Electrochemical Reconstruction of Metal Surfaces

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The invention relates to methods and compositions for the surface reconstruction of gold and other metal surfaces. Specifically, an applied potential and a certain solution composition, is used to reconstruct the metal surface atoms into a specific atomic lattice arrangement (symmetry). Also disclosed is a kit for the surface reconstruction of metal electrodes.

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Description
RELATED APPLICATIONS

This substitute application contains no new matter and relates to U.S. Non-Provisional patent application Ser. No. 12/329,630, which was filed Dec. 7, 2008. This application relates to and claims priority to U.S. Provisional Patent Application No. 61/007,266, which was filed Dec. 12, 2007 and is incorporated herein by reference in its entirety.

FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

The invention was made with government support under U.S. Army contract DAAD19-2-D-0001-0574. The government may have certain rights to the invention.

FIELD OF THE INVENTION

The present invention relates to methods and compositions for the reconstruction of metal surface atoms into a specific atomic lattice arrangement (symmetry) using an electrochemical technique. Specifically, the invention combines a potential sweep method and a specific solution composition to yield a specific metal surface lattice arrangement (symmetry) over the entire surface area within a few minutes.

BACKGROUND OF THE INVENTION

The type of metal, its crystal structure and defects, cleanliness and surface pretreatments can play an important role in self assembly and protein/enzyme electron transfer.3, 4, 8-11 Therefore establishing a reproducible electrode surface for the self assembly of monolayers, bilayers and enzymes or proteins was considered using electrochemical surface reconstruction. A rearrangement of surface atoms as a function of potential and solution composition, which often involves a change in the surface atoms symmetry (or atomic lattice arrangement) and roughness, is called electrochemical surface reconstruction. Surface reconstruction phenomena have been extensively studied since its proof of existence in the early 80's and literature reviews on surface reconstruction are available.12, 13

Electrochemists are interested in gold because of its inertness (resistance to oxidation) and the wide polarizable potential ranges accessible in ultra high vacuum and aqueous media.1 A few important applications of gold include jewelry, semiconductor technology, fuel cells, and as substrates for self assembling monolayers and bilayers. Gold substrates are also used as electrode platforms for immobilizing fully functional enzymes in lipid bilayers or immobilizing proteins on top of self assembled monolayers.2-4 Because of these applications and properties of gold metal, it was initially examined by this invention. Commercially available gold electrode substrates include bulk polycrystalline, evaporated, single crystal gold and gold grown on mica. In this work evaporated gold on quartz was selected for the working electrode because of the piezoelectric properties of properly cut and mounted quartz.

The piezoelectric properties enable gold quartz crystals electrodes to serve as mass sensitive weighing platforms in quartz crystal microbalances (QCMs).5-7 The QCM can resolve very small adsorption and desorption mass changes from electrode surfaces with a mass-measuring sensitivity of 0.1 nanograms. This technique uses the changes in resonance frequency of the crystal to measure the mass on the surface because the resonance frequency is highly dependent on any changes of the crystal mass. Another attractive quality is that QCM electrodes are relatively inexpensive when compared to single crystals (˜$16 versus $300) and mechanically stronger, but as with every electrode or type of metal, there are pros and cons. One problem with QCM electrodes is that gold does not adhere very well to surfaces like quartz or glass. This adhesion problem is usually overcome by depositing a thin metal undercoating such as titanium or chromium. However, based on the data obtained in this lab and earlier publish data, using a chromium adhesion layer can be problematic especially in the gold oxide potential region and so a titanium adhesion layer was used.8

SUMMARY OF THE INVENTION

The invention provides simple and effective methods and compositions for the reconstruction of gold surfaces into the specific surface lattice arrangements of (111) and (110). Those of skill in the art of electrochemistry will recognize that additional lattice arrangements could be tailored using different solution compositions and that other metals could also be tailored to specific lattice arrangements using the same or different potentials and solution compositions.

The invention provides a simple and effective methods and compositions to quickly change the metal lattice surface arrangement within a few minutes over a large area. The invention does not require large or expensive equipment to perform or interpret the results. Ultra high vacuum conditions are not required in order to perform the surface reconstructions. The reconstructions are stable in air and the metal surface can be mailed via the postal system.

