Anode, electrochemical cell, apparatus and use of an anode

Abstract

To overcome the activity-stability dilemma of anodes in a water electrolyser, an anode (10) comprises: - a carrier (12) having a first carrier surface area (12a) and consisting of a carrier material that comprises an electrically conductive material, - a base (14) consisting of a base material that comprises a first HEO, and - a first cap layer (16) consisting of a first cap material that comprises a first metal oxide; wherein - the base is at least partially arranged between and in electrically conductive connection with at least one part of the first carrier surface area and at least one part of the first cap layer; and - the first HEO is unequal to the first metal oxide.

Description

[0001] ANODE, ELECTROCHEMICAL CELL, APPARATUS AND USE OF AN ANODE

[0002] The present invention relates to an anode, an electrochemical cell with such anode, an apparatus with such electrochemical cell, and uses of such anode.

[0003] Implementation of water electrolysers for green hydrogen production is hampered by the activity-stability dilemma: the most active catalysts for the anodic oxygen evolution reaction, abbreviated as OER, are chemically unstable under reaction conditions, while the most stable catalysts lack sufficient activity - cf. CHANG, S. H. et al. Functional Links between Stability and Reactivity of Strontium Ruthenate Single Crystals during Oxygen Evolution. Nature Communications 2014, 5, 4191, DOI: 10.1038 / ncomms5191; and DANILOVIC, N. Activity-Stability Trends for the Oxygen Evolution Reaction on Monometallic Oxides in Acidic Environments. Phys. Chem. Lett. 2014, 5, 14, 2474-2478, DOI: 10.1021 / jz501061n.

[0004] Technologically, this translates into an increasing anodic dissolution rate with increasing catalyst activity - cf. ZERADJANIN, A. R. et al. Activity and Stability of Oxides During Oxygen Evolution Reaction - From Mechanistic Controversies Toward Relevant Electrocatalytic Descriptors. Frontiers in Energy Research 2021, 8, January, 1-17, DOI:

[0005] 10.3389 / fenrg.2020.613092. The anode, which makes about 25 % of the cost in today's alkaline electrolysers stacks, is chemically dissolved during operation. This increases operation cost, hampers continuous operation and is environmentally problematic, necessitating waste treatment to remove harmful dissolved species. The perovskite-type high-entropy oxide, abbreviated as P-HEO, with the following molecular formula promises high activity and high stability simultaneously: La(Cro.2Mno.2Feo.2Coo.2Nio.2)03-5, wherein 0 < 6 < 1 - cf. KANTE, M. V. et al. A High-Entropy Oxide as High-Activity Electrocatalyst for Water Oxidation. ACS Nano 2023, 17, 6, 5329-5339, DOI: 10.1021 / acsnano.2c08096. A high activity results from diverse active sites with unique arrangements of multiple catalytic elements, whereas a high stability can be attributed to a thermodynamic phase stabilization through a high entropy of mixing.

[0006] The object of the invention is to provide an anode that, in comparison with the prior art, exhibits or at least promises higher stability with comparable or essentially unchanged or insignificantly reduced activity, higher activity with comparable or essentially unchanged or insignificantly reduced stability, or both higher stability and higher activity, especially when used in a water electrolyser.

[0007] Against this background, the invention proposes the objects of the independent claims. Advantageous embodiments of the invention are described in the dependent claims.

[0008] In the following, the term "connection" in an expression of the type "A is in connection with B" includes in a first alternative the terms "direct connection" or "contact", and in a second alternative the term "indirect connection", and thus corresponds in the first alternative to expressions of the type "A is in direct connection with B" or "A is in contact with B", and in the second alternative to an expression of the type "A is in indirect connection with B". Such indirect connection may be realized, e.g., by means of an intermediate member C that is in contact or direct connection with A and B.

[0009] In the following, a high entropy oxide, abbreviated as HEO, is defined as a complex oxide that contains 4, 5 or more elements on the same cation site and that may have an amorphous or a crystalline structure. For example, an oxide of the type BOXhas only one, single cation site designated B. Examples are: (Mgo^Nio^Cuo^Coo^Zno^jO, or (MgNiCuCoZn)o.20 for short, in a rock salt structure, in which (MgNiCuCoZn)0.2 forms the B- site; and (Gdo.2Lao.2Ceo.2Hfo.2Zro.2)02, or (GdLaCeHfZr)0.2O2for short, in a fluorite structure, in which (GdLaCeHfZr)0.2 forms the B-site. In contrast, an oxide of the type ABOXhas two cation sites designated A and B. Examples are: Sr(Zro.2Sno.2Tio.2Hfo.2Mn0.2)03, or Sr(ZrSnTiHfMn)o.203for short, in a perovskite structure, in which Sr forms the A-site and (ZrSnTiHfMn)0.2 forms the B-site; and (Gdo.4Euo.4Smo.4Ndo.4Lao.4)Zr207, or (GdEuSmNdLa)o4Zr207 or (GdEuSmNdLa)o.2Zr03.5 for short, in a pyrochlore structure, in which (GdEuSmNdLa)0.2forms the A-site and Zr forms the B-site.

