ELECTROLYSIS DEVICE HAVING TWO BORON DOPED DIAMOND LAYERS

Abstract

The invention relates to a device for electrolysis comprising a substrate (1, 6) on which an anode formed of a first diamond layer (3) and a cathode formed of a second diamond layer (4) are provided, wherein the first (3) and second diamond layers (4) are each made of diamond doped with boron.

Claims

1.-20. (canceled)

21. An electrolysis device comprising a substrate (1, 6) on which an anode formed of a first diamond layer (3) and a cathode formed of a second diamond layer (4) are provided, said first (3) and second diamond layers (4) each being made of boron-doped diamond, Wherein the first (3) and the second diamond layer (4) are separated from each other by an electrically insulating path (5) and are arranged in such a way that, when a voltage is applied between the first (3) and the second diamond layer (4), an electric field is formed, the field lines of which run at least partially transversely to a longitudinal extension direction of the path (5).

22. The device of claim 21, wherein the diamond is doped with 100 to 10,000 ppm boron.

23. The device according to claim 21, wherein the substrate (1, 6) is (i) made of an electrically insulating material or (ii) made of an electrically conductive material which is provided with an electrically insulating layer (2) on its upper side facing the diamond layers.

24. The device according to claim 23, wherein the electrically insulating material or layer (2) is formed of at least one of the following materials: metal oxide, Si, SiC, diamond, SiO.sub.2, fireclay, ceramic, preferably porcelain, or glass.

25. The device according to claim 23, wherein between the first (3) and/or second diamond layer (4) and the electrically insulating substrate (6) or the electrically insulating layer (2) an electrically conductive intermediate layer (7) is provided, which is preferably formed of Ti, Nb or Ta.

26. The device according to claim 21, wherein the first (3) and/or the second diamond layer (4) and/or the electrically insulating layer (2) and/or the electrically conductive intermediate layer (7) are produced by means of a CVD process.

27. The device according to claim 21, wherein a thickness of the first (3) and second diamond layers (4) is 5 to 100 μm.

28. The device according to claim 21, wherein a surface (O) of the first (3) and second diamond layers (4) facing the substrate (1, 6) is formed by more than 50% each of facets (11) forming the (111) or (001) planes of diamond crystals, preferably of diamond single crystals (10) grown together.

29. The device according to claim 28, wherein the diamond single crystals (10) extend predominantly in a [111] or [110] direction from the substrate (1, 6) or an intermediate layer (7) provided between the substrate (1, 6) and the respective diamond layer (3, 4) to the surface (O) of the respective diamond layer (3, 4).

30. The device according to claim 21, wherein the path (5) has a width of 2 to 500 μm.

31. The device according to claim 21, wherein the path (5) is meandering.

32. The device according to claim 21, wherein a metal layer (12) is provided on the first (3) and/or second diamond layer (4) in a portion outside the path.

33. The device according to claim 32, wherein the metal layer (12) is formed of a self-passivating metal or of a noble metal.

34. The device of claim 33, wherein the metal includes, as a major constituent, any one of the following elements: Ti, Ta, Nb, Cr, Al, W, Au, Ag.

35. The device according to claim 32, wherein between the metal layer (12) and the surface (O) of the first (3) and/or second diamond layer (4), a further intermediate layer (13) formed of a metal carbide, preferably TiC or WC, is provided.

36. The device according to claim 21, wherein a cover layer (8) of an electrically insulating material, preferably of diamond, is provided on the first (3) and/or second diamond layer (4) at least in sections.

37. The device according to claim 32, wherein the cover layer (8) or a further cover layer (14) of an electrically insulating material is provided on the metal layer (12).

38. Method for electrolysis, in particular for the production of OH radicals, oxidized chlorine compounds, oxidants, ozone, hydrogen, oxygen and/or for the cathodic precipitation of metals or metal compounds, comprising the following steps: contacting the first (3) and second diamond layers (4) of the device according to any one of the preceding claims with an aqueous electrolyte, and applying a voltage of 3 to 60 volts between the first (3) and second diamond layer (4), whereby an electric field is formed, the field lines of which run at least partially transversely to a longitudinal direction of the path (5).

39. Use of the apparatus according to claim 21 for producing OH radicals, oxidized chlorine compounds, ozone, hydrogen and/or oxygen.

Description

[0028] In the following, embodiments of the invention are explained in more detail with reference to the drawing. It shows:

[0029] FIG. 1 a schematic sectional view through the layer sequence of a first device,

[0030] FIG. 2 a schematic cross-sectional view through the layer sequence of a second device,

[0031] FIG. 3 a schematic cross-sectional view through a layer sequence of a third device,

[0032] FIG. 4 a schematic top view of a device for electrolysis,

[0033] FIG. 5 a schematic sectional view through a first diamond layer deposited on an intermediate layer,

[0034] FIG. 6 a schematic cross-sectional view through a layer sequence of a fourth device,

[0035] FIG. 7 a schematic top view of the device according to FIG. 6.

