CN104215625A

CN104215625A - Method for removing background signal of SERS (surface enhanced Raman spectrum) substrate manufactured by electrodeposition method

Info

Publication number: CN104215625A
Application number: CN201410477911.3A
Authority: CN
Inventors: 滕渊洁; 刘文涵
Original assignee: Zhejiang University of Technology ZJUT
Current assignee: Chongqing youlezi Technology Co.,Ltd.; Guangdong Gaohang Intellectual Property Operation Co ltd
Priority date: 2014-09-18
Filing date: 2014-09-18
Publication date: 2014-12-17
Anticipated expiration: 2034-09-18
Also published as: CN104215625B

Abstract

The invention provides a method for removing a background signal of an SERS (surface enhanced Raman spectrum) substrate manufactured by an electrodeposition method. The method comprises the following steps: increasing a Raman detection signal on the surface of a matrix by utilizing an electrodeposition reaction, and cleaning impurities remained on the surface. According to the invention, a nano metal electrode applied to the field of electro-catalysis is modified, so that the metal electrode has an SERS effect so as to be applied to the SERS field, and trace molecule detection is realized. In addition, from the angle of combining electrolyte and cleaning the surface sediments after electrodeposition, a complex with a higher stability constant than that of the sediments is selected and does not have interference or only has small interference, and the problem of Raman background interference in the SERS substrate prepared by the electrodeposition method is solved.

Description

The Raman spectrum base background signal minimizing technology that electrodeposition process makes

Technical field

The present invention relates to Raman spectrum detection field, especially belong to a kind of Surface enhanced raman spectroscopy (Electrochemical-Surface enhanced raman scattering, SERS) substrate background signal minimizing technology.

Background technology

Namely SERS effect utilizes laser and metallics to form excimer etc. from resonance effects, testing molecule is produced and increases about 10 ⁴-10 ⁶doubly even higher detection signal, has very large application prospect in the detection of trace molecules.So far, a lot of research is had to focus on the various substrate with SERS effect of exploitation, if any the roughened metal surface after utilizing redox reaction effect process and the substrate that utilizes electrochemical method to prepare; By the means such as physical vapor deposition, sputtering, metal nanoparticle is deposited on the substrate on the unlike material surfaces such as glass; The metal-sol of spherical, bar-shaped, nucleocapsid structure etc.; Monodispersed gold or silver nano-grain are self-assembled to by certain mode the MFON that inert substrate forms array; Photonic crystal substrate etc.Wherein, because electrodeposition process can make substrate surface form metal nanoparticle, nanometer sheet, nanometer rods etc. by controlling the condition such as electric current, voltage simply within a short period of time, method is easy, substrate is easy to get, now existing a lot of relevant report.But such electrode is used for greatly electro-catalysis field, and rarely has and be applied to Raman spectrum detection field, only having a small amount of relevant report, as utilized AgNO ₃with the silver-colored microsphere substrate that assemble nanometer sheet of citric acid as electrolytic solution, utilize Au (SO ₃) ₂ ^3-the star gold nano SERS substrate that electrolytic solution is obtained, utilizes HAuCl ₄and NaClO ₄as the gold nano grain plated film etc. of electrolytic solution.Wherein, main difficult point is when utilizing electrodeposition process to prepare SERS substrate, because SERS effect can make signal increase 10 ⁴above, the detection sensitivity of Raman signal is substantially increased.Therefore the impurity that surface concentrations is very low also can produce certain background interference, on the other hand, nano-metal particle can not be made exposed, also can reduce SERS effect if surface exists impurity.And the nano metal substrate in the electro-catalysis field that is applied to of existing report, only need to consider electric signal interference problem, and without the need to considering Raman background signal interference problem.Therefore miscellaneous nano metal substrate being applied to electro-catalysis field is applied in Raman detection, need the technical matters that solution one is crucial, namely detect to enable the substrate of preparation be applied to Raman spectrum, not the having or only have less background interference of substrate.

Summary of the invention

In order to overcome the above-mentioned defect of prior art, the invention provides a kind of method can removing SERS substrate Raman background signal.