The invention provides reconstruction of the metal into a specific lattice arrangement and is independent of the metal's surface area and could be applied quickly to very large sheets of metal or to nanoparticles.

The invention provides a simple and effective method for the reconstruction of the gold surface into a (111) lattice arrangement without using flame annealing.

The invention also provides for kits to reconstruct metal surfaces. These kits comprise of different chemical solutions, electrochemical cells, reference and auxiliary electrodes.

Other objects, features, and advantages of the present invention will become apparent from the following detailed description. It should be understood, however, that the detailed description and the specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows voltammogram comparisons of the evaporated gold surface as received, after potential cycling in acidic chloride solution and after potential cycling in 0.1 M PB, pH 7.4 with ATCA. The peak voltage, charge from the gold oxide cathodic stripping peak and roughness measurements are tabulated. Results from the as received electrode are in purple, after potential cycling in acidic chloride solution are in blue, and after potential cycling in 0.1M PB, pH 7.4 with ATCA are in red.

    • a Determined from electrochemical roughness scans using 448 μC/cm2 as the theoretical value.14
    • b Rf−E/C* normalized to the flattest experimental gold substrate (Au epitaxial growth on cleaved mica) in the following manner:14
      • ▭ Qred-theor/Qred-exp (Au/mica)=448 μC/cm2/358 μC/cm2=1.25
      • Therefore, each Rf−E/C value was multiplied by 1.25 to obtain an adjusted/normalized value.
    • c The root mean square (RMS) roughness known as Rq (nm) determined from AFM scans (2.5 mm×2.5 mm)
      • Values listed for the AFM analysis are from QCEs that are not depicted in FIG. 1.
      • However the AFM QCEs were treated the same as the QCEs in FIG. 1 and had similar CVs.

FIG. 2 shows atomic force microscope analysis after solution 1 and solution 2 surface reconstructions. Atomic Force Images were taken by Dr. Mike Allen at Biometrology, Inc., 851 West Midway Avenue, Alameda, Calif. 94501 USA. (Website: www.biometrology.com) The atomic force microscope (AFM) measurements were carried out using an extended MultiMode AFM (MMAFM) integrated with the NanoScope IIIa controller (Veeco Instruments, Santa Barbara, Calif.). The MMAFM was equipped with a calibrated E-type piezoelectric scanner and suspended using a custom bungee-type noise isolation system. The larger area scans were acquired using tapping mode while contact mode was used for atomic level AFM. Topographically flat subdomains were selected for atomic level scans. Results from the after potential cycling in 0.1M PB, pH 7.4 with ATCA are represented in sample 6 and after potential cycling in acidic chloride solution in sample 8.

FIG. 3 shows cyclic voltammograms in 1 mM Pb(NO3)2, 0.1 M KNO3 and 0.1 M HNO3 and the corresponding frequency changes for lead deposited on Au (111) and Au (110) surfaces. Results from the after potential cycling in 0.1M PB, pH 7.4 with ATCA are represented in blue and after potential cycling in acidic chloride solution in purple.

FIG. 4 shows cyclic voltammograms before and after both reconstructions in 0.1 M KNO3. Results from the as received electrode before reconstruction are in light blue, after potential cycling in acidic chloride solution are in purple, and after potential cycling in 0.1M PB, pH 7.4 with ATCA are in dark blue.

FIG. 5 shows solution 1 reconstruction of the gold electrode surface. Cyclic voltammogram and the corresponding frequency changes.

FIG. 6 shows solution 2 reconstruction of the gold electrode surface and CV scans in 0.1 M phosphate buffer, pH 7.4 as compared to a scan with ATCA in the 0.1 M phosphate buffer, pH 7.4. Results for CV scans in 0.1 M phosphate buffer, pH 7.4 are in blue and purple and results for CV scan with ATCA added to 0.1 M phosphate buffer, pH 7.4 are in green.

FIG. 7 shows solution 2 reconstruction of the QCM electrode. Cyclic voltammogram and the corresponding frequency changes.

 DETAILED DESCRIPTION

The invention provides compositions and analytical procedures for the electrochemical reconstruction of metal surfaces.

