CN101240416B

CN101240416B - Chemical palladium-plating method on silicon used for surface enhancement infrared spectrum

Info

Publication number: CN101240416B
Application number: CN2008100343222A
Authority: CN
Inventors: 蔡文斌; 薛晓康; 彭斌; 王金意
Original assignee: Fudan University
Current assignee: Fudan University
Priority date: 2008-03-06
Filing date: 2008-03-06
Publication date: 2010-11-17
Anticipated expiration: 2028-03-06
Also published as: CN101240416A

Abstract

The invention belongs to the field of surface-enhanced infrared spectrum technology, specifically is a method for electroless palladium plating on silicon in surface-enhanced infrared spectrum. Pd inoculating seeds as catalyst are grown on the silicon surface in Pd-salt-containing hydrofluoric acid solution, and then a Pd membrane electrode is prepared in Pd chemical plating solution. The method is easy to operate; the Pd membrane electrode can be used stably for a long time and is strongly adhered to the silicon base.

Description

The method that is used for chemical palladium-plating on the surface-reinforced infrared spectrum silicon

Technical field

This patent belongs to the surface-reinforced infrared spectrum technical field, is specifically related to a kind of electrochemical surface and strengthens the method that goes up chemical palladium-plating in the infrared spectra.

Background technology

When molecular adsorption on the surface of metal particles of nanometer island structure, the infrared absorption signal obtains 10-1000 remarkable enhancing doubly, this phenomenon be called as the surface strengthen the infrared absorption effect (Surface Enhanced Infrared Absorption Effect, SEIRA).The discovery of this effect has promoted the application of infrared spectra in surface chemistry and analytical chemistry research.Surface-reinforced infrared spectrum (SEIRAS) ^[1]It is a kind of important tools of analysis of studying the electrode interface molecular structure information.The surface enhancing infrared absorption spectrum (ATR-SEIRAS) that is equipped with attenuated total reflectance attenuated total refraction (ATR) pattern has strong, the surperficial choosing rule of surface signal simply, the problem that can avoid traditional external reflectance infrared absorption spectrum (IRAS) to face,, non-uniform electric strong inadequately as surface signal, mass transfer replenish and lag behind, the interference of solution background etc.Over nearly 10 years, the ATR-SEIRAS technology is in constantly developing: the one, and the research electrode system is extended on the electrodes such as Pt family and Fe family from Au, Ag electrode; The 2nd, film-forming method prepares (comprising electroless plating, galvanic deposit and self-assembling method) from expensive, difficult conventional dry (containing evaporation, sputter, electron beam deposition) of reappearing to wet method easy, favorable reproducibility.

Particularly be infrared window commonly used with silicon, adopt electroless plating and plating growing nano metal film electrode on its reflection bottom face ripe, alternative conventional dry prepares membrane electrode.Utilize electroless plating on the silicon infrared window, to obtain to have nano-film electrodes such as active Au of SEIRA and Pt as Osawa group etc. ^[2], and this group adopts two step wet methods (electroless plating+galvanic deposit or self-assembly+electroless plating) to obtain the Pt family and the Fe family nano-film electrode of strong SEIRA effect as general policies ^[3,4]With the regulatable Au of SEIRA effect, Ag nano-film electrode ^[5]

Because Pd electrode pair oxidation small molecules such as formic acid have good catalytic activity, so Pd is a kind of crucial catalystic material in aminic acid fuel battery.In order on molecular level, to utilize the reaction process of ATR-SEIRAS technical study Pd electrode surface oxidation formic acid, must successfully prepare Pd membrane electrode on silicon infrared window surface with SEIRA effect.For this reason, Okada ^[6]Group has utilized electroless plating to prepare the Pd membrane electrode on silicon, but the adhesive power of this Pd membrane electrode and silicon is relatively poor, easily comes off after electrochemistry is cleaned in acidic solution.Therefore, this kind Pd membrane electrode practicality is relatively poor, is not suitable for studying the reaction process of Pd electrode surface oxidation formic acid.The present invention improves and has optimized the electroless plating Pd of Okada group condition, comprises the temperature and time of growth Pd crystal seed and the temperature and time of electroless plating process etc., successfully develops a kind of simple, practical Pd membrane electrode that is used for electrochemistry internal reflection SEIRAS.

Reference:

1.M.Osawa，In?Handbook?of?Vibrational?Spectroscopy；Chalmers?J.M.，Griffiths，P.R.，Eds.；John?Wiley?&?Sons：Chichester，UK，2002；Vol.1，p.785.

2.Y-X.Chen.；A.Miki.；S.Ye.；M.Osawa.J.Am.Chem.Soc.，125(2003)3680.

3.S.-J.Huo.；X.-K.Xue.；Y.-G.Yan.；Q.-X.Li.；M.Ma.；W.-B.Cai ^*.；Q.-J.Xu.；M.Osawa.J.Phys.Chem.B?110(2006)4162.

4.Y.-G.Yan.；Q.-X.Li.；S.-J.Huo.；M.Ma.；W.-B.Cai ^*.；M.Osawa.J.Phys.Chem.B?109(2005)7900.

5.S.-J.Huo.；Q.-X.Li.；Y.-G.Yan.；Y.Chen.；W.-B.Cai ^*.；Q.-J.Xu.；M.Osawa.J.?Phys.Chem.B?109(2005)15985.

6.?H.Miyake，E.Hosono，M?Osawa，T.Okada.Chem.Phys.Lett.428(2006)451.

Summary of the invention

The object of the present invention is to provide a kind of simple method that is used for chemical palladium-plating on the surface-reinforced infrared spectrum silicon, prepared Pd membrane electrode is can the long period stable to be used, and and silicon base between adhesive power strong.

