Procedure For The Manufacturing Of Nanostructured Platinum

Abstract

A method for the manufacturing of platinum nanostructures showing improved properties and usable in biomedical appliances is provided. The method includes providing a solution containing hexachloroplatinate with the remainder being water and electrochemical deposition of platinum on a substrate with the platinum deposited in a nanostructured form.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is a continuation of International Application No. PCT/EP2018/067222, filed on Jun. 27, 2018, which claims priority to and the benefit of DE 10 2017 114 200.2, filed on Jun. 27, 2017. The disclosures of the above applications are incorporated herein by reference.

FIELD

[0002] The present disclosure relates to a procedure for the manufacture of nanostructured platinum as well as the use of a substrate with deposited nanostructured platinum manufactured in accordance with the procedure according to the present disclosure.

BACKGROUND

[0003] The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.

[0004] Procedures for the deposition of platinum on substrates are well-known in the art. In a first alternative procedure, a platinum containing substance, for example hexachloroplatinate, is dissolved together with a reducing agent such as formic acid. Due to the reduction potential of the formic acid, the platinum compound is reduced, and platinum is deposited on a substrate. These procedures are known as passive procedures for the depositing of platinum. Passive procedures for the depositing of platinum are, for example, used in connection with the manufacturing of platinum catalysts. Since the reduction of the platinum compound starts immediately after mixing the same with the reducing agent, the reaction can only be further influenced by a change of temperature or by the time the substrate on which the platinum deposits remains in the solution. The solution prepared can only be used once. The result is an uncontrolled deposition of platinum on surfaces of a substrate and on surfaces of the reaction vessel.

[0005] There is another procedure for the deposition of platinum from platinum containing compounds in a solution. This deposition procedure is similar to the first passive process described above, however, in addition to a reducing agent, an electrolyte or a nucleating agent is used, and this is also known as an electrochemical process. By this, the deposition is enhanced in time by the use of an electrical signal. However, the deposition starts after mixing the platinum containing compound with the reducing agent, so that at least in part an uncontrolled deposition of the platinum takes place. However, due to the use of an additional electrochemically driven step, the platinum is advantageously deposited on the electrical connected substrate instead of other surfaces in the reaction vessel, and, in addition, the deposition time is reduced. Such a procedure is for example disclosed in WO 2007/050212 A2, where a new kind of a platinum deposition, called platinum grey, is described to be manufacturable under certain conditions. In the electrochemical driven process described therein, a constant voltage is used, and as a platinum containing compound platinum tetrachloride (PtCl.sub.4) is used. In addition, sodium dihydrogen phosphate and disodium hydrogen phosphate as a buffer are used in the platinum containing solution. The platinum salt concentrations used are from 3 to 30 millimoles (mM). Similarly, DE 10 2014 006 739 B3 discloses a process for the deposition of various metals, including platinum, in a solution containing lead acetate-trihydrate. Lead acetate is used in order to first deposit lead on a substrate, and afterwards the lead is substituted by platinum in a further deposition process.

[0006] All the known procedures for the deposition of platinum suffer in that a reducing agent or an additional electrolyte such as disodium hydrogen phosphate or a kind of a nucleating agent such as lead acetate are used. In the deposition layer thus created on a substrate, at least minor amounts of said compounds are incorporated, limiting the use of such substrates especially for biomedical applications, but also other uses. Further, as far as reducing agents are used in the production of a deposition layer of platinum on a substrate, the procedure is at least in part not controllable in detail. Further, in most known procedures the passive reduction of the platinum containing compound could not be stopped, so that the platin containing solution cannot be used any further, thereby increasing the costs of said procedures.

[0007] The present disclosure addresses these issues and other issues related to an alternative method for the deposition of platinum, especially in a nanostructured form.

SUMMARY

[0008] This section provides a general summary of the disclosure and is not a comprehensive disclosure of its full scope or all of its features.

[0009] The present disclosure provides for an advanced procedure for the manufacturing of nanostructured platinum, which is costly attractive, controllable and yields in highly purified platinum deposition layers.