[0010] In the following, the term "electrically conductive", as for example in "electrically conductive material" or "electrically conductive connection", refers to both electronic conductivity, enabled by electrons - including defect electrons or electron holes - as the charge carriers, and ionic conductivity, enabled by ions or protons as the charge carriers. An electrically conductive material and an electrically conductive connection each has the ability to conduct an electrical current, including electronic current and ionic current. The invention, according to a first aspect, proposes an anode, comprising:

[0011] - a carrier having a first carrier surface area and consisting of a carrier material that comprises an electrically conductive material,

[0012] - a base consisting of a base material that comprises a first HEO, and

[0013] - a first cap layer consisting of a first cap material that comprises a first metal oxide; wherein

[0014] - the base is at least partially arranged between and in electrically conductive connection with at least one part of the first carrier surface area and at least one part of the first cap layer; and

[0015] - the first HEO is unequal to the first metal oxide.

[0016] The first carrier surface area can be specified in any way as required, for example in such a way that it covers one or more separate parts of the carrier surface or the whole carrier surface, and / or that it forms a single, continuous area or comprises at least two distinct areas separated from each other.

[0017] The electrically conductive material can be specified in any way as required, for example in such a way that it comprises an electron conductive material, an ion conductive material, a proton conductive material, an alloy, a metal oxide, a proton exchange membrane, abbreviated as PEM, an ion exchange membrane, abbreviated as IEM, an anion exchange membrane, abbreviated as AEM, a cation exchange membrane and / or at least one element selected from a group that comprises Al, Ti, Ni, Cu, Fe, and Sr. Exemplarily, it comprises Nb:SrTiO3which is SrTiO3doped with Nb, wherein the mass fraction of Nb exemplarily is about 0.2 %, about 0.3 %, about 0.4 %, about 0.5 %, about 0.6 %, about 0.7 %, about 0.8 %, or about 1 %. Carrier materials comprising an electrically conductive material for use in electrochemical cells are widely known. Any kind of industrial and / or conventionally used electrically conductive material is conceivable as to form the carrier material.

[0018] The base can be specified in any way as required, for example in such a way that it has a thickness of Mb monolayers, wherein Mb is a natural number, with 1 < Mb < 50, with 1 < Mb or 5 < Mb or 10 < Mb or 15 < Mb or 20 < Mb or 25 < Mb or 30 < Mb or 35 < Mb or 40 < Mb or 45 < Mb, and / or with Mb < 5 or Mb < 10 or Mb < 15 or Mb < 20 or Mb < 25 or Mb < 30 or Mb < 35 or Mb < 40 or Mb < 45 or Mb < 50. In the present disclosure, the term "monolayer" is to be understood as a unit of measurement for the deposition of a crystalline material on a surface or on a crystalline surface, for example, of the base material on the first carrier surface area or of the first cap material on the base material. A thickness value equal to 1 monolayer means that the crystalline surface is completely covered with the deposited unit cells of the respective crystalline material. One monolayer of the oxides mentioned in the present disclosure typically has a thickness of about 0.3 nm, about 0.4 nm or about 0.5 nm. Further, the base, especially when having an amorphous structure, can exemplarily be specified to have a thickness that is at least about 0.3 nm or at least about 1.5 nm or at least about 3.0 nm or at least about 4.5 nm or at least about 6.0 nm or at least about 7.5 nm or at least about 9.0 nm or at least about 10.5 nm or at least about 12.0 nm or at least about

[0019] 13.5 nm. The base can be formed in any way as required, for example by chemical vapour deposition, abbreviated as CVD, physical vapor deposition, abbreviated as PVD, pulsed laser deposition, abbreviated as PLD, sputter deposition, electrodeposition, coprecipitation, reverse coprecipitation, Pechini methods, modified Pechini methods, sol-gel methods, modified sol-gel methods, molten salt synthesis, nebulised spray pyrolysis, or solvothermal synthesis.

[0020] The first HEO can be specified in any way as required, for example in such a way that it has an amorphous structure, a fluorite structure, a rock salt or halite structure, a perovskite structure, a pyrochlore structure, or a spinel structure.

[0021] The first cap layer can be specified in any way as required, for example in such a way that it has a thickness of Mf monolayers, wherein Mf is a natural number, with 1 < Mf < 30, with 1 < Mf or 2 < Mf or 3 < Mf or 4 < Mf or 5 < Mf or 6 < Mf or 9 < Mf or 12 < Mf or 15 < Mf or 18 < Mf or 21 < Mf or 24 < Mf or 27 < Mf, and / or with Mf < 3 or Mf < 6 or Mf < 9 or Mf < 12 or Mf < 15 or Mf < 18 or Mf < 21 or Mf < 24 or Mf < 27 or Mf < 30. Further, the first cap layer, especially when having an amorphous structure, can exemplarily be specified to have a thickness that is at least about 0.3 nm and at most about 9 nm, is at least about 0.3 nm or at least about 0.6 nm or at least about 0.9 nm or at least about 1.2 nm or at least about

[0022] 1.5 nm or at least about 1.8 nm or at least about 2.7 nm or at least about 3.6 nm or at least about 4.5 nm or at least about 5.4 nm or at least about 6.3 nm or at least about 7.2 nm or at least about 8.1 nm, and / or is at most about 0.9 nm or at most about 1.8 nm or at most about 2.7 nm or at most about 3.6 nm or at most about 4.5 nm or at most about 5.4 nm or at most about 6.3 nm or at most about 7.2 nm or at most about 8.1 nm or at most about

[0023] 9.0 nm. The first cap layer can be formed in any way as required, for example by CVD, PVD, PLD, sputter deposition, electrodeposition, coprecipitation, reverse coprecipitation, Pechini methods, modified Pechini methods, sol-gel methods, modified sol-gel methods, molten salt synthesis, nebulised spray pyrolysis, or solvothermal synthesis.

