NOBLE METAL COATINGS WITH CONTROLLED MORPHOLOGY

Abstract

The present invention relates to a method for producing a layered body comprising at least two layers containing a noble metal in metallic form, which differ from one another in electrical conductivity, porosity, density and/or specific surface unit. The present invention also relates to a layered body obtainable by this method, an electronic component, preferably an electrode, comprising a conductive layer containing a layered body according to the invention, the use of a compound comprising a complex selected from the group consisting of the complexes (COD)Pt[O(CO)CH(C.sub.2H.sub.5)C.sub.4H.sub.9].sub.2, (COD)Pt[O(CO)C(CH.sub.3).sub.2C.sub.6H.sub.13].sub.2 and a mixture thereof, for producing a layer containing platinum in metallic form with a defined density, the use of a compound comprising a complex selected from the group consisting of the complexes (COD)Pt[O(CO)CH(C.sub.2H.sub.5)C.sub.4H.sub.9].sub.2, (COD)Pt[O(CO)C(CH.sub.3).sub.2C.sub.6H.sub.13].sub.2 and a mixture thereof for producing a layer containing platinum in metallic form having a defined specific surface.

Claims

1. A method for producing a layered body, comprising the method steps of I) providing IA) a first composition Z1 comprising an organic solvent OL1; at least one organic noble metal complex compound EKV1 dissolved or dispersed in the organic solvent OL1 at the concentration K1; and IB) a second composition Z2 comprising an organic solvent OL2; at least one organic noble metal complex compound EKV2 dissolved or dispersed in the organic solvent OL2 at the concentration K2; II) coating at least a part of the surface of a substrate with the first composition Z1 and heating the coated substrate at a temperature T1 to obtain a first layer S1 containing a noble metal in metallic form and having a thickness D1; III) coating at least a part of the first layer S1 containing a noble metal with the second composition Z2 and heating the coated substrate at a temperature T2 to obtain a second layer S2 containing a noble metal in metallic form and having a thickness D2, which second layer at least partially covers the first layer S1 containing a noble metal; wherein the organic noble metal complex compounds EKV1 and EKV2, the organic solvents OL1 and OL2, the concentrations K1 and K2, the thicknesses D1 and D2 and the temperatures T1 and T2 are selected or adapted in such a manner that the first and the second layer S1 and S2 containing a noble metal differ from one another in at least one of the following properties: (α) electrical conductivity; (β) porosity; (γ) density; (δ) specific surface unit.

2. The method according to claim 1, wherein the organic solvents OL1 and OL2, each independently of one another, are selected from the group consisting of propylene glycol n-propyl ether, ethanol or a mixture thereof.

3. The method according to claim 1, wherein the organic noble metal complex compounds EKV1 and EKV2, independently of one another, comprise platinum complexes of the type [L1L2Pt[O(CO)R.sup.1]X].sub.n, wherein L1 and L2 represent the same or different monoolefin ligands or together represent a compound L1L2 acting as a diolefin ligand, wherein X is selected from bromide, chloride, iodide and —O(CO)R.sup.2, wherein —O(CO)R.sup.1 and —O(CO)R.sup.2 represent the same or different non-aromatic C8-C18 monocarboxylic acid groups or together represent a non-aromatic C8-C18 dicarboxylic acid group —O(CO)R.sup.1R.sup.2(CO)O—, wherein said platinum complexes are mononuclear platinum complexes with n = 1, or wherein, in the event of the presence of L1L2 and/or —O(CO)R1 R2(CO)O—, may be polynuclear platinum complexes with a whole number n > 1.

4. The method according to claim 3, wherein the organic noble metal complex compounds EKV1 and EKV2, independently of one another, are platinum complexes of the formula [(L1L2)Pt[O(CO)R.sup.1].sub.2].sub.n, wherein n is equal to 1 or 2, L1L2 is cyclooctadiene or norbornadiene, and wherein R.sup.1 is a non-aromatic C7-C17 hydrocarbon group.

5. The method according to claim 3, wherein the organic noble metal complex compounds EKV1 and EKV2, independently of one another, are platinum complexes selected from the group consisting of the complexes (COD)Pt[O(CO)CH(C.sub.2H.sub.5)C.sub.4H.sub.9].sub.2, (COD)Pt[O(CO)C(CH.sub.3).sub.2C.sub.6H.sub.13].sub.2 and a mixture thereof.