The Raman spectrum base background signal minimizing technology that a kind of electrodeposition process provided by the invention makes, electrodeposit reaction is utilized to increase the Raman detection signal of matrix surface, and the impurity staying its surface is cleaned, comprise following steps: (1) selects the ionic species of less than three kinds to carry out electrodeposit reaction as electrolytic solution to conductive substrates, should select to disturb less ion pair to Raman background; (2) the substrate ultrapure water after electrodeposit reaction is cleaned; (3) clean the sediment remaining in substrate surface, the complex compound that Selection radio sediment stability constant is larger cleans, and complex compound itself should not have the matrix Raman back of the body or only have a small amount of interference; (4) again substrate ultrapure water is cleaned.

As preferably, in step (1), Ag is chosen as to the electrolytic solution that conductive substrates carries out electrodeposit reaction ₂sO ₄and H ₂sO ₄mixed liquor; Step is chosen as Na to the complex compound that sediment cleans in (3) ₂s ₂o ₃.Due to Ag ⁺and S ₂o ₃ ^2-the stability constant of complex compound is 10 ^14.15, stability constant is comparatively large, the Ag of formation ⁺and S ₂o ₃ ^2-complex compound can be dissolved in the water, and can not form solid.After cleaning, Nano Silver is exposed.Therefore with more stable and water-soluble Ag complex compound removing Ag ₂sO ₄method be feasible, can be used for processing the surface disturbance of the substrate obtained by this electro-deposition method.

As preferably, in step (1), select the Ag of 0.01mol/L ₂sO ₄with the H of 0.6mol/L ₂sO ₄with the mixed liquor of water as electrolytic solution, with the continuous current of 0.03A energising 30s, electrodeposit reaction is carried out to conducting base.

The present invention carries out modification to the nano metal electrode being applied to electro-catalysis field, makes it possess SERS effect, thus is applied to SERS field, realize the detection of trace molecules.On the other hand from the combination of electrolytic solution and the angle of electro-deposition rear surface sediment cleaning, select the complex compound larger than sediment stability constant, ensure that this complex compound itself does not have or only has very little interference, Raman background interference problem in SERS substrate prepared by solution electrodeposition process simultaneously.

Accompanying drawing explanation

Fig. 1 is after electro-deposition, without the substrate surface (a) of cleaning, with after KSCN rinsing (b), uses Na ₂s ₂o ₃the laser raman spectrogram of (c) after rinsing;

Fig. 2 is (A) and the scanning electron microscope (SEM) photograph cleaning rear (B) before cleaning.

Embodiment

The present embodiment is modified as example with porous silverskin.Under certain current density, 0.01mol/l Ag ₂sO ₄, 1.5mol/lKSCN and 0-2mol/L NH ₄the electrolytic solution of Cl, can obtain porous silverskin.KSCN is selected to be to prevent Ag in document ₂sO ₄produce with Cl-and precipitate, adopt NH ₄cl is because can produce a certain amount of H ⁺and produce bubble hydrogen, make electrode produce cell texture.But in this electrolyte combination, AgSCN and AgCl all can bring larger Raman background interference.Therefore, in the selection of electrolytic solution, few ionic species as far as possible should be selected to combine.In order to obtain porous silverskin, in electrolytic solution, a certain amount of Ag must be contained ⁺and H ⁺.If select AgNO ₃and HNO ₃as electrolytic solution, due to NO ₃ ⁺directly Ag can be dissolved under sour environment, so after electro-deposition completes, the HNO in electrolytic solution ₃directly can react with the silverskin deposited, and destroy its cell texture, so get rid of AgNO ₃.The present embodiment is finally with Ag ₂sO ₄and H ₂sO ₄for electrolytic solution, conductive matrices carries out electro-deposition, obtain the substrate with SERS effect.This electrolyte combination avoids the Raman spectrogram interference of some ions, has good porous pattern and thickness under suitable current density simultaneously.

The Ag at 0.01mol/L shown in Fig. 1 (a) ₂sO ₄with the H of 0.6mol/L ₂sO ₄electrolytic solution in, with the Raman spectrogram of the substrate obtained after the galvanostatic deposition 30s of 0.03A.Can see at 500cm ^-1, 600cm ^-1, 1000cm ^-1, 1200cm ^-1and 2150cm ^-1respectively there is a peak left and right, considers the impurity that there is material He may occur in electrolytic solution, suspects that these peaks may be due to the SO in electrolytic solution ₄ ^2-electrode surface is remained in when taking out after electrode deposition completes.To Ag ₂sO ₄pure solid sample test, can at 500cm ^-1, 600cm ^-1, 1000cm ^-1, 1200cm ^-1this four peaks and Ag ₂sO ₄peak that solid pure sample records under Raman overlaps, and thus can infer has Ag on the Nano Silver of obtained substrate surface ₂sO ₄existence, and Ag ₂sO ₄peak height very high, can the detection of severe jamming testing sample.In addition, because Nano Silver has SERS effect and Ag ₂sO ₄no, therefore, Ag ₂sO ₄the SERS effect of substrate surface can be affected, so must remove or reduce Ag ₂sO ₄content, reduce Raman background interference.