[0024] The first cap material can be specified in any way as required, for example in such a way that it consists of the first metal oxide or comprises one further or at least one further material.

[0025] The first metal oxide can be specified in any way as required, for example in such a way that it is an HEO or a non-HEO.

[0026] The invention, according to a second aspect, proposes an electrochemical cell, comprising:

[0027] - a cathode, and

[0028] - an anode that is designed according to the first aspect.

[0029] The cell can be specified in any way as required, for example in such a way that it comprises no additional or at least one additional cathode and / or no additional or at least one additional anode.

[0030] The invention, according to a third aspect, proposes an apparatus, comprising an electrochemical cell that is designed according to the second aspect. The apparatus can be specified in any way as required, for example in such a way that it comprises no additional or at least one additional electrochemical cell.

[0031] The invention, according to a fourth aspect, proposes the use of an anode that is designed according to the first aspect,

[0032] - as the anode in an electrochemical cell comprising a cathode and an anode or in an apparatus comprising a cathode and an anode;

[0033] - in an alkaline electrolyser, an alkaline water electrolyser, a solid-oxide electrolyser, a solid-oxide water electrolyser, an alkaline anion exchange membrane electrolyser, an alkaline anion exchange membrane water electrolyser, a fuel cell, a solid-oxide fuel cell, an alkaline anion exchange membrane fuel cell, or a unitized reversible fuel cell; and / or

[0034] - for electrolysis, water electrolysis, or for a recombination of hydrogen and oxygen. The invention makes it possible to overcome the activity-stability dilemma in an advantageous way and to provide a highly active anode that is very stable over time or at least an anode that, in comparison with the prior art, has higher stability with comparable or essentially unchanged or insignificantly reduced activity, or has higher activity with comparable or essentially unchanged or insignificantly reduced stability, especially when designed as an anode in a water electrolyser. This leap forward will, in the long run, reduce the production and operating costs, due to smaller dissolution rates of the anodes and higher power density of the electrolyser stack.

[0035] In an exemplary embodiment, it is specified that

[0036] - the first metal oxide has a molecular formula of ABO3-Por BOX-P, with 0 < p < 1, 1 < x < 4, X e Q, Q denoting the set of rational numbers;

[0037] - A, if present, is unequal to B and comprises at least one element selected from a group that comprises

[0038] Ca, Sc, Ga, Sr, Y, Ba, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu; and

[0039] - B comprises at least one element selected from a group that comprises Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Y, Zr, Nb, Mo, and Sn.

[0040] In these molecular formulas, |3 defines the degree of non-stoichiometry of the respective oxide, with = 0 representing the ideal or stoichiometric amount of oxygen, and x is a rational number, such as 1, 4 / 3, 3 / 2, 5 / 3, 2, 5 / 2, 3, 7 / 2 or 4. Exemplarily, the first metal oxide is LaCrO3-p, LaMnO3-p, LaFeO3-p, LaCoO3-p, or LaNiO3-p, where element La is on the A- site, and elements Cr, Mn, Fe, Co and Ni are respectively on the B-site.

[0041] In an exemplary embodiment, it is specified that the anode comprises:

[0042] - a second cap layer consisting of a second cap material that comprises a second metal oxide; wherein

[0043] - the first cap layer is at least partially arranged between and in electrically conductive connection with at least one part of the base and at least one part of the second cap layer; and

[0044] - the second metal oxide is unequal to the first metal oxide.

[0045] The second cap layer can be specified in any way as required, for example in such a way that it has a thickness of Ms monolayers, wherein Ms is a natural number, with 1 < Ms < 30, with 1 < Ms or 2 < Ms or 3 < Ms or 4 < Ms or 5 < Ms or 6 < Ms or 9 < Ms or 12 < Ms or 15 < Ms or 18 < Ms or 21 < Ms or 24 < Ms or 27 < Ms, and / or with Ms < 3 or Ms < 6 or Ms < 9 or Ms < 12 or Ms < 15 or Ms < 18 or Ms < 21 or Ms < 24 or Ms < 27 or Ms < 30. Further, the second cap layer, especially when having an amorphous structure, can exemplarily be specified to have a thickness that is at least about 0.3 nm and at most about 9 nm, is at least about 0.3 nm or at least about 0.6 nm or at least about 0.9 nm or at least about 1.2 nm or at least about 1.5 nm or at least about 1.8 nm or at least about 2.7 nm or at least about 3.6 nm or at least about 4.5 nm or at least about 5.4 nm or at least about 6.3 nm or at least about 7.2 nm or at least about 8.1 nm, and / or is at most about 0.9 nm or at most about 1.8 nm or at most about 2.7 nm or at most about 3.6 nm or at most about 4.5 nm or at most about 5.4 nm or at most about 6.3 nm or at most about 7.2 nm or at most about 8.1 nm or at most about 9.0 nm. The second cap layer can be formed in any way as required, for example by CVD, PVD, PLD, sputter deposition, electrodeposition, coprecipitation, reverse coprecipitation, Pechini methods, modified Pechini methods, sol-gel methods, modified sol-gel methods, molten salt synthesis, nebulised spray pyrolysis, or solvothermal synthesis.