[0010] In one form of the present disclosure, the procedure (also referred to herein as a "method") in accordance with the present disclosure for the manufacturing of nanostructured platinum comprises in a first step providing a solution containing hexachloroplatinate with the remainder water; and, in a second step, the electrochemical deposition of platinum on a substrate such that the platinum is deposited in a nanostructured form. In some variations, the solution contains only water and hexachloroplatinate, and no further active agents such as a reducing agent, a nucleating agent or a buffer solution, among others. The term "hexachloroplatinate" is to be understood in the sense of the present disclosure as to refer to the free acid with the chemical formula H.sub.2PtCl.sub.6, also called hydrogen hexachloroplatinate. Only very small amounts of impurities may be present in the solution, containing hexachloroplatinate acid and water. The concentration of such impurities shall be less than 10 mM, for example less than 3 mM, less than 1 mM, or less that 0.1 mM. As the case may be, an electrolyte as a non-active substance may be present in the solution, such as sodium or potassium chloride, especially in small amounts of not more than approximately 10 nM. In some variations the solution only contains hexachloroplatinate and water.

[0011] One advantage of using a solution in accordance with the present disclosure is that highly purified platinum deposition layers are provided by the procedure in accordance with the present disclosure, and such layers can be used in biomedical applications such as the measurement of brain currents and other applications. Further, due to the electrochemical deposition in the second step, a completely controlled process is provided for avoiding passive platinum deposition. Thus, the deposition is truly restricted to the electrical connected substrate and can be performed for long times without having an overall passive coating of platinum structures on the substrate as well as the reaction vessel. Further, in the absence of any other agent, the pH-value of the solution used is in a range such that desired substrate materials, such as polymers or non-noble metals such as steel can be coated without side effects or the destruction of the substrate itself. In some variations, the pH-value of the solution provided for in the first step is in a range between approximately 1.5 and approximately 4.0. In at least one variation the pH-value is between approximately 1.8 and approximately 39, for example approximately 2.0 and approximately 3.0.

[0012] Various materials may be used to form the substrate. As may be described below in connection with the examples in accordance with the present disclosure, for example a polyimide substrate may be used. Polyimide substrates may be provided for in a flexible form. In the polyimide itself, electrical conductive tracks, e.g., tracks made of platinum, can be embedded within the polyimide material. Such embedded tracks have on their first end region an active side with a surface being in contact with the deposition solution, being thus not embedded, whereas on the second end region an interconnection is provided for by the embedded track, being not in contact with the depositing solution. Such polyimide substrates may have, for example, as active sides a circular shape with a diameter great than ABOUT 5 .mu.m, for example greater than 100 .mu.m, or greater than 2000 .mu.m, and even more. However, also other polymers may be used as substrate materials, such as silicone rubber (e.g. PDMS), parylene (e.g. Parylene-C), or epoxy resins such as SU-8, as well as none-noble metals such as stainless steel (e.g. 316L), nickel-cobalt-base alloys such as MP35N, or indium tin oxide (ITO). In addition, also none-noble metals may be used embedded in polymers such as polyimide, as described before. Other substrate materials useable in accordance with the present disclosure are glass or PEM (Polymer Electrolyte Membrane). One PEM usable is Nafion (registered trademark), obtainable from the company DuPont. The glass or the PEM are coated with an electrical conductive material, e.g. with platinum. However, instead of platinum, also other noble metals such as rhenium, ruthenium, rhodium, palladium, silver, osmium iridium or gold are usable.

[0013] As far as the terms "approximately", "about" or "essentially" are used in the present disclosure with respect to values, value ranges or terms referring to values, they are to be understood herein to mean what the person skilled in the art would regard as typical in the given context, and from the perspective of a person skilled in the art. In particular, deviations of the given values, value ranges or terms referring to values comprised by the aforesaid terms amount to +/-10%, for example +/-5% or +/-2%.

