signal;

(2) shell of the photochemical catalysis inertia of nuclear shell structure nano sheet can protect detected molecule in the photodegradation of induced with laser, reduces the interference even removing and degrading to SERS detection;

(3) there is very high detection sensitivity;

(4) described preparation method is simple to operate, good as SERS substrate repeatability.

Accompanying drawing explanation

Fig. 1 is the MoO of preparation_3-x-170^oThe SEM photograph of C nano sheet;

Fig. 2 is the MoO of preparation_3-x-170^oThe TEM photo of C nano sheet;

Fig. 3 is the MoO of preparation_3-x-170^oThe XRD spectra of C nano sheet;

MoO prepared by Fig. 4_3-x-170^oThe Raman photo of C nano sheet;

Fig. 5 is the MoO of preparation_3-x-170^oC, MoO3-x-180^oC nano sheet and business MoO₃UV-vis-NIRDRS spectrogram;

Fig. 6 is MoO_3-xMoO₃The Raman spectrum figure of detection different concns MB.

Embodiment

Below in conjunction with the drawings and specific embodiments, the present invention is described in detail.

The present invention provides a kind of SERS active-substrate based on plasma semiconductor oxide molybdenum and its preparation method, and concrete steps are as follows:

The first step, is dissolved in hydrogen peroxide by metal molybdenum powder when ice-water bath, and magnetic force stirs 30min to remove excessive hydrogen peroxide, obtains molybdenum source precursor liquid;

2nd step, joins in methanol solution by molybdenum source precursor liquid, stirs 30min and mixes, proceeds in the polytetrafluoroethyllining lining of 30mL, be sealed in high pressure water heating kettle, be placed in 170 degree of baking ovens and react 12h.

3rd step, to be cooled to room temperature, centrifugation, by methanol wash 3 times, is placed in the dry 8h of 60 degree of vacuum drying ovens, obtained MoO_3-xNanometer sheet, at this temperature, the molybdenum oxide nanometer sheet of preparation is designated as MoO_3-x-170^oC.

4th step, the MoO that will prepare_3-xNanometer sheet is placed in 200 degree of retort furnaces, calcines 6h under air atmosphere, obtains the MoO of nucleocapsid structure_3-xMoO₃Nanometer sheet.

The SERS substrate that above-mentioned preparation method obtains is that length and width are about 80-200nm, and thickness is about the nanometer sheet of 30nm, through the MoO of the nucleocapsid structure that calcination processing is formed_3-xMoO₃There is very high sensitivity.

Claims

1. the SERS active-substrate based on plasma semiconductor oxide molybdenum and its preparation method, it is characterised in that, first the method prepares the MoO and having different plasma resonance frequency by the method for simple solvent thermal_3-xNanometer sheet, and then the defect state species on surface are removed by the calcination processing of gentleness, form the MoO of nucleocapsid structure_3-xMoO₃Nanometer sheet.

2. the nanometer sheet described in possesses characteristics of plasma as SERS substrate because of kernel and the shell of photochemical catalysis inertia turn avoid the impact of degraded, so showing very high sensitivity in detection probes molecule methylene blue.

3. specifically comprise the following steps:

The first step, is dissolved in hydrogen peroxide by metal molybdenum powder when ice-water bath, and magnetic agitation is about 30min, removes excessive hydrogen peroxide, obtained molybdenum source precursor liquid;

2nd step, is proceeded in filling in the tetrafluoroethylene containing a certain amount of methyl alcohol, is sealed in stainless steel autoclave, is placed in 170 degree of baking ovens and reacts 12h; To be cooled to room temperature, by sample centrifugation, by washed with methanol 3 times, in 60 degree of vacuum drying ovens, dry 8h, prepares MoO_3-xNanometer sheet;

3rd step, gets a certain amount of MoO_3-xNanometer sheet, under air atmosphere, is placed in retort furnace and calcines 6h under 200 degree, obtain the MoO of nucleocapsid structure_3-xMoO₃Nanometer sheet.

4. according to claim 1 always based on SERS active-substrate and its preparation method of plasma semiconductor oxide molybdenum, it is characterised in that, in the 2nd step, methyl alcohol is not only as solvent but also as reductive agent, it is possible to by Mo⁶⁺Species are reduced to Mo⁵⁺, form Lacking oxygen simultaneously.

5. preparation method according to claim 1, it is characterised in that, in the 2nd step, simply by adjustment temperature of reaction, the molybdenum oxide nanometer sheet and there is different plasma resonance frequency can be prepared;

Preparation method according to claim 1, it is characterised in that, in the third step, the condition forming nuclear shell structure nano sheet at the temperature of gentleness, need to have in the atmosphere of oxygen and could be removed in the defect state site on surface;

Preparation method according to claim 1, it is characterised in that, described nucleocapsid structure molybdenum oxide nanometer sheet length and width are about 80-200nm, and thickness is about 30nm.