The present embodiment is attempted use and is compared Ag ₂sO ₄the Ag that stability constant is larger ⁺and SCN ^-complex compound (k _w=10 ^10.8) and Ag ⁺and S ₂o ₃ ^2-complex compound (k _w=10 ^14.15) substrate surface is cleaned, make cleaning ion and Ag ⁺ag is compared in formation ₂sO ₄more stable complex compound, thus reach wash-out SO ₄ ^2-object.Substrate after electro-deposition is first cleaned with ultrapure water, after in KSCN solution, soak 3min, then with super water cleaning substrate surface.Because of KSCN can and Ag ⁺ag is compared in formation ₂sO ₄more stable complex compound, can by the Ag of substrate surface ₂sO ₄be further converted to Ag ⁺with SCN ^2-complex compound.The collection of illustrative plates obtained, as shown in Fig. 1 (b), can see original Ag ₂sO ₄peak almost disappear, but at 2200cm ^-1there is a very large peak left and right, at 743cm ^-1and 888cm ^-1place is new there are two small peaks, infers that this peak is the new interference that AgSCN sediment brings, KSCN therefore can not be adopted to clean.

Due to Ag ⁺and S ₂o ₃ ^2-the stability constant of complex compound is 10 ^14.15, with Ag ⁺and SCN ^-the stability constant of complex compound is compared, and adds 4 orders of magnitude, and the Ag formed ⁺and S ₂o ₃ ^2-complex compound can be dissolved in the water, and can not form solid.Fig. 1 (c) is the substrate after electro-deposition at Na ₂s ₂o ₃sERS collection of illustrative plates after middle rinsing.Can see, Ag ₂sO ₄disappear, only at 1600cm ^-1there is a smaller peak left and right, is speculated as a small amount of residual S ₂o ₃ ^2-peak, obtained substrate has good baseline.Further as can be seen from scanning electron microscope (SEM) photograph (Fig. 2), clean front Nano Silver surface coverage one deck Ag ₂sO ₄, and after cleaning, Nano Silver is exposed, Ag ₂sO ₄remove.Therefore with more stable and water-soluble Ag complex compound removing Ag ₂sO ₄method be feasible, can be used for processing the surface disturbance of the substrate obtained by this electro-deposition method.

In sum, the present invention proposes a kind of method that can be used for the SERS substrate Raman background signal removal that electrodeposition process makes, the nano metal electrode generally used in electro-catalysis field can be removed through the selection of suitable electrolytic solution and surface disturbance and be applied in Raman spectrum detection by the method, has larger application prospect.

Claims

1. a Raman spectrum base background signal minimizing technology for electrodeposition process making, utilizes electrodeposit reaction to increase the Raman detection signal of matrix surface, and cleans the impurity staying its surface, it is characterized in that comprising following steps:

(1) ionic species of less than three kinds is selected to carry out electrodeposit reaction as electrolytic solution to conductive substrates;

(2) the substrate ultrapure water after electrodeposit reaction is cleaned;

(3) clean the sediment remaining in substrate surface, the complex compound that Selection radio sediment stability constant is larger cleans, and complex compound itself should not have the matrix Raman back of the body or only have a small amount of interference;

(4) again substrate ultrapure water is cleaned.

2. the Raman spectrum base background signal minimizing technology that makes of electrodeposition process as claimed in claim 1, is characterized in that: be chosen as Ag to the electrolytic solution that conductive substrates carries out electrodeposit reaction in step (1) ₂sO ₄and H ₂sO ₄mixed liquor; Step is chosen as Na to the complex compound that sediment cleans in (3) ₂s ₂o ₃.

3. a Raman spectrum base background signal minimizing technology for electrodeposition process making as claimed in claim 2, is characterized in that: the Ag selecting 0.01mol/L in step (1) ₂sO ₄with the H of 0.6mol/L ₂sO ₄mixed liquor as electrolytic solution, with the continuous current of 0.03A energising 30s electrodeposit reaction is carried out to conducting base.