[0014] The term "nanostructure(d)" as used in connection with the deposited platinum on a substrate produced in accordance with the procedure of the present disclosure refers to grain-like platinum structures having an irregular outer shell with edges and corners having a grain size in a range between approximately 1 nm to approximately 500 nm, for example in a range between approximately 5 nm to approximately 400 nm, or in a range between approximately 10 nm to approximately 200 nm.

[0015] In some variations of the present disclosure, the deposition time for the electrochemical deposition in the second step of the procedure is in a range between approximately 1 s and approximately 60 min, for example in a range between approximately 1 s and 1000 s, or in a range between approximately 10 s and approximately 360 s. In at least one variation of the present disclosure, the temperature at which the deposition takes place is in a range between approximately 10.degree. C. and approximately 75.degree. C., for example in a range between approximately 15.degree. C. and approximately 62.degree. C. In some variations the concentration of the hexachloroplatinate in the solution before electrochemical deposition takes place is in a range between approximately 0.2 mM and approximately 3.1 mM, for example in a range between approximately 0.25 mM and approximately 3.0 mM, or in a range between approximately 1.0 mM and approximately 2.9 mM. By using such low concentrations of hydrogen hexachloroplatinate in the preparation of the solution in the first step of the procedure in accordance with the present disclosure, a very controlled deposition of the platinum and the form of nanostructures on a substrate are available. If the concentration of hydrogen hexachloroplatinate would exceed 5 mM, and also 4 mM, controlled deposition of platinum in the form of nanostructures is reduced or not possible. IN some variations, highly purified water is used, especially a highly purified water with a resistance of at least approximately 15 MOhm*cm, for example at least approximately 18 MOhm*cm, at 25.degree. C., such as Milli-Q (registered trademark) water of Type 1 in accordance with ASTM D1193-91 provided for by Millipore Corporation.

[0016] In another form of the present disclosure, the electrochemical deposition in the second step is carried out in a voltage range between approximately -0.6 V, for example approximately -0.4 V, and approximately +0.4 V vs. Ag/AgCl. As far as in the following voltages or voltage ranges in relation to the electrochemical deposition in the second step of the procedure in accordance with the present disclosure are referred to, they are defined vs. Ag/AgCl. In some variations, the deposition in the electrochemical step is carried out with a three (3) electrode set-up. In such a three electrode set-up, a stainless steel counter electrode is used as well as a Ag/AgCl reference electrode. As a working electrode, the electrically connected substrate used in the second step of the procedure in accordance with the present disclosure is used. However, also a two-electrode setup may be used for the electrochemical deposition. Although the electrochemical deposition in the second step in accordance with the present disclosure may be carried out at a constant potential, in some variations electrochemical deposition is carried out as a dynamic potential deposition. Such a dynamic potential deposition leads to the platinum nanostructures as defined before in form of grain-like structures with edges and corners. In contrast thereto, an electrochemical deposition at a constant potential usually leads to grass-like structures with grass needles with an extension in a range between approximately 10 nm and approximately 1000 nm, thus, a range similar to the grain-like nanostructures obtained in accordance with the procedure of the present disclosure. As a dynamic potential deposition in accordance with the present disclosure it is understood that at least over a certain voltage range with a lower vertex potential and a higher vertex potential the electrochemical deposition is carried out. In some variations, the voltage range comprises at least a sweep over a range of approximately 0.2 V, for example a sweep of a range of at least approximately 0.5 V. In at least one variation a sweep in a range between 0.2 V and 0.9 V, in one direction, is used. The dynamic potential deposition in the sense of the present disclosure may, thus, be carried out, e. g., as a linear sweep from a lower voltage to a higher voltage or a linear sweep from a higher voltage to a lower voltage, or as a cyclic sweep between a lower potential and a higher potential. Also, the inclination of the sweep may be amended within one sweep. Besides the aforesaid linear sweeps and cyclic sweeps, it is also possible to use more complex sweeps using geometries like exponential signals or sinusoidal signals, square wave functions and/or saw tooth functions, especially between two or more potentials. The latter signals or functions are applicable at frequencies between approximately 5 Hz and approximately 200 Hz. For example, a saw tooth function may be used starting from a voltage of -0.2 V with a step of +/-0.2 V at a frequency of 20 Hz. The deposition times for the aforesaid signals and functions are comparable to the deposition times already mentioned above.