[0046] The second cap material can be specified in any way as required, for example in such a way that it consists of the second metal oxide or comprises one further or at least one further material.

[0047] The second metal oxide can be specified in any way as required, for example in such a way that it is an HEO, such as, e.g., the first HEO, an HEO different from the first HEO, or a non- HEO.

[0048] In an exemplary embodiment, it is specified that

[0049] - the second metal oxide has a molecular formula of CDO3-5or DOy-5, with 0 < 6 < 1,

[0050] 1 < y < 4, y G Q;

[0051] - C, if present, is unequal to D and comprises at least one element selected from a group that comprises

[0052] Ca, Sc, Ga, Sr, Y, Ba, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu; and

[0053] - D comprises at least one element selected from a group that comprises

[0054] Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Y, Zr, Nb, Mo, and Sn. In these molecular formulas, 6 defines the degree of non-stoichiometry of the respective oxide, with 6 = 0 representing the ideal or stoichiometric amount of oxygen, and y is a rational number, such as 1, 4 / 3, 3 / 2, 5 / 3, 2, 5 / 2, 3, 7 / 2 or 4. Exemplarily, the second metal oxide is LaCrO3-5, LaMnO3-5, LaFeO3-5, LaCoO3-5, or LaNiO3-5, where element La is on the C- site, and elements Cr, Mn, Fe, Co and Ni are respectively on the D-site.

[0055] In an exemplary embodiment, it is specified that the second metal oxide is equal or unequal to the first HEO.

[0056] In an exemplary embodiment, it is specified that

[0057] - the first metal oxide is a second HEO; and / or

[0058] - the second metal oxide, if present, is a third HEO.

[0059] In an exemplary embodiment, it is specified that

[0060] - the first cap layer has a thickness that is at least about 0.3 nm and at most about 9 nm, or has a thickness of at least 1 monolayer and at most about 30 monolayers; and / or

[0061] - the second cap layer, if present, has a thickness that is at least about 0.3 nm and at most about 9 nm, or has a thickness of at least 1 monolayer and at most about 30 monolayers.

[0062] In an exemplary embodiment, it is specified that

[0063] - the first HEO, the second HEO, if present, and / or the third HEO, if present, has a molecular formula of KLO3-or LOZ-, with 0 < X < 1, 1 < z < 4, z G Q;

[0064] - K, if present, comprises at least one element or at least two, at least three, at least four or at least five elements selected from a group that comprises

[0065] Ca, Sc, Ga, Sr, Y, Ba, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu; and

[0066] - L comprises at least four or at least five elements selected from a group that comprises Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Y, Zr, Nb, Mo, and Sn.

[0067] In these molecular formulas, A. defines the degree of non-stoichiometry of the respective oxide, with X = 0 representing the ideal or stoichiometric amount of oxygen, and z is a rational number, such as 1, 4 / 3, 3 / 2, 5 / 3, 2, 5 / 2, 3, 7 / 2 or 4. It should be noted that although the same molecular formulas are used for the three HEOs, the respective elements for the K- site and L-site as well as the variables X and z can be selected individually and independently for each HEO. Exemplarily, the first, second or third HEO is LafCro^Mno^Feo^Coo^Nio^O^ , where element La is on the K-site, and (Cro.2Mno.2Feo.2Coo.2Nio.2) is on the L-site.

[0068] In an exemplary embodiment, it is specified that

[0069] - the carrier has a second carrier surface area that is adjacent to the first carrier surface area; and

[0070] - the first cap layer is at least partially arranged over and in electrically conductive connection with the second carrier surface area.

[0071] The second carrier surface area can be specified in any way as required, for example in such a way that it covers one or more separate parts of the carrier surface, and / or that it forms a single, continuous area or comprises at least two distinct areas separated from each other.

[0072] Optionally, the first cap layer is at least partially arranged over and in electrically conductive connection with the first carrier surface area.

[0073] In an exemplary embodiment, it is specified that the first cap layer is at least partially arranged between and in electrically conductive connection with the second carrier surface area and at least one part of the second cap layer.

[0074] In an exemplary embodiment, it is specified that the base is formed by or comprises a base layer consisting of the base material.

[0075] The base layer can be specified in any way as required, for example in such a way that it has a thickness, to which the above explanations on the specification of the base apply analogously. The base layer can be formed in any way as required, for example by CVD, PVD, PLD, sputter deposition, electrodeposition, coprecipitation, reverse coprecipitation, Pechini methods, modified Pechini methods, sol-gel methods, modified sol-gel methods, molten salt synthesis, nebulised spray pyrolysis, or solvothermal synthesis.

[0076] In an exemplary embodiment, it is specified that the base layer is arranged between and in electrically conductive connection with at least one part of the first carrier surface area and at least one part of the first cap layer.

[0077] In an exemplary embodiment, it is specified that the base is formed by or comprises at least two base particles consisting of the base material. Each of the base particles can be specified in any way as required, for example in such a way that it has a thickness, to which the above explanations on the specification of the base apply analogously. Each of the base particles can be formed in any way as required, for example by CVD, PVD, PLD, sputter deposition, electrodeposition, coprecipitation, reverse coprecipitation, Pechini methods, modified Pechini methods, sol-gel methods, modified solgel methods, molten salt synthesis, nebulised spray pyrolysis, or solvothermal synthesis.