A. Reconstruction of Metal Surfaces

This invention uses a potential sweep method and a certain solution composition to reconstruct the surface atoms of a metal into a specific atomic lattice arrangement (or symmetry). The reconstruction occurs in an electrochemical cell which is a non-reactive container (such as Teflon) which contains a certain solution and the working, auxiliary and reference electrodes. The metal to be reconstructed is used as the working electrode and in this arrangement the potential of the working electrode is measured against the reference electrode while the current is passed between the working and auxiliary electrodes. The working electrode potential is continuously varied and switching potentials are selected as to ensure metal oxide formation and reduction in a certain solution. Depending on the solution composition, etching and redepositing, or etching and rearrangement, of the metal will also occur within the switching potential limits. The rate at which the potential is varied is a constant value. The scan rate value is selected as to ensure all reconstruction reactions are completed during the potential sweeps and that the total reconstruction time is small.

The metal first examined by this invention was gold. Other metals of interest include, but are not limited to, platinum, silver, and copper and combinations thereof. Some of these other metals may require different solution compositions, different reference and auxiliary electrodes, and different switching potentials in order to create the same atomic surface arrangements that were created with gold. For example the general chemistry rules of solubility will hinder using the same solutions for some metals and the potential at which oxide formation occurs will be different for each metal.

B. Advantages Over the Art

The invention provides several advantages over the present art. For example, the reconstruction is fast, reversible and can be applied to large or small areas, including nanoparticles.

Only enough solution is needed to cover the metal area and to allow for contact with the reference and auxiliary electrodes. This helps to eliminate hazardous waste.

The reconstruction process is fast which helps to eliminate work hours and helps to lower power costs.

Equipment such as a scanning tunneling microscope (STM), atomic force microscope (AFM), ultra high vacuum, and quartz crystal microbalance are not required in order to perform the reconstructions.

C. Kits for Metal Surface Reconstruction

The invention provides for a variety of kit compositions. A kit may be designed to reconstruct one or more metal surfaces into one or more atomic surface arrangements. Also a kit may be designed based on the size of metal surfaces to be reconstructed and its future purpose.

DEFINITIONS

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as is commonly understood by one of skill in the art to which this invention belongs at the time of filing.

The terms “reconstruction” or “electrochemical reconstruction” as used herein refers to a rearrangement of surface atoms as a function of potential and solution composition, which often involves a change in surface symmetry and roughness.

The term “solution” as used herein refers to any aqueous or nonaqueous solution used to reconstruct the metal surface.

The term “potential sweep method” as used herein refers to an electrochemical method that continuously changes the potential of the working electrode at a certain constant rate.

The term “switching potential” as used herein refers to the starting and end potentials in a potential sweep method.

The term “working electrode” as used herein refers to the metal electrode at which the reconstruction takes place.

The term “solution 1” as used herein refers to a solution of 0.01M KCl and 0.1M H2SO4.

The term “solution 2” as used herein refers to a solution of 0.1M phosphate buffer, pH 7.4 with 10 mM 2-aminothiazoline-4 carboxylic acid (ATCA)

The term “container” as used herein refers to any vessel, tank, object, device, substance, material, particles, electronic, magnetic or gravitational fields, or space used to contain and create the reconstruction.

EXAMPLES

The following examples are included to demonstrate preferred embodiments of the invention. It should be appreciated by those of skill in the art that the techniques disclosed in the examples which follow represent techniques discovered by the inventor(s) to function well in the practice of the invention, and thus can be considered to constitute preferred modes for its practice. However, those of skill in the art should, in light of the present disclosure, appreciate that many changes can be made in the specific embodiments which are disclosed and still obtain a like or similar result without departing from the spirit and scope of the invention.