[0017] The teachings of the present disclosure include using a single sweep or multiple sweeps in a given potential range in the second step of the electrochemical deposition. That is, in some variation multiple sweeps are used in a given potential range. In such variations cyclic multiple sweeps can be used. Such cyclic multiple sweeps are obtainable by using cyclic voltammetry technics. In at least one variation cyclic voltammetry in a voltage range between approximately -0.3 V and 0.3 V is used. When using multiple cyclic sweeps, at least 5 sweeps back and forth, for example at least 10 sweeps back and forth, more than approximately 20 sweeps back and forth and less than approximately 1000 sweeps back and forth are used. In some variations less than or equal to 600 sweeps back and forth are used.

[0018] In some variations of the present disclosure, a scan rate used for single sweeps or multiple sweeps, especially multiple cyclic sweeps, in a given potential range are in a range between approximately 1 mV/s and approximately 200 mV/s, for example in a range between approximately 2 mV/s and approximately 150 mV/s. In at least one variation, the total charge transferred is in an amount between approximately 0.5 C/cm.sup.2 and approximately 5 C/cm.sup.2, for example in a range between approximately 0.8 C/cm.sup.2 and approximately 4 C/cm.sup.2. The charge transferred can be used to control the deposition process in the second step of the procedure in accordance with the present disclosure in detail. The charge transferred is measured by cyclic voltammetry.

[0019] The substrate with deposited nanostructured platinum thereupon produced in accordance with the procedure of the present disclosure show very dense, grain-like platinum nanostructures on the surface of the substrate. The complex impedance Z, that may be measured by electrochemical impedance spectroscopy, of such a coated substrate is below the complex impedance of an uncoated substrate, and is lowered by a factor in a range between approximately 10 to approximately 100 in the coated substrate compared to the uncoated substrate. The complex impedance of a coated substrate produced by multiple cyclic sweeps, especially produced by cyclic voltammetry, is lower than the complex impedance of a coating produced with a constant potential process, whereby all other parameters are hold equal. The lowering of the complex impedance when using a dynamic potential process, at especially multiple cyclic sweeps, especially produced by cyclic voltammetry, compared to a constant potential process, has a magnitude of a factor between approximately 0.3 and approximately 2.5.

[0020] The present disclosure also refers to use of a substrate with deposited nanostructured platinum thereupon manufactured in accordance with the procedure as discussed before as an adhesion promoter for coatings, as a corrosion protection and/or as a means for the enhancement of electrochemical properties, such as a voltage influencing means, an impedance reducing means, or an enhancement means for charge transfer. Especially, the platinum nanostructures on a substrate produced in accordance with the present disclosure may function as an adhesion promoter for a subsequent deposition of bio-functional coatings for neural probes. Such coatings may be made, for example, by conducting polymers, especially in the form of electrodeposited films. Due to the procedure used for the manufacturing of the platinum nanostructures on a substrate, a rough layer that provides a higher amount of nucleation sites as well as a higher degree of mechanical interaction to a subsequently electrodeposited conducting polymer layer is obtainable and useable, resulting in a significantly improved adhesion of the conducting polymer electrodeposited thereupon. Further, a substrate with an electrocoating of platinum nanostructures produced in accordance with the present disclosure is useable as an intermediate layer on none-noble metal surfaces, that may be used as working electrodes. When used as a voltage influencing means, one or more layers of electrodeposited platinum nanostructures produced in accordance with the present disclosure on a substrate influence the reducing or oxidizing potential of the original surface, so that the field of use of the original surface is amended and/or widened. The present disclosure also relates to a substrate with an electrocoating made of platinum nanostructure, produced in accordance with the present disclosure, whereby a mechanical strengthening of the electrodeposited platinum nanostructure is achieved by filling the platinum nanostructure with at least one conductive polymer, e.g. PEDOT. This is especially advantageous in case the platinum nanostructures are long and/or the deposit will show a weblike structures with holes therebetween or openings. The substrate may exist of an insulation layer and a conducting electrode layer, arranged at least on a part of said insulation layer. The electrocoating of nanostructured platinum free of ions and salts is arranged at least in part on said conducting electrode layer.