[0078] In an exemplary embodiment, it is specified that the base particles are bonded to the first carrier surface area and the first cap layer.

[0079] In an exemplary embodiment, it is specified that

[0080] - the carrier has a third carrier surface area that is free of base particles and especially is adjacent to the first carrier surface area; and

[0081] - the first cap layer is at least partially arranged over and in electrically conductive connection with at least one part of the third carrier surface area.

[0082] The third carrier surface area can be specified in any way as required, for example in such a way that it covers one or more separate parts of the carrier surface, and / or that it forms a single, continuous area or comprises at least two distinct areas separated from each other. The third carrier surface area can overlap at least partially with at least one part of the second carrier surface area.

[0083] In an exemplary embodiment, it is specified that

[0084] - the first cap layer comprises for each of the base particles a first coating surrounding the respective base particle to form respective first cap-base particles; and

[0085] - the first cap-base particles are bonded to the carrier or to the first carrier surface area.

[0086] Each of the first coatings can be specified in any way as required, for example in such a way that it has a thickness, to which the above explanations on the specification of the first cap layer apply analogously. Each of the first coatings can be formed in any way as required, for example by CVD, PVD, PLD, sputter deposition, electrodeposition, coprecipitation, reverse coprecipitation, Pechini methods, modified Pechini methods, sol-gel methods, modified solgel methods, molten salt synthesis, nebulised spray pyrolysis, or solvothermal synthesis.

[0087] In an exemplary embodiment, it is specified that the first cap-base particles are bonded to the second cap layer.

[0088] In an exemplary embodiment, it is specified that

[0089] - the carrier has a fourth carrier surface area that is free of first cap-base particles; and

[0090] - the second cap layer is at least partially arranged over and in electrically conductive connection with at least one part of the fourth carrier surface area.

[0091] The fourth carrier surface area can be specified in any way as required, for example in such a way that it covers one or more separate parts of the carrier surface, and / or that it forms a single, continuous area or comprises at least two distinct areas separated from each other.

[0092] In an exemplary embodiment, it is specified that

[0093] - the first cap layer comprises for each of the base particles a first coating surrounding the respective base particle to form respective first cap-base particles;

[0094] - the second cap layer comprises for each of the first cap-base particles a second coating surrounding the respective first cap-base particle to form respective second cap-base particles; and

[0095] - the second cap-base particles are bonded to the carrier or to the first carrier surface area.

[0096] Each of the first coatings can be specified in any way as required, for example in such a way that it has a thickness, to which the above explanations on the specification of the first cap layer apply analogously. Each of the first coatings can be formed in any way as required, for example by CVD, PVD, PLD, sputter deposition, electrodeposition, coprecipitation, reverse coprecipitation, Pechini methods, modified Pechini methods, sol-gel methods, modified solgel methods, molten salt synthesis, nebulised spray pyrolysis, or solvothermal synthesis. Each of the second coatings can be specified in any way as required, for example in such a way that it has a thickness, to which the above explanations on the specification of the second cap layer apply analogously. Each of the second coatings can be formed in any way as required, for example by CVD, PVD, PLD, sputter deposition, electrodeposition, coprecipitation, reverse coprecipitation, Pechini methods, modified Pechini methods, sol-gel methods, modified sol-gel methods, molten salt synthesis, nebulised spray pyrolysis, or solvothermal synthesis.

[0097] In an exemplary embodiment, it is specified that the first cap layer or the second cap layer, if present, forms an outer covering of the anode.

[0098] In an exemplary embodiment, it is specified that the carrier comprises a grid, a mesh, a fibre felt, a foil, a foam, a plate, a dense or non-porous sintered material and / or a porous sintered material.

[0099] In an exemplary embodiment of the third aspect, it is specified that the apparatus is designed as an alkaline electrolyser, an alkaline water electrolyser, a solid-oxide electrolyser, a solid-oxide water electrolyser, an alkaline anion exchange membrane electrolyser, an alkaline anion exchange membrane water electrolyser, a fuel cell, a solid-oxide fuel cell, an alkaline anion exchange membrane fuel cell, or a unitized reversible fuel cell.

[0100] The explanations relating to one of the aspects of the invention, in particular to individual features of this aspect, apply analogously to the other aspects of the invention.

[0101] If the term "about" or "approximately" or "essentially" is used in the context of the present disclosure in connection with values or values ranges or with properties or geometries, this is to be understood as a tolerance range which the skilled person considers to be customary in this field. In particular, when the term "approximately" or "about" is used in connection with values or values ranges, a tolerance range amounts to ±20 %, preferably ±10 % and more preferably ±5 %. Lower limits of values ranges can thus be undercut by 5 % to 20 %. Upper limits of values ranges can thus be exceeded by 5 % to 20 %. Insofar as different values ranges, for example preferred and further preferred values ranges, are specified in the present disclosure, the lower limits and the upper limits of the different values ranges can be combined with one another.