6. The method according to claim 1, wherein K1 and K2, independently of one another, are within a range from 5 to 75% by weight, based on the total weight of the first composition Z1 and the second composition Z2, respectively.

7. The method according to claim 1, wherein T1 and T2, independently of one another, are within a range from 125 to 350° C.

8. The method according to claim 1, wherein D1 and D2, independently of one another, are within a range from 20 nm to 5 .Math.m.

9. The method according to claim 1, wherein the substrate comprises one or more materials selected from the group consisting of glass, ceramic, metal, plastics, modified or non-modified polymers of natural origin, cardboard, and paper.

10. The method according to claim 1, wherein the first composition Z1, the second composition Z2 or both compositions include an additive selected from the group consisting of wetting additives, rheology additives, defoamers, deaerators, additives for influencing surface tension, and odorants.

11. A layered body obtainable by the method according to claim 1.

12. A layered body comprising i) a substrate; ii) a first layer S1 which has a thickness D1, covers at least a part of the surface of the substrate and contains a noble metal in metallic form; iii) a second layer S2 which has a thickness D2, covers at least a part of the first layer S1 and contains a noble metal in metallic form; wherein the first and the second layer S1 and S2 containing a noble metal differ from one another in at least one of the following properties: (α) electrical conductivity; (β) porosity; (γ) density; (δ) specific surface unit.

13. The layered body according to claim 12, wherein the noble metal is metallic platinum.

14. The layered body according to claim 12, wherein D1 and D2, independently of one another, are within a range from 20 nm to 5 .Math.m.

15. The use of a layered body according to claim 11 for producing a conductive layer in an electronic component, preferably in an electrode, particularly preferably for producing an electrode in an electrochemical sensor.

16. An electronic component, preferably an electrode, comprising a conductive layer containing a layered body according to claim 11.

17. A use of a composition comprising an organic solvent and at least one organic noble metal complex compound which is dissolved or dispersed in the organic solvent and contains at least one complex selected from the group consisting of the complexes (COD)Pt[O(CO)CH(C.sub.2H.sub.5)C.sub.4H.sub.9].sub.2, (COD)Pt[O(CO)C(CH.sub.3).sub.2C.sub.6H.sub.13].sub.2 and a mixture thereof, preferably (COD)Pt[O(CO)C(CH.sub.3).sub.2C.sub.6H.sub.13].sub.2, for producing a layer containing platinum in metallic form and having a density corresponding to at least 90% of the theoretical density of platinum.

18. A use of a composition comprising an organic solvent and at least one organic noble metal complex compound which is dissolved or dispersed in the organic solvent and contains at least one complex selected from the group consisting of the complexes (COD)Pt[O(CO)CH(C.sub.2H.sub.5)C.sub.4H.sub.9].sub.2, (COD)Pt[O(CO)C(CH.sub.3).sub.2C.sub.6H.sub.13].sub.2 and a mixture thereof, for producing a layer containing platinum in metallic form and having a specific surface unit of at least 1 × 10.sup.6 m.sup.-1.

19. A use of a layer containing platinum in metallic form and having a specific surface unit of at least 1 × 10.sup.6 m.sup.-1 in an electrode of an electrochemical sensor, the sensitivity of which depends on the porosity of the electrode.

20. The use according to claim 19, wherein the layer containing platinum in metallic form has been produced by a method comprising the method steps: A) providing a composition comprising an organic solvent and at least one complex selected from the group consisting of the complexes (COD)Pt[O(CO)CH(C.sub.2H.sub.5)C.sub.4H.sub.9].sub.2, (COD)Pt[O(CO)C(CH.sub.3).sub.2C.sub.6H.sub.13].sub.2 and a mixture thereof; B) coating at least a part of the surface of a substrate with the composition and heating the coated substrate to obtain the layer containing platinum in metallic form and having a specific surface unit of at least 1 × 10.sup.6 m.sup.-1.

Description

[0118] The invention will now be explained in more detail with reference to non-limiting figures and examples.