[0021] The working electrodes used as substrates or the substrate itself may have each kind of geometry, depending also on the further use of the substrate with an electrodeposited platinum nanostructure thereupon produced in accordance with the procedure of the present disclosure. For example, the electrode may have a needle-like or tip-like structure, a flat structure, as already disclosed above in connection with polyimide substrates, or may have any other geometry.

[0022] In some variations cyclic voltammetry is used in a voltage range between approximately -0.3 V and 0.3 V, whereby more than 20 sweeps, and not more than approximately 1000 sweeps, for example not more than approximately 500 sweeps back and forth are used with a scan rate in a range between 1 mV/s and approximately 120 mV/s. In such variations, a concentration of the hydrogen hexachloroplatinate is in a range between approximately 1.5 mM and approximately 2.8 mM and improved mechanical properties especially when using the platinum nanostructures on the substrate as an intermediate or enabling layer for bio-functional coatings, for non-noble metal surfaces and as a voltage-influencing means are obtainable.

[0023] Further areas of applicability will become apparent from the description provided herein. It should be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure.

DRAWINGS

[0024] In order that the disclosure may be well understood, there will now be described various forms thereof, given by way of example, reference being made to the accompanying drawings, in which:

[0025] FIG. 1 is a time-potential-diagram showing possible linear sweeps A and B as well as a multiple sweeps C useable in an electrochemical deposition step, according to the teachings of the present disclosure;

[0026] FIG. 2 shows cyclic voltammetry diagrams of an uncoated substrate, a substrate produced in a constant potential process, and a substrate coated in a dynamic potential process by using cyclic voltammetry, according to the teachings of the present disclosure;

[0027] FIG. 3 shows complex impedance of the three substrates shown in FIG. 2;

[0028] FIG. 4 is a photograph of a polyimide substrate with a platinum nanostructure deposition carried out by a dynamic potential process on the left side and by a constant potential process of the right side, showing overgrowth of the deposited nanostructures, according to the teachings of the present disclosure;

[0029] FIGS. 5A to 5C are electron microscopy images of platinum nanostructures deposited on a substrate by different dynamic potential process, according to the teachings of the present disclosure;

[0030] FIG. 5D is an electron microscopy image of platinum nanostructures deposited on a substrate by a constant potential process;

[0031] FIGS. 6A and 6B are electron microscopy images of platinum nanostructures deposited on a polyimide substrate by way of a constant potential process; and

[0032] FIGS. 7A and 7B are electron microscopy images of platinum nanostructures deposited on a polyimide substrate by way of a dynamic potential process, according to the teachings of the present disclosure.

[0033] The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way.

DETAILED DESCRIPTION

[0034] The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses. It should be understood that throughout the drawings, corresponding reference numerals indicate like or corresponding parts and features.

[0035] Referring to FIG. 1, three alternatives (A, B, and C) for carrying out a dynamic potential deposition of platinum nanostructures on a substrate are shown. A linear sweep A starting from a low potential of -0.3 volts (V) and ending at a higher potential of 0.3 V is characterized in a general way, whereas a linear sweep B starting at a higher potential of 0.3 V and ending at a lower potential of -0.3 V is also shown. Further, multiple sweeps C are shown in FIG. 1 with three peaks within the time frame shown, the multiple sweeps starting at a lower potential of -0.3 V and running to a higher potential of 0.3 V back and forth. Such multiple sweeps C may be obtained by using cyclic voltammetry and is similar to a multiple sweep using a saw tooth function.