[0102] In the following, embodiments of the invention are explained in more detail by way of example with reference to the accompanying drawings. However, the individual features resulting therefrom are not limited to the individual embodiments, but can be connected and / or combined with individual features described further above and / or with individual features of other embodiments. The details in the drawings are to be interpreted as explanatory only, but not restrictive. The reference signs contained in the claims are not intended to limit the scope of protection of the invention in any way, but merely refer to the embodiments shown in the drawings. The drawings show in

[0103] FIG. 1 a cross-section of a first embodiment of an anode;

[0104] FIG. 2 a cross-section of a second embodiment of an anode;

[0105] FIG. 3 a cross-section of a third embodiment of an anode;

[0106] FIG. 4 a cross-section of a fourth embodiment of an anode;

[0107] FIG. 5 a cross-section of a fifth embodiment of an anode;

[0108] FIG. 6 a cross-section of a sixth embodiment of an anode;

[0109] FIG. 7 a cross-section of a seventh embodiment of an anode;

[0110] FIG. 8 a preferred embodiment of an apparatus comprising a preferred embodiment of an electrochemical cell;

[0111] FIG. 9 a diagram of the mass activities of a comparative anode and of two sample anodes according to the first embodiment;

[0112] FIG. 10 a diagram of the mass activities of the comparative anode and of two sample anodes according to the second embodiment;

[0113] FIG. 11 a diagram of the mass activities of the comparative anode and of two other sample anodes according to the second embodiment; and

[0114] FIG. 12 a diagram of the mass activities of the comparative anode and of the sample anodes, at a given overpotential.

[0115] In FIG. 1, a first embodiment of an anode 10 according to the invention is shown schematically, that forms, by way of example, an electrochemical anode 10 for use in a water electrolyser shown in FIG. 8. The anode 10 comprises a carrier 12 designed according to a preferred embodiment and having a first carrier surface area 12a, a base 14 designed according to a first embodiment and consisting of or formed by a base layer 14', and a first cap layer 16 designed according to a first embodiment.

[0116] The carrier 12 is formed as a plate and consists of a carrier material that is Nb:SrTiO3, wherein the mass fraction of Nb is about 0.5 %. Thus, the carrier material comprises an electrically conductive material.

[0117] The base layer 14' consists of a base material that comprises a first HEO. In this embodiment, the first HEO is La(Cro.2Mno.2Feo.2Coo.2Nio.2)03-6 and the base layer 14' has a thickness of 30 monolayers corresponding to about 12 nm. The first cap layer 16 consists of a first cap material that comprises a first metal oxide unequal to the first HEO. In this embodiment, the first metal oxide is LaCoO3and the first cap layer 16 has a thickness of 2 monolayers corresponding to about 0.8 nm. In a second embodiment of the first cap layer 16, the first cap layer 16 has a thickness of 4 monolayers corresponding to about 1.6 nm.

[0118] The first carrier surface area 12a covers the whole upper carrier surface, as shown in FIG. 1, and forms a single, continuous area. The base layer 14', and thus the base 14, is arranged between and in electrically conductive contact with the first carrier surface area 12a, and thus with the carrier 12, and the first cap layer 16.

[0119] In FIG. 2, a second embodiment of the anode 10 is shown schematically. This embodiment is similar to the first embodiment, so that especially the differences are explained in more detail below.

[0120] In this embodiment, the first cap layer 16 is designed according to a third embodiment that is similar to the first embodiment, so that especially the differences are explained in more detail below. In this embodiment, the first metal oxide is LaCrO3. In optional embodiments of the first cap layer 16, the first metal oxide respectively is LaMnO3, LaFeO3or LaNiO3.

[0121] The anode 10 additionally comprises a second cap layer 18 designed according to a first embodiment. The second cap layer 18 consists of a second cap material that comprises a second metal oxide unequal to the first metal oxide. In this embodiment, the second metal oxide is LaCoO3and the second cap layer 18 has a thickness of 2 monolayers corresponding to about 0.8 nm.

[0122] The first cap layer 16 is arranged between and in electrically conductive contact with the base layer 14', and thus with the base 14, and the second cap layer 18.

[0123] In FIG. 3, a third embodiment of the anode 10 is shown schematically. This embodiment is similar to the first embodiment, so that especially the differences are explained in more detail below.

[0124] In this embodiment, the first carrier surface area 12a covers many separate parts of the carrier surface, of which only three parts are shown in FIG. 3, and thus consists of or is formed by a respective number of distinct areas separated from each other. Further, the carrier 12 has a second carrier surface area 12b that is adjacent to the first carrier surface area 12a. Namely, the second carrier surface area 12b covers many separate parts of the carrier surface, of which only four parts are shown in FIG. 3, and thus consists of or is formed by a respective number of distinct areas separated from each other. On the one hand, the first cap layer 16 is partially arranged over and in electrically conductive contact with the second carrier surface area 12b. On the other hand, the first cap layer 16 is partially arranged over and in electrically conductive contact with the base particles 14", and thus the first cap layer 16 is partially arranged over and in indirect electrically conductive connection with the first carrier surface area 12a, because the electrically conductive connection is achieved via the intermediate base particles 14".

[0125] The base 14 is designed according to a second embodiment that is similar to the first embodiment, so that especially the differences are explained in more detail below. In this embodiment, the base 14 consists of or is formed by many base particles 14" consisting of the base material, of which only three base particles 14" are shown in FIG. 3. The base particles 14" are bonded to the first carrier surface 12a area and the first cap layer 16.

[0126] The carrier 12 has a third carrier surface area 12c that is free of base particles 14" and corresponds to or matches or overlaps the second carrier surface area 12b. On the one hand, the first cap layer 16 is partially arranged over and in electrically conductive contact with the third carrier surface area 12c. On the other hand, the first cap layer 16 is partially arranged over and in electrically conductive contact with the base particles 14", and thus the first cap layer 16 is partially arranged over and in indirect electrically conductive connection with the first carrier surface area 12a, because the electrically conductive connection is achieved via the intermediate base particles 14".