Materials and Methods:

A. Equipment

An electrochemical quartz crystal microbalance (QCM), model CHI430A—(CH Instruments, Austin, Tex.), was used to measure quartz frequency changes and electrochemical measurements. Solutions were prepared using ultra pure water that was purified using a Direct-Q3 system (Millipore Corporation, Billerica, Mass.) to exhibit a resistivity of 18.2 MΩ cm. The solutions' pH were measured using a Corning model 440 pH meter (Woburn, Mass.). The Ag/AgCl, 1 M KCl reference electrodes were made in house and calibrated using a platinum wire immersed in a saturated solution of quinhydrone (Sigma-Aldrich, St. Louis, Mo.) of known pH.15 Atomic Force Images were performed by Dr. Mike Allen at Biometrology, Inc., 851 West Midway Avenue, Alameda, Calif. 94501 USA. The atomic force microscope (AFM) measurements were carried out using an extended MultiMode AFM (MMAFM) integrated with the NanoScope IIIa controller (Veeco Instruments, Santa Barbara, Calif.). The MMAFM was equipped with a calibrated E-type piezoelectric scanner and suspended using a custom bungee-type noise isolation system. The larger area scans were acquired using tapping mode while contact mode was used for atomic level AFM. Topographically flat subdomains were selected for atomic level scans.

B. Quartz Crystal Electrodes

Gold quartz crystal electrodes were obtained from International quartz crystal manufactures (ICMFG). They consisted of 1000 Å gold onto 100 Å titanium on an AT cut quartz crystal (10 MHz). The QCM electrodes geometric area is 0.2 cm2. A programmable JITO-2 reference oscillator (Mouser electronics, Mansfield, Tex.) with a reference frequency of 10.005 MHz replaced the 8.005 MHz crystal in CHI QCM. By using the Sauerbrey equation the change in mass can be determined. The Sauerbrey equation is represented by

Δ F = - 2 f o 2 Δ m A ( υ q ρ q ) 1 2 where 2 f o 2 A ( υ q ρ q ) 1 2

corresponds to the QCM sensitivity constant.

D. Chemicals

Sodium dihydrogen phosphate monohydrate (ACS reagent >99%), sodium hydroxide pellets (99.99%), potassium chloride (99.99%), potassium nitrate (>99.5%), nitric and sulfuric acid (ACS reagent), and sodium cyanide (>97%) were obtained from Sigma Aldrich. 2-aminothiazoline-4-carboxylic acid (ATCA) was purchased from ChemImpex.

E. Electrochemical Cell

A Teflon container was used throughout these experiments. All experiments employed a double junction reference electrode (DJRE) and the outer solution was replaced every two to three scans. The DJRE consisted of an outer chamber containing 0.1 M KNO3 or 0.1 M phosphate buffer, pH 7 and an inner chamber containing 1 M KCl and an AgCl coated Ag wire. A 0.5 mm diameter platinum wire served as the auxiliary electrode. All scan rates were 100 mV/s.

Example 1 Reconstruction of the Gold (110) Surface

The potential sweep method used switching potentials of −0.1 Volts and +1.5 Volts with −0.1 Volts selected as the initial starting potential. A scan rate of 100 mV/s was selected and three complete cycles were performed. A solution of 0.01M KCl and 0.1M H2SO4 (solution 1) was used to reconstruct the gold surface atoms into a gold (110) lattice arrangement. The reactions of Cl− at gold electrodes in acidic sulfate solutions has been investigated earlier however this is the first examination of the atomic arrangement of the surface atoms.14, 16-18 In solution 1 the gold is first etched in the anodic scan and then redeposited in the cathodic scan after gold oxide reduction.

Example 2 Reconstruction of the Gold (111) Surface

The potential sweep method used switching potentials of −0.1 Volts and +1.5 Volts with −0.1 Volts selected as the initial starting potential. A scan rate of 100 mV/s was selected and three complete cycles were performed. A solution of 0.1M phosphate buffer, pH 7.4 with 10 mM 2-aminothiazoline-4 carboxylic acid (ATCA) (solution 2) was used to reconstruct the gold surface atoms into a gold(111) lattice arrangement. The structure of ATCA is below:

Hoogvliet et al. showed an electropolishing effect of gold using 0.1 M phosphate buffer, pH 7.4 and with a triple-potential pulse waveform.9 The polishing process was suggested to be due to a reconstruction and a dissolution of gold under flow conditions and the applied potentials.9 However, in the presented invention, the experiments were performed in quiet (unstirred) solutions, the potential continuously changed, an organic molecule was added to the phosphate buffer and this is the first examination of the atomic arrangement of the surface atoms. There appears to be no redepositing of gold and only slight dissolution (or etching) in solution 2. FIG. 6 illustrates the difference in the gold oxide potential region when ATCA is added to phosphate buffer. The more charge and the anodic shift found in the gold oxide potential region indicates that ATCA effects the gold oxide formation.