[0036] Now referring to FIG. 2, the cyclic voltammetry properties of an uncoated substrate, a substrate coated by way of a dynamic potential process, and a substrate obtained by constant potential process are shown. For the constant potential process, a potential of -0.3 V is used, whereas for the dynamic potential process, cyclic voltammetry with a voltage range between -0.3 V to 0.3 V back and forth is used. For the dynamic potential process, 300 multiple cyclic sweeps back and forth between -0.3 V and 0.3 V are used with a scan rate of 12 millivolts per second (mV/s) to deposit the nanostructures. The total charge transferred was about 2 Coulombs per centimeter squared (C/cm.sup.2). An identical charge is transferred with respect to the constant potential process to the substrate. The potential was held constant for 2310 seconds (s) at -0.3 V. The hydrogen hexachloroplatinate aqueous solution used with respect to the constant potential process as well as the dynamic potential process was identical and contained 2.5 millimoles (mM) hydrogen hexachloroplatinate. As shown in FIG. 2, the electrochemical active area of the substrate produced with the dynamic potential process is greater than the electrochemical active are of the substrate produced with a constant potential process. For the cyclic voltammetry measurements done with respect to FIG. 2, an aqueous solution of highly purified water with a phosphate buffered saline (PBS) at a concentration of 0.01 moles (M) without hydrogen hexachloroplatinate (as well as any other kind of agents) is used. The cyclic voltammetry is carried out at room temperature (25.degree. C.).

[0037] Referring to FIG. 3, the complex impedance measured by electrochemical impedance spectroscopy of the substrates is shown, as defined in connection with FIG. 2 above. One may determine from FIG. 3 that the complex impedance (with symbol |Z| and unit S2) of the coated substrates is lowered by a factor of 35 to 50 compared to the uncoated substrate. Further, the complex impedance of the substrate having platinum nanostructures electrodeposited thereupon by way of a dynamic potential process show a lowered impedance by a factor of around 1.5 compared to the substrate obtained by a constant potential process, as defined before in connection with FIG. 2. Thus, one may obtain from FIGS. 2 and 3 that the electrodeposition of platinum nanostructures by way of a dynamic potential process, especially by multiple sweeps provides a substrate with at least one layer of platinum nanostructures with desirable properties. In one form, multiple cyclic sweeps obtainable by cyclic voltammetry provide a substrate with at least one layer of platinum nanostructures with desirable properties. Indeed, as shown in FIGS. 5A to 5D (see discussion below), by way of a dynamic potential process a more homogeneous and thinner electrodeposition of platinum nanostructures on substrates is obtainable. Due to the increased homogeneity, such layers of platinum nanostructures on substrates show improved properties especially when used as intermediate layers or adhesion promotion layers as discussed before.

[0038] Now referring to FIG. 4, the coated substrates produced in accordance with the solutions and the electrochemical deposition are shown, as defined with respect to FIG. 2 above, whereby on the left-handed side of FIG. 4 the substrate with platinum nanostructures produced by way of a dynamic potential process as described above is shown, and on the right-handed side platinum nanostructures deposited on the substrate produced by the constant potential process as defined above is shown. The right-handed side of FIG. 4 shows an overgrowth of the platinum nanostructures over the rim of the active area of a substrate, whereas no such overgrowth takes place by the dynamic potential process as evidenced by the left-handed side platinum nanostructures deposited on the active area of the polyimide substrate.