[0036] In the first device shown in FIG. 1, an electrically insulating layer 2 is provided on an electrically conductive substrate 1, which may be made of Ti, for example. The electrically insulating layer 2 may be made of non-doped diamond, for example. A resistance of the electrically insulating layer 2 is greater than a resistance of water, in particular when the device is used with an aqueous electrolyte.

[0037] The first diamond layer 3 and the second diamond layer 4 are provided on the electrically insulating layer 2. The first diamond layer 3 and the second diamond layer 4 are electrically separated from each other by a path 5. The path 5 can optionally also extend through the electrically insulating layer 2 (not shown here).

[0038] In the second device shown in FIG. 2, an electrically conductive intermediate layer 7 is provided on an electrically insulating substrate 6, on which the first diamond layer 3 and the second diamond layer 4 are provided. The path 5 passes through both the first 3 and second diamond layers 4, and the electrically conductive intermediate layer 7. The electrically insulating substrate 6 may be made of, for example, porcelain, SiC, Al.sub.2O.sub.3 or the like. The electrically conductive intermediate layer 7 may be made of, for example, Ti, Nb or Ta. The electrically conductive intermediate layer 7 may also be omitted. In this case, therefore, the first 3 and second diamond layers 4 are provided directly on the electrically insulating substrate 6, and an intermediate carbide layer having a thickness in the range of 1 nm to 10,000 nm may be provided between the diamond layers 3, 4 and the substrate 6.

[0039] In the third device shown in FIG. 3, in contrast to the second device shown in FIG. 2, a cover layer 8 is provided on each of the first 3 and second diamond layers 4, which cover layer 8 is formed from an electrically insulating material. This may be an electrically insulating diamond.

[0040] FIG. 4 shows a top view of a device according to the invention, such as corresponding approximately to the first or second device according to FIG. 1 or 2. The first diamond layer 3 and the second diamond layer 4 are electrically separated from each other by the path 5. The path 5 may have a width B in the range of 2 to 500 μm. The path 5 is suitably formed after depositing a boron-doped conductive diamond layer on an electrically insulating substrate or layer by laser or ion etching. It expediently has a meandering course.

[0041] FIG. 5 schematically shows a section of the device shown in FIG. 2. A TiC layer 9 is formed on an electrically conductive intermediate layer 7 made of Ti, for example, which serves as a growth layer for the diamond crystals. From the TiC layer 9, diamond single crystals 10 extend to more than 50%. The facets of the diamond single crystals 10 denoted by the reference sign 11 are formed from either the (111) plane or the (001) plane. The reference sign P denotes the growth direction of the diamond single crystals 10.

[0042] A surface O of the first diamond layer 3 is formed by the totality of the facets 11. The second diamond layer 4 is formed analogously to the first diamond layer 3.

[0043] A current flow occurs between the first diamond layer 3 and the second diamond layer 4 substantially perpendicular to the growth direction P or across the path 5.

[0044] FIG. 6 shows a schematic cross-sectional view through the layer sequence of a fourth device. The fourth device is similar to the second device shown in FIG. 2. A metal layer 12 is provided here in sections on a surface of the first diamond layer 3 and the second diamond layer 4, respectively. The metal layer 12 may optionally be bonded to the surface of the diamond layers 3, 4—as shown in FIG. 6—by means of an interposed metal carbide layer 13. A polymer layer 14 may be provided on the surface of the metal layer 12 to protect it. Instead of the polymer layer 14, a passivation layer may also be provided. The polymer layer and/or the passivation layer are optional.

[0045] FIG. 7 shows a schematic top view on the fourth device according to FIG. 6. The metal layer 12 is provided only in sections on the first 3 and the second diamond layer 4, which are located outside the structures forming the meandering path 5.

LIST OF REFERENCE SIGNS

[0046] 1 electrically conductive substrate

[0047] 2 electrically insulating layer

[0048] 3 first diamond layer

[0049] 4 second diamond layer

[0050] 5 path

[0051] 6 electrically insulating substrate

[0052] 7 electrically conductive interlayer

[0053] 8 cover layer

[0054] 9 TiC layer

[0055] 10 diamond single crystal

[0056] 11 facet

[0057] 12 metal layer

[0058] 13 metal carbide layer

[0059] 14 polymer layer

[0060] B broad

[0061] O surface

[0062] P growth direction