[0119] FIG. 1 shows an SEM image of a layered body according to the invention comprising two layers S1 and S2 containing platinum in metallic form, wherein the layer S1 is formed by coating a substrate (polyimide) with a composition containing the PtE complex dissolved in a mixture of PnP and ethanol (1:1) and subsequent thermal decomposition of the complex at a temperature of 220° C., and the layer S2 is obtained by coating the layer S1 with a composition containing the PtV xomplex dissolved in PnP and subsequent thermal decomposition of the complex at a temperature of 200° C. The coating was performed by means of inkjet printing, with PtE lines applied in parallel at a distance of 6 mm with a width of 3 mm and a length of 50 mm (first layer S1) and PtV lines applied thereon in parallel at a distance of 5 mm with a width of 1 mm and a length of 25 mm (second layer S2), wherein the PtE and PtV lines were applied perpendicularly to one another (as shown in FIG. 5A). If necessary, the layer S1, the layer S2 and both layers can also be obtained by applying the composition containing the platinum complex several times in succession, each followed by a thermal treatment step, or by applying the composition containing the platinum complex several times in succession and then drying, wherein the thermal decomposition is then performed in the dried layers together.

[0120] FIG. 2 shows an SEM image of a layered body according to the invention comprising three layers S1, S2 and S3 containing platinum in metallic form, wherein the layer S1 is formed by coating a substrate (polyimide) with a composition containing the PtE complex dissolved in a mixture of PnP and ethanol (1:1) and subsequent thermal decomposition of the complex at a temperature of 200° C., and the layer S2 is obtained by coating the layer S1 with a composition containing the PtV complex dissolved in PnP and subsequent thermal decomposition of the complex at a temperature of 200° C., and the layer S3 is obtained by coating the layer S2 with a composition containing the PtE complex dissolved in a mixture of PnP and ethanol (1:1) and subsequent thermal decomposition of the complex at a temperature of 220° C. Here as well, the coating was applied by means of inkjet printing, with PtE lines applied in parallel at a distance of 6 mm, with a width of 3 mm and a length of 50 mm (first layer S1), PtV lines with a width of 1 mm and a length of 25 mm (second layer S2) applied in parallel at a distance of 5 mm, and PtE lines with a width of 3 mm and a length of 50 mm (third layer S3) applied again in parallel at a distance of 6 mm, wherein the PtE and PtV lines are applied perpendicularly to one another (as shown in FIG. 5B). Here was well, the layer S1, the layer S2, the layer S3 or at least two of these layers can be obtained by applying the composition containing the platinum complex several times in succession, each followed by a thermal treatment step, or by applying the composition containing the platinum complex several times in succession and then drying, wherein the thermal decomposition is then performed in the dried layers together.

[0121] FIGS. 3 shows SEM images of monolayers that differ from one another due to their density or porosity. The layer on the left (FIG. 3A) shows a layer containing platinum in metallic form obtained by coating a substrate (polyimide) with a composition containing the PtV complex dissolved in propylene glycol n-propyl ether and subsequent thermal decomposition of the complex at a temperature of 200° C. The layer in the middle (FIG. 3B) shows a layer containing platinum in metallic form, obtained by coating a substrate (polyimide) with a composition containing the PtV complex in a mixture (1:1) of PnP and ethanol and subsequent thermal decomposition of the complex at a temperature of 250° C. The layer on the right (FIG. 3C) shows a layer containing platinum in metallic form, obtained by means of coating a substrate (polyimide) with a composition containing the PtE complex in a mixture of PnP and ethanol (1:1) and subsequent thermal decomposition of the complex at a temperature of 220° C. .

[0122] FIGS. 4 shows SEM images of monolayers that differ from one another in terms of their morphology. The layer on the left (FIG. 4A) shows a layer containing platinum in metallic form, obtained by means of coating a substrate (polyimide) with a composition containing the PtV complex dissolved in propylene glycol n-propyl ether and subsequent thermal decomposition of the complex at a temperature of 200° C. The layer on the right (FIG. 4B) shows a layer containing platinum in metallic form, obtained by means of coating a substrate (polyimide) with a composition, likewise containing the PtV complex dissolved in dissolved form in propylene glycol n-propyl ether and subsequent thermal decomposition of the complex at a temperature of 200° C., wherein the layer on the right has been applied in a thickness of at least 1 .Math.m and the layer on the left in a thickness of less than 500 .Math.m. The application in a high layer thickness results in cracks in the resulting layer (see FIG. 4B), wherein the number and dimensions of such cracks likewise allow the electrophysiological properties of such a monolayer to be adapted precisely for the intended use.