[0039] FIGS. 5A to 5C show electronic microscopy images of substrates with electrocoated platinum nanostructures obtained by various dynamic potential processes, whereas FIG. 5D shows the result of a constant potential process. In FIG. 5A, the electrodeposition of platinum nanostructures was carried out using a dynamic potential process, namely a linear voltage ramp starting from a negative potential of -0.3 V and ending at a positive potential of 0.3 V. The scan rate was 2 mV/s and the total deposition time was 300 s. In contrast, FIG. 5B shows a linear voltage ramp starting from a higher potential of 0.3 V and ending at a lower potential at -0.3 V. The other conditions are identical to the linear voltage ramp as used for the deposition of platinum nanostructures shown in FIG. 5A. FIG. 5C shows platinum nanostructures deposited by a dynamic potential process using cyclic voltammetry in a potential range between -0.3 V and 0.3 V at a scan rate of 120 mV/s and fifty-eight (58) sweeps back and forth. Conversely, FIG. 5D shows the electrodeposited platinum nanostructures produced by using a constant potential of -0.3 V. The charge transferred in FIGS. 5A, 5B, and 5D was 1.1 C/cm.sup.2, whereas the charge transferred in FIG. 5C was doubled to 2.2 C/cm.sup.2. As shown for the dynamic potential process of FIGS. 5A to 5C a more homogeneous and denser surface structure of the electrodeposited layer of platinum nanostructures is obtained compared to the electrodeposited layer produced by a constant potential process in accordance with FIG. 5D. Moreover, FIG. 5D shows very coarse and grass-like platinum nanostructures with extensions between approximately 20 nanometers (nm) to approximately 700 nm, whereas the platinum nanostructures obtained by the dynamic potential process in accordance with FIGS. 5A to 5C show a grain-like structure with corners and edges, with dimensions for the grain size between approximately 25 nm to approximately 150 nm (FIG. 5A), between approximately 10 nm to approximately 100 nm (FIG. 5B), and between approximately 20 nm to approximately 200 nm (FIG. 5C). The finest nanostructures were obtained by the linear voltage ramp starting from the higher potential in accordance with FIG. 5B, whereas the most homogeneous surface structure was obtainable by using a linear voltage ramp starting from the lower potential in accordance with FIG. 5A. The structure of the platinum nanostructures produced in accordance with cyclic voltammetry as shown in FIG. 5C is in the middle between the structures of the platinum nanostructures shown in FIGS. 5A and 5B.

[0040] Referring to FIGS. 6A and 6B, electron microscopy images of an active area of a polyimide substrate coated with platinum nanostructures by way of a constant potential process are shown. The potential was held constant at -0.3 V over 220 s. The concentration of the hexachloroplatinate was 2.5 mM. From the enlargement shown in FIG. 6A one clearly sees the needle-like or grass-like structure of the platinum nanostructures produced by the constant potential process. The constant potential process further shows undefined and substantially larger structures at the edge of the substrate as a consequence of an inhomogeneous growth.

[0041] In contrast, FIG. 7 shows an active area coated with platinum nanostructures produced by the process using a dynamic potential process, namely cyclic voltammetry in a range between -0.3 V and 0.3 V at a scan rate of 120 mV/s and a total of three hundred (300) sweeps back and forth. The total charge transfer was 2.1 C/cm.sup.2, identical to the total charge transferred in the example shown in FIGS. 6A and 6B. The homogeneous and dense grain-like structure of the platinum nanostructures deposited on the polyimide substrate material shown in FIG. 7A is an enlargement of FIG. 7B. Further, the deposition area as shown in FIGS. 7A and 7B is more homogeneous and shows well defined nanostructures at the rim of the substrate in contrast to the undefined large structures resulting from the constant potential process as illustrated in FIGS. 6A and 6B.

[0042] By way of the present disclosure, it is provided a procedure for the manufacturing of platinum nanostructures from a solution containing only water and hexachloroplatinate, and yielding substrates coated with platinum nanostructures that are also usable in biomedical applications. The solution may be used at various times as no active agents such as reducing agents are present. The electrodeposited platinum nanostructures, especially when using a dynamic potential process, have a dense and homogeneous appearance with a grain-like structure with edges and corners on the grains. The deposition process is definable in detail, so that depositions of platinum nanostructures in one or more layers are obtainable with predefined properties.

[0043] Unless otherwise expressly indicated herein, all numerical values indicating mechanical/thermal properties, compositional percentages, dimensions and/or tolerances, or other characteristics are to be understood as modified by the word "about" or "approximately" in describing the scope of the present disclosure. This modification is desired for various reasons including industrial practice, material, manufacturing, and assembly tolerances, and testing capability.

[0044] As used herein, the phrase at least one of A, B, and C should be construed to mean a logical (A OR B OR C), using a non-exclusive logical OR, and should not be construed to mean "at least one of A, at least one of B, and at least one of C."