Examples 1 and 2 Reconstruction Confirmation Using Cyclic Voltammetry, Quartz Crystal Microbalance and Atomic Force Microscopy

Cyclic voltammetry was used to recognize the electrode surface reconstruction and the results confirm the reconstruction of the surface gold atoms into a (111) and (110) atomic arrangement. The first cyclic voltammetry experiments were performed in a solution of 0.1M sulfuric acid. Cyclic voltammetry scans in dilute sulfuric acid can provide a qualitative assessment of the exposed crystal planes on the gold surface as well as the initial cleanliness.19 Multiple sharp peaks in the gold oxide potential region would suggest different crystal lattice orientations. A single sharp oxidation peak would indicate an Au(111) crystal orientated surface. FIG. 1 illustrates cyclic voltammograms (CVs) comparisons of the evaporated gold surface as received, after potential cycling in acidic chloride solution of 0.1M sulfuric and 0.01 M KCl (solution 1), and after potential cycling in 0.1M phosphate buffer, pH 7.4, with ATCA (solution 2). The initial scans usually revealed a dominant Au (111) surface character in the evaporated gold QCE purchased from the supplier. After potential cycling in acidic chloride solution the surface atoms were altered to a different lattice arrangement as suggested by the multiple peaks (Confirmed to be Au(110) by AFM). After potential cycling in solution 2 the surface was altered back to Au(111) lattice arrangement as evident by the single sharp oxidation peak. It was also found that the initial surface needed to be clean and have a dominant Au(111) character in order for the Au(110) reconstruction CVs to be similar. For some QCEs, where the initial CV was disordered in the gold oxide region, better results for the solution 1 reconstruction could be obtained if solution 2 reconstruction was performed first.

The cyclic voltammogram can be used to estimate the surface roughness. Roughness is defined as the ratio of the real surface area to the geometric surface area and can be approximated electrochemically by measuring the charge released in gold oxide reduction. 14, 20-22 Gold oxide (type I) reduction can be represented by the following reaction:20 Au2O3+6H++3e−→+2Au+3H2O. This electrochemical approach is a crude approximation to the surface roughness and is not well defined but has found some use for comparative purposes. The electrochemical roughness factor (Rf−E/C) is represented by the following equation:

R f - E / C = Q red ( exp ) Q red ( theor )

The crude approximation but usefulness of this approach can be explained using the tabulated data in FIG. 1. For example, the AFM analysis (which is considered to be more accurate) for solution 2 reconstruction has the lowest Rq value. However the Rf−E/C for solution 2 reconstruction has the largest value which is obviously contradictory to the AFM results. In addition the peak potential has slightly shifted more negative (˜13-19 mV) as compared to solution 1 reconstruction and the “as received” non-reconstructed electrode. The discrepancy in the charge values and the cathodic shift in the gold oxide reduction potential might suggest that additional chemistry is contributing to the charge. Perhaps gold oxide monolayers are more complete with the solution 2 reconstruction even though the surface roughness is lower. It has been shown that gold oxide reduction (and oxidation) is pH dependent, and that a cathodic shift in the reduction potential and the oxide charge increase is due to a pH increase at the electrode surface.20 When protons are not consumed fast enough in the gold oxide reduction an accumulation occurs at the surface increasing the pH. The reverse should be observed for a decrease in pH. In these experiments type II or III oxide should not form because the switching potential is not large enough and the oxides present are type I.20 The QCM data (data not shown) for these scans indicated that sulfates were not adsorbed on the surface after solution 2 reconstruction but were after solution 1 reconstruction. It is possible that a completed and very stable type I oxide monolayers were formed preventing sulfate adsorption but they were supposedly reduced in the cathodic scan.21 It is speculated that phosphates were absorbed after gold oxide reduction during the reconstruction and the sulfates were not able to displace them very quickly.