[0127] In FIG. 4, a fourth embodiment of the anode 10 is shown schematically. This embodiment is similar to the third embodiment, so that especially the differences are explained in more detail below.

[0128] In this embodiment, the first cap layer 16 is designed according to its third embodiment and the anode 10 additionally comprises a second cap layer 18 designed according to its first embodiment. On the one hand, the first cap layer 16 is partially arranged between and in electrically conductive contact with the second, respectively third carrier surface area 12b, 12c and several parts of the second cap layer 18. On the other hand, the first cap layer 16 is partially arranged between and in electrically conductive contact with the base particles 14" and several other parts of the second cap layer 18, and thus the first cap layer 16 is partially arranged over and in indirect electrically conductive connection with the first carrier surface area 12a, because the electrically conductive connection is achieved via the intermediate base particles 14".

[0129] In FIG. 5, a fifth embodiment of the anode 10 is shown schematically. This embodiment is similar to the third embodiment, so that especially the differences are explained in more detail below.

[0130] In this embodiment, the first cap layer 16 is designed according to a fourth embodiment. This embodiment is similar to the first embodiment, so that especially the differences are explained in more detail below. In this embodiment, the first cap layer 16 comprises or provides for each of the base particles 14" a first coating surrounding the respective base particle 14" to form respective first cap-base particles 16'. The first cap-base particles 16' are bonded to the carrier 12 and especially to the first carrier surface area 12a.

[0131] The carrier 12 has a fourth carrier surface area 12d that is free of first cap-base particles 16' and that is adjacent to the second carrier surface area 12b. Namely, the fourth carrier surface area 12d covers many separate parts of the carrier surface, of which only four parts are shown in FIG. 5, and thus consists of or is formed by a respective number of distinct areas separated from each other.

[0132] In FIG. 6, a sixth embodiment of the anode 10 is shown schematically. This embodiment is similar to the fifth embodiment, so that especially the differences are explained in more detail below.

[0133] In this embodiment, the first cap layer 16 is designed according to a fifth embodiment. This embodiment is similar to the fourth embodiment, so that especially the differences are explained in more detail below. In this embodiment, the first metal oxide is LaCrO3. In optional embodiments of the first cap layer 16, the first metal oxide respectively is LaMnO3, LaFeO3or LaNiO3. In this embodiment, the anode 10 additionally comprises a second cap layer 18 designed according to its first embodiment. The second cap layer 18 is partially arranged over and in electrically conductive contact with the fourth carrier surface area 12d. On the one hand, the first cap layer 16 is partially arranged between and in electrically conductive contact with the second carrier surface area 12b and several parts of the second cap layer 18. On the other hand, the first cap layer 16 is partially, namely, with its upper parts above the respective base particles 14", arranged between and in electrically conductive contact with the base particles 14" and several other parts of the second cap layer 18, and the first cap layer 16 is partially, namely, with its lower parts beneath the respective base particles 14", arranged between and in electrically conductive contact with the base particles 14" and the first carrier surface area 12a. Thus, the first cap layer 16 is partially arranged over and in indirect electrically conductive connection with the first carrier surface area 12a, because the electrically conductive connection is achieved via the intermediate base particles 14" and the lower parts of the first cap layer 16, and the first cap layer 16 is partially arranged under and in indirect electrically conductive connection with said several other parts of the second cap layer 18, because the electrically conductive connection is achieved via the intermediate base particles 14" and the upper parts of the first cap layer 16.

[0134] In FIG. 7, a seventh embodiment of the anode 10 is shown schematically. This embodiment is similar to the sixth embodiment, so that especially the differences are explained in more detail below.

[0135] In this embodiment, the second cap layer 18 is designed according to a second embodiment. This embodiment is similar to the first embodiment, so that especially the differences are explained in more detail below. In this embodiment, the second cap layer 18 comprises or provides for each of the first cap-base particles 16' a second coating surrounding the respective first cap-base particle 16' to form respective second cap-base particles 18'. The second cap-base particles 18' are bonded to the carrier 12 and especially to the first carrier surface area 12a and the second carrier surface area 12b.

[0136] The first cap layer 16 is arranged between and in electrically conductive contact with the base particles 14" and the second cap layer 18. The first cap layer 16 is partially, namely, with its lower parts beneath the respective base particles 14", arranged between and in indirect electrically conductive contact with the base particles 14" and the first carrier surface area 12a. Thus, the first cap layer 16 is partially arranged over and in indirect electrically conductive connection with the first carrier surface area 12a, because the electrically conductive connection is achieved via the intermediate base particles 14", the lower parts of the first cap layer 16 and the lower parts of the second cap layer 18 that are beneath the respective base particles 14".

[0137] In FIG. 8, a preferred embodiment of an electrochemical cell 20 according to the invention is shown schematically. The cell 20 is constructed as well known in the art and comprises a cathode 22, an anode 10, an electrolyte 26, a diaphragm 28 and a vessel 30 holding the electrolyte 26. The cathode 22 is made of a Ni alloy as well known in the art. The anode 10 designed according to the first embodiment. The electrolyte 26 is of the alkaline type and consists of a solution of KOH as well known in the art. The diaphragm 28 is a foil made of Zirfon. The vessel 30 has two outlets for the oxygen produced at the anode 10 and hydrogen produced at the cathode 22, respectively.