[0045] The description of the disclosure is merely exemplary in nature and, thus, variations that do not depart from the substance of the disclosure are intended to be within the scope of the disclosure. Such variations are not to be regarded as a departure from the spirit and scope of the disclosure.

Claims

1. A method for the manufacturing of nanostructured platinum, the method comprising: providing a solution containing hexachloroplatinate with the remainder water; and electrochemically depositing platinum on a substrate, wherein the platinum is deposited in a nanostructured form.

2. The method according to claim 1, wherein the solution comprises a pH-value between approximately 1.5 and approximately 4.4.

3. The method according to claim 1, wherein a concentration of hexachloroplatinate is between approximately 0.2 mM and approximately 3.1 mM.

4. The method according to claim 1, wherein the electrochemical deposition is carried out in a voltage range between approximately -0.4 V and approximately +0.4 V vs. Ag/AgCl.

5. The method according to claim 1, wherein the electrochemical deposition is carried out as a dynamic potential deposition.

6. The method according to claim 5, wherein the electrochemical deposition is carried out by a single sweep.

7. The method according to claim 5, wherein the electrochemical deposition is carried out by multiple sweeps in a given potential range.

8. The method according to claim 1, wherein a grain size of the deposited platinum is in a range between approximately 1 nm to approximately 500 nm.

9. The method according to claim 1, wherein a grain size of the deposited platinum is in a range between approximately 5 nm to approximately 400 nm.

10. The method according to claim 1, wherein a grain size of the deposited platinum is in a range between approximately 10 nm to approximately 200 nm

11. The method according to claim 1, wherein the electrochemical deposition of the platinum on the substrate comprises a dynamic potential process with multiple sweeps in a potential range between approximately 1 mV/s and approximately 200 mV/s.

12. The method according to claim 11, wherein the potential range is between approximately 2 mV/s and approximately 150 mV/s.

13. The method according to claim 1, wherein the electrochemical deposition of the platinum on the substrate comprises a total charge transferred between approximately 0.5 C/cm.sup.2 and approximately 5 C/cm.sup.2.

14. The method according to claim 1, wherein the electrochemical deposition of the platinum on the substrate comprises a total charge transferred between approximately 0.8 C/cm.sup.2 and approximately 4 C/cm.sup.2.

15. A method for the manufacturing of nanostructured platinum, the method comprising: preparing a solution containing between approximately 0.2 mM and approximately 3.1 mM hexachloroplatinate with the remainder being water, wherein the pH-value of the solution is between approximately 1.5 and approximately 4.4; placing a substrate in the solution; and electrochemically depositing platinum on the substrate using dynamic potential deposition in a voltage range between approximately -0.4 V and approximately +0.4 V vs. Ag/AgCl, wherein the deposited platinum comprises a grain size between approximately 5 nm to approximately 400 nm.

16. The method according to claim 15, wherein electrochemically depositing the platinum on the substrate comprises multiple sweeps in a potential range between approximately 1 mV/s and approximately 200 mV/s.

17. The method according to claim 15, wherein electrochemically depositing the platinum on the substrate comprises a total charge transferred between approximately 0.5 C/cm.sup.2 and approximately 5 C/cm.sup.2.

18. The method according to claim 15, wherein electrochemically depositing the platinum on the substrate comprises a deposition time between approximately 1 s and approximately 60 min.

19. A method for the manufacturing of nanostructured platinum, the method comprising: preparing a solution containing between approximately 0.2 mM and approximately 3.1 mM hexachloroplatinate with the remainder being water, wherein the pH-value of the solution is between approximately 1.5 and approximately 4.4; and electrochemically depositing platinum on a substrate using dynamic potential deposition in a voltage range between approximately -0.4 V and approximately +0.4 V vs. Ag/AgCl and a deposition time between approximately 10 s and approximately 360 s, wherein the deposited platinum comprises a grain size between approximately 10 nm to approximately 200 nm.

20. The method according to claim 19, wherein electrochemically depositing the platinum on the substrate comprises multiple sweeps in a potential range between approximately 1 mV/s and approximately 200 mV/s.

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