The shape and peak potentials of the voltammogram contain information about the nature of the exposed gold crystal surfaces when lead is deposited and removed.23-25 Lead strongly chemisorbs at the gold faces as a neutral adatom with Gibbs adsorption energies in the range 30 to 100 kJ/mol.24 In most lead deposition studies the perchlorate anion is used as the electrolyte because of its low tendency to specifically absorb on the gold/water interface.26 However, perchlorate was not available for this research at USAMRICD and so nitrate anions were used in the lead deposition. Earlier work has shown that the peak near −0.24 V is associated with lead on the Au(111) surface, and the peaks near −0.24 V and near +0.02 V implies that lead is on a Au(110) surface.10, 24, 27 The Pb voltammetry is fairly reversible for the Au(100) and Au(110) faces but not for the Au(111) face.23-25, 28 The peaks are more clearly defined on the chemically etched electrodes and are quite broadened and ill-defined on polished electrodes. The “after Cl− Recon” voltammogram in FIG. 2 shows both of these peaks which are much more reversible; just as expected for the Au(110) surface.

The frequency change measured with the QCM may be used to calculate the mass of a deposited monolayer. Using the CHI software the QCM data in FIG. 2 was smoothed with the least squares method. A least squares point of 7 and a FT cutoff of 30 (smoothed data not shown) was selected. A value of 59 Hz and 67 Hz was then read from the graph at 0.6 V. Using a mass sensitivity parameter of 1.1 ng/Hz predicted by the Sauerbrey equation,6, 7 a 59 Hz frequency change corresponds to 3.25*10−7 g/cm2 (or 1.57*10−9 mol/cm2) of lead deposited on Au(111) and a 67 Hz change corresponds to 3.69*10−7 g/cm2 (or 1.78*10−9 mol/cm2) of Pb deposited on Au(110). The diameter of lead is approx 3.501 Å whereas gold is approx 2.884 Å.29

Hz ng/Hz Pb g/cm2 Pb mol/cm2 Pb atoms/cm2 Au(111) 59 1.1 3.25 * 10−7 1.57 * 10−9 9.43 * 1014 Au(110) 67 1.1 3.69 * 10−7 1.78 * 10−9 1.07 * 1015

Lead's nearest-neighbor distance was found to be 0.3459 nm in a hexagonal array of lead atoms.30 The atomic coverage of Pb in a hexagonal close packed (hcp) monolayer of Pb is 9.4*1014 atoms/cm2 (or 1.6*10−9 mol/cm2).31 The same value was found for the Au (111) surface in this work. The slightly larger value of atoms for the Au(110) surface could also be attributed to a hcp arrangement but with additional lead atoms acting to fill in the more open surface. FIG. 4 illustrates CVs performed only in nitrate electrolyte (0.1M KNO3) before and after reconstruction of the QCEs. The “Before Recon” was initially performed on the gold QCE before any other experiments. After the solution 1 (Cl−) reconstruction a CV was again performed in nitrate electrolyte alone. The increase in double layer capacitance and its bent shape can be attributed to the increase in surface roughness and the more open and highly stepped surface arrangement of the gold atoms. Then solution 2 reconstruction was performed (after the solution 1 reconstruction) and then a CV in 0.1M KNO3 was again performed. Notice that the “After solution 2 (ATCA) Recon” is very similar to the “Before Recon”. These CV scans in 0.1M KNO3 for both reconstructions were reproducible. This reproducibility suggests that nitrate does not alter the reconstructions and that the surfaces are stable in the potential region −0.4 to 0.6 volts, which is suitable potential window for our work in protein electrochemistry.

The QCM data in FIG. 7 is very much different from the QCM data in FIG. 5. In solution 1 the gold is first etched in the anodic scan and then redeposited in the cathodic scan after gold oxide reduction. In solution 2 (FIG. 6) there appears to be no redepositing of gold and only slight dissolution (or etching). The frequency shifts from the first cyclic scan is slightly different from the second and third cycles which are nearly identical. This would suggest that the surface reconstruction is almost complete after the first cycle which also in agreement with the dilute sulfuric acid scans performed after the first and third cyclic scans. In the anodic scan some gold surface dissolution (or etching) from −0.2 V to ˜0.9 V is occurring due to the frequency increase and the frequency decrease after 0.9 volts is likely due to gold oxide formation. In the cathodic scan, the gold dissolution appears to continue throughout the entire voltage window as evident by the continuing frequency increase after the gold oxide reduction which starts around 0.6 volts. It is suggested that gold dissolution and gold oxide formation is closer to equilibrium in the 2nd and 3rd scans and this accounts for the difference between the first cyclic scan and the following cyclic scans. Future experiments are expected to confirm or suggest an alternate explanation for these differences.