[0123] FIGS. 5 shows, in non-scale form, the manner of producing the conductive layers shown in FIG. 1 (FIG. 5A) and in FIG. 2 (FIG. 5B) in the form of an SEM image. The dashed circles in FIGS. 5A and 5B indicate the area from which the SEM image in FIGS. 1 and 2, respectively, was taken.

TEST METHODS

Determination of Porosity

[0124] The pore volume and pore diameter distribution were determined with mercury porosimetry in accordance with ISO 15901-1:2016. The procedure was as follows: Sample mass 30 mg; surface tension of mercury 0.48 N/m; contact angle of mercury 140°; instrument: Porotec Pascal 140 440; measurement method: scanning; start fill pressure 0.0128 MPa; diatometer: powder, small volume; sample preparation: 8 h at 110° C. under vacuum.

Determination of the Specific Surface Unit

[0125] The specific surface unit corresponds to the ratio of the outer surface (in m.sup.2) of a body to the volume thereof (in m.sup.3), wherein the size of the outer surface is determined with nitrogen as adsorbate at 77 K in accordance with the BET theory (multipoint method, ISO 9277:2010).

Determination of Density

[0126] To determine density, the amount of deposited noble metal (e.g., platinum) is first determined gravimetrically. Subsequently, the volume of the deposited noble metal body is determined (by microscopy or — for determining the thickness of the layer — by scanning electron microscopy). The actual density thereof is determined from the ratio of the mass and the volume of the deposited noble metal body. In the case of platinum, a theoretical density of 21.45 g/cm.sup.3 was assumed, and in the case of palladium, 11.99 g/cm.sup.3.

Determination of Conductivity

[0127] Conductivity is determined by 4-point measurement in accordance with ASTM F390:2011-00 -“Standard Test Method for Sheet Resistance of Thin Metallic Films With a Collinear Four-Probe Array.”

EXAMPLES

Production Example 1: Synthesis of the PtE Complex

[0128] A solution of 65 mmol of (COD)PtCl.sub.2 in 100 ml of dichloromethane was stirred, and a solution of 260 mmol of sodium 2-ethylhexanoate in 500 ml of water was added. The two-phase mixture was emulsified for 24 h at 20° C. by vigorous stirring. The dichloromethane phase turned yellow in the process. The dichloromethane phase was separated, and the solvent was distilled off. The viscous, yellow residue was absorbed into 150 ml petroleum benzine (40-60), and the solution was dried with magnesium sulfate and filtered. The petroleum benzine was then completely distilled off. A viscous yellow residue of (COD)Pt[O(CO)CH(C.sub.2H.sub.5)C.sub.4H.sub.9].sub.2 remained.

[0129] To produce the compositions used in the method according to the invention, containing the PtE complex dissolved in an organic solvent, the residue obtained above is dissolved in the desired concentration in the respective solvent, optionally together with further additives.

Production Example 2: Synthesis of the PtV Complex

[0130] A solution of 65 mmol (COD)PtCl.sub.2 in 100 ml dichloromethane was stirred, and a solution of 260 mmol sodium10-isodecanoate in 500 ml water was added. The two-phase mixture was emulsified for 24 h at 20° C. by vigorous stirring. The dichloromethane phase turned yellow in the process. The dichloromethane phase was separated, and the solvent was distilled off. The viscous, yellow residue was absorbed into 150 ml petroleum benzine (40-60), and the solution was dried with magnesium sulfate and filtered. The petroleum benzine was then completely distilled off. A viscous yellow residue of (COD)Pt[O(CO)C(CH.sub.3).sub.2C.sub.6H.sub.13].sub.2 remained.

[0131] To produce the compositions used in the method according to the invention, containing the PtE complex dissolved in an organic solvent, the residue obtained above is dissolved in the desired concentration in the respective solvent, optionally together with further additives.