The method of the chemical palladium-plating that the present invention proposes is in the hydrofluoric acid solution that contains Pd salt, grows the Pd crystal seed as catalyzer at silicon face, and then prepares the Pd membrane electrode in the Pd chemical plating bath.Concrete steps are as follows: at first silicon face is polished and clean, carried out in containing 40% ammonium fluoride solution then etching 1-3 minute; To immerse growth Pd crystal seed in the hydrofluoric acid solution that contains Pd salt, growth temperature 15-25 ℃, growth time 2-4 minute through the silicon of etching processing; Last in the chemical plating solution that with the hydrazine hydrate is reductive agent electroless plating Pd film.

Chemical plating solution is made up of for two kinds A, B among the present invention, and wherein plating bath A component is: 0.01-0.02M hydrochloric acid, 0.02-0.04M Palladous chloride, 0.15-0.4M anhydrous ethylenediamine; Plating bath B component is: 2-4M ammoniacal liquor, 0.1-0.3M hydrazine hydrate; Two kinds of plating baths are with volume ratio V _A: V _BMix at=1: 2, and the electroless plating temperature is under 30-50 ℃, and the electroless plating time is 10-30 minute.

The present invention has following advantage: easy and simple to handle, stability of solution is good, and is cheap; Use Pd as crystal seed, can avoid introducing in the chemical palladium-plating film other foreign metal (as shown in Figure 3); The adhesive power and the electroconductibility of electroless plating Pd film are improved greatly, can be conveniently used in (as shown in Figure 5) in the electrochemistry spectral investigation; The Pd film can be applicable in the on-the-spot ATR-SEIRAS research, has obtained very strong CO probe molecule absorption signal.

Description of drawings

Fig. 1 is the schematic flow sheet of electroless plating Pd film on the silicon.

Fig. 2 is that atomic force microscope (AFM) characterizes Pd film surface topography map.

Fig. 3 is the XPS spectrum figure of electroless plating Pd film.

Fig. 4 is that electroless plating Pd film is at the saturated 0.1M HClO of CO ₄Infrared spectrogram in the solution.

Fig. 5 is that electroless plating Pd film is at the saturated 0.1M HClO of CO ₄Cyclic voltammogram in the solution, potential scanning speed are 50mV/s, and illustration is that the Pd film is at 0.1M HClO ₄The cyclic voltammogram that electrochemistry is cleaned in the solution.

Number in the figure: 1 is silicon base, and 2 is the palladium crystal seed, and 3 is nanometer palladium film.

Embodiment

Further specify below in conjunction with preparation and the application of accompanying drawing and specific examples the utility model Pd membrane electrode.

Intrinsic silicon post or monocrystalline silicon piece plane are polished with aluminum oxide powder, replace ultrasonic cleaning each three times with acetone, ultrapure water successively.Mix with the vitriol oil and hydrogen peroxide again and clean silicon face.Then in containing 40% ammonium fluoride solution, carried out etching 1-3 minute; To immerse hydrofluoric acid (the 1mM PdCl that contains Pd salt through the silicon of etching processing ₂+ 0.06M HF) growth from solution Pd crystal seed was grown 2-4 minute down for room temperature 15-25 ℃; Last in the chemical plating solution that with the hydrazine hydrate is reductive agent electroless plating Pd film.

Employed chemical plating solution is made up of for two kinds A, B in this experiment, and wherein plating bath A component is: 0.01-0.02M hydrochloric acid, 0.02-0.04M Palladous chloride, 0.15-0.4M anhydrous ethylenediamine; Plating bath B component is: 2-4M ammoniacal liquor, 0.1-0.3M hydrazine hydrate.Two kinds of plating baths are with volume ratio V _A: V _BMix at=1: 2, and the silicon that surface growth is had the Pd crystal seed electroless plating 10-30 minute, can obtain surface-brightening, the Pd membrane electrode that adhesive power is very firm like this under 30-50 ℃ of temperature.Electroless plating Pd film flow process is seen Fig. 1 on the concrete silicon.

Fig. 2 is that atomic force microscope (AFM) characterizes Pd film surface topography map, and the diameter of Pd film metal nanoparticle is about 60-80nm.Fig. 3 is the XPS spectrum figure of electroless plating Pd film, does not detect the absorption signal of other metallic element among the figure except metal Pd, shows that this kind do not introduce other metallic impurity with the method for Pd salt growth crystal seed.

Fig. 4 is that electroless plating Pd film is at the saturated 0.1M HClO of CO ₄Infrared spectrogram in the solution, reference spectra is adopted in 0.8V.Detected the signal (vCO of CO absorption among the figure _L, vCO _B), and obtained very big enhancing, also detected the signal (vOH, δ HOH) of co-adsorption water simultaneously.

Claims

1. a method that is used for chemical palladium-plating on the surface-reinforced infrared spectrum silicon is characterized in that concrete steps are as follows: at first silicon face is polished and clean, carried out then etching 1-3 minute in containing 40% ammonium fluoride solution; To immerse growth Pd crystal seed in the hydrofluoric acid solution that contains Pd salt, growth temperature 15-25 ℃, growth time 2-4 minute through the silicon of etching processing; Last in the chemical plating solution that with the hydrazine hydrate is reductive agent electroless plating Pd film;

Described chemical plating solution is made up of for two kinds A, B, and wherein plating bath A component is: 0.01-0.02M hydrochloric acid, 0.02-0.04M Palladous chloride, 0.15-0.4M anhydrous ethylenediamine; Plating bath B component is: 2-4M ammoniacal liquor, 0.1-0.3M hydrazine hydrate; Two kinds of plating baths are with volume ratio V _A: V _BMix at=1: 2, and the electroless plating temperature is 30-50 ℃, and the electroless plating time is 10-30 minute.