The three low-index faces of gold, Au(111), Au(110) and Au(100) differ in the density of atoms on their surfaces and in their symmetry. The mostly tightly packed is Au(111) which has three-fold (trigonal) symmetry with 1.39*1015 atoms per cm2 and an atomic spacing of 0.29 Å.32 The more open Au(110), which is regarded as a highly stepped surface 2(111)-(111), has two-fold symmetry with 1.70*1015 atoms per cm2 and an atomic spacing of 0.32 nm.32, 33 Au(111) has an unit cell area of 7.19 Å2 and one atom in its unit cell. Au(110) has a unit cell area of 11.79 Å2 and two atoms in its unit cell. The atomic force microscope (AFM) can be used to obtain atomic resolution25, 34-38 and the electrochemical surface reconstructions are readily apparent in the atomic force images of FIG. 2. Other analytical procedures that have been used to obtain evidence of atomic surface reconstruction can be found in Kolb's review.12

REFERENCES

The following references, to the extent that they provide exemplary procedural or other details supplementary to those set forth herein, are specifically incorporated herein by reference. All patents and publications referred to herein are incorporated by reference.

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Claims

1. Electrochemical methods for reconstructing gold metal surfaces into a specific lattice arrangement, with each method comprising: a container, potential sweep(s), switching potentials, electrodes and a specific solution composition.

2. Electrochemical methods for reconstructing additional metal surfaces into a specific lattice arrangement, with each method comprising: a container, potential sweep(s), switching potentials, electrodes and a specific solution composition.

3. The electrochemical methods of claim 1, wherein said methods do not require equipment such as a scanning tunneling microscope (STM), atomic force microscope (AFM) or quartz crystal microbalance to perform the reconstructions.

4. The electrochemical methods of claim 1, wherein said methods do not require ultra high vacuum conditions in order to perform or preserve the reconstructions.

5. The electrochemical methods of claim 1, wherein said methods create a stable reconstructed surface that can be mailed via the postal service without complicated precautions, storage and packaging.

6. The electrochemical methods of claim 1, wherein said methods create a stable reconstructed surface that can also be stored in ultra clean conditions.

7. The electrochemical methods of claim 1, wherein these methods include a method for obtaining the lowest energy atomic surface arrangement [Au(111)] without the use of flame annealing.

8. The electrochemical methods of claim 1, wherein these methods are included in kits to reconstruct the gold surface. These kits comprise different chemical solutions, electrochemical cells, and electrodes (reference, auxiliary and working).

9. The electrochemical methods of claim 2, wherein said methods do not require equipment such as a scanning tunneling microscope (STM), atomic force microscope (AFM) or quartz crystal microbalance to perform the reconstructions.

10. The electrochemical methods of claim 2, wherein said methods do not require ultra high vacuum conditions in order to perform or preserve the reconstructions.

11. The electrochemical methods of claim 2, wherein said methods create a stable reconstructed surface that can be mailed via the postal service without complicated precautions, storage and packaging.

12. The electrochemical methods of claim 2, wherein said methods create a stable reconstructed surface that can also be stored in ultra clean conditions.

13. The electrochemical methods of claim 2, wherein these methods include a method for obtaining the lowest energy atomic surface arrangement without the use of flame annealing.

14. The electrochemical methods of claim 2, wherein these methods are included in kits to reconstruct the metal surface. These kits comprise different chemical solutions, containers, and electrodes (reference, auxiliary and working) for each metal.

Patent History
Publication number: 20090205966
Type: Application
Filed: Dec 7, 2008
Publication Date: Aug 20, 2009
Applicant: (Fredericksburg, VA)
Inventor: James B. Kelly (Fredericksburg, VA)
Application Number: 12/329,630
Classifications
Current U.S. Class: Repairing (205/115)
International Classification: C25D 5/02 (20060101);