Example 1 (Production of a Layered Body with Two Layers According to the Invention)

[0132] A layered body according to the invention comprising two layers containing platinum in metallic form, which differ from one another in terms of their density and porosity, is produced. For this purpose, parallel lines are first applied to a substrate (Kapton 300 HN polyamide film) by means of inkjet printing from a composition containing the PtE complex dissolved in a mixture of PnP and ethanol (1:1) in such an amount that the composition contains 10% by weight of platinum, and the platinum complex is thermally decomposed by heating the substrate to a temperature of 220° C. Thus, as the first layer, lines containing platinum in metallic form and running parallel to one another are obtained at a distance of 6 mm, a width of 3 mm and a length of 50 mm. Parallel lines are then applied to this layer, offset by 90°, by means of inkjet printing from a composition containing the PtV complex dissolved in PnP in such an amount that the composition contains 10% by weight of platinum, and the platinum complex is thermally decomposed by heating the substrate to a temperature of 200° C. In the process, lines containing platinum in metallic form and running parallel to one another are obtained as a second layer at a distance of 5 mm, a width of 1 mm and a length of 25 mm (see FIG. 5A).

Example 2 (Production of a Layered Body with Three Layers According to the Invention)

[0133] A layered body according to the invention comprising three layers containing platinum in metallic form, which also differ from one another in terms of their density and porosity, is produced. For this purpose, parallel lines are first applied to a substrate (Kapton 300 HN polyamide film) by means of inkjet printing from a composition containing the PtE complex dissolved in a mixture of PnP and ethanol (1:1) in such an amount that the composition contains 10% by weight of platinum, and the platinum complex is thermally decomposed by heating the substrate to a temperature of 220° C. Thus, as the first layer, lines containing platinum in metallic form and running parallel to one another are obtained at a distance of 6 mm, a width of 3 mm and a length of 50 mm. Parallel lines are then applied to this first layer, offset by 90°, by means of inkjet printing from a composition containing the PtV complex dissolved in PnP in such an amount that the composition contains 10% by weight of platinum, and the platinum complex is thermally decomposed by heating the substrate to a temperature of 200° C. Thus, as a second layer, lines containing platinum in metallic form and running parallel to one another are obtained at a distance of 5 mm, a width of 1 mm and a length of 25 mm. Parallel lines are then applied to this second layer, again offset by 90° (and thus parallel to the lines of the first layer), by means of inkjet printing from a composition containing the PtE complex dissolved in a mixture of PnP and ethanol (1:1) in such an amount that the composition contains 10% by weight of platinum, and the platinum complex is thermally decomposed by heating the substrate to a temperature of 220° C. Thus, as a third layer, lines containing platinum in metallic form and running parallel to one another are obtained at a distance of 6 mm, a width of 3 mm and a length of 50 mm (see FIG. 5B).

Example 3 (Production of Monolayers According to the Invention)

[0134] A first layer is obtained by means of inkjet coating of a substrate (Kapton 300 HN polyamide film) with a composition containing the PtV complex dissolved in PnP in such an amount that the composition contains 10% by weight of platinum, and subsequent thermal decomposition of the complex at a temperature of 200° C. The second layer is also obtained by means of inkjet coating of a substrate (Kapton 300 HN polyamide film) with a composition also containing the PtV complex, but now dissolved in dissolved form in a mixture (1:1) of PnP and ethanol in such an amount that the composition contains 10% by weight of platinum, and subsequent thermal decomposition of the complex at a temperature of 250° C. The third layer is obtained by means of inkjet coating of a substrate (Kapton 300 HN polyamide film) with a composition containing the PtE complex dissolved in a mixture of PnP and ethanol (1:1) in such an amount that the composition contains 10% by weight of platinum, and subsequent thermal decomposition of the complex at a temperature of 220° C. (see FIGS. 3A, 3B and 3C).

Example 4 (Production of Monolayers According to the Invention)

[0135] A first layer is obtained by means of inkjet coating of a substrate (Kapton 300 HN polyamide film) with a composition containing the PtV complex dissolved in PnP in such an amount that the composition contains 10% by weight of platinum, and subsequent thermal decomposition of the complex at a temperature of 200° C. The second layer is likewise obtained by means of inkjet coating of a substrate (Kapton 300 HN polyamide film) with a composition containing the PtV complex dissolved in dissolved PnP in such an amount that the composition contains 10% by weight of platinum, and subsequent thermal decomposition of the complex at a temperature of 200° C., wherein, however, the second layer has been applied in a significantly higher thickness compared to the first layer (see FIGS. 4A and 4B).