[0138] In FIG. 8, also a preferred embodiment of an apparatus 32 according to the invention is shown schematically, that forms, by way of example, a water electrolyser. The apparatus 32 comprises the electrochemical cell 20, a voltage source 34 and two containers. The voltage source 34 is electrically connected to the cathode 22 and the anode 10. The containers are connected gas-tight to the outlets for collecting the produced gases.

[0139] In FIG. 9 to 12, test results of a comparative anode and of several sample anodes 10 are shown. The sample anode 10 and the comparative anodes were fabricated in a vacuum chamber by PLD on a plate-type carrier 12 of Nb:SrTiO3, the mass fraction of Nb being about 0.5 %. Before the PLD, the carriers 12 were etched with buffered hydrofluoric acid, followed by annealing in oxygen at 950 °C for 75 min in a furnace. During PLD, the laser fluence was 1.8 J / cm2at a frequency of 10 Hz. The oxygen pressure was 0.04 mbar, and the growth temperature was 650 °C. To perform electrochemical experiments, a custom-made adapter was employed to press the sample back side to the Pt plug of a rotating disk electrode, or RDE for short, provided by PINE RESEARCH INSTRUMENTATION, INC., USA. Several Pt connections of 50 nm length from the sample back side to the sample front side ensured electrical contact with the sample's carrier 12, base layer 14', first cap layer 16 and, if present, second cap layer 18. On the front side, a film area of 7.5 mm diameter was exposed to the electrolyte and sealed using a KALREZ O-ring, provided by ERIKS DEUTSCHLAND GMBH, Germany. The RDE shaft was rotating at 1600 rpm. Electrochemical testing was performed using a SP-300 potentiostat - provided by BIO-LOGIC SAS, France - at a cyclic voltammetry sweep rate of 10 mV / s, in a 150 ml alkaline-resistant Teflon cell, provided by PINE. The potentiostat was connected to the respective electrode to be tested, also referred to as working electrode, to a Hg / HgO reference electrode - provided by C3 PROZESS- UND ANALYSENTECHNIK, Germany - and to a counter electrode formed by a Pt wire. The potential E of the respective working electrode against the Hg / HgO reference electrode was measured in an electrolyte solution of 0.1 M KOH. The electrolyte was prepared by dissolving KOH pellets of 99.99 % purity - provided by SIGMA-ALDRICH - in deionized water. The electrolyte was O2-saturated prior to testing for about 20 min and maintained under an O2atmosphere during testing. The mass activities reported in the diagrams of FIG. 9 to 12 were measured at room temperature by averaging the backward and forward sweep of the 2nd cycle of the cyclic voltammetry measurement, and they are drawn in the unit "A / pgTM" over (E-IR) in the unit "V", i.e., over the difference between the potential E and the product of the electrical current I and the electrical resistance R between the working electrode and the reference electrode, the values of E, I and R having been output by the potentiostat. The index TM is short for "transition metal" and is to denote the transition metal(s) in the base 14 and, if present, in the first cap layer 16 and the second cap layer 18 of the respective working electrode. For example, TM refers to "Cr, Mn, Fe, Co and Ni" in case of the comparative and sample anodes #1 to #7 described below.

[0140] EXAMPLE 1

[0141] Example 1 was conducted with a comparative anode and two sample anodes 10 prepared according to the first embodiment of FIG. 1. The results of the respective mass activities are shown in FIG. 9.

[0142] Anode #1: This anode represents the comparative sample and consists of said plate-type carrier 12 and a base 14 formed as a base layer 14', the carrier and the base corresponding to those of the anode 10 according to the first embodiment of FIG. 1. Thus, the base layer 14' consists of a base material consisting of La(Cro.2Mno.2Fe0.2Coo.2Nio.2)03-5and has a thickness of 30 monolayers corresponding to about 12 nm.

[0143] Anode #2: This anode 10 is designed according to the first embodiment of FIG. 1 and comprises comparative anode #1 and in addition the first cap layer 16 according to the first embodiment. Thus, the first cap layer 16 consists of LaCoO3as the first cap material and has a thickness of 2 monolayers corresponding to about 0.8 nm.

[0144] Anode #3: This anode 10 is similar to sample anode #2. It is designed according to the first embodiment of FIG. 1 and comprises comparative anode #1 and in addition the first cap layer 16 according to the second embodiment. Thus, the first cap layer 16 consists of LaCoO3as the first cap material and has a thickness of 4 monolayers corresponding to about 1.6 nm.

[0145] The results show that the mass activities of both sample anodes #2 and #3 each comprising the first cap layer 16, are higher than that of comparative anode #1 without any cap layer. Sample anode #3 with 4 monolayers of the first cap material LaCoO3has a lower mass activity than sample anode #2 with only 2 monolayers.

[0146] EXAMPLE 2

[0147] Example 2 was conducted with the comparative anode #1 of example 1 and two sample anodes 10 prepared according to the second embodiment of FIG. 2. The results of the respective mass activities are shown in FIG. 10.

[0148] Anode #1: This comparative anode is the same as in example 1.

[0149] Anode #4: This anode 10 is designed according to the second embodiment of FIG. 2 and comprises comparative anode #1 and in addition the first cap layer 16 according to the third embodiment and the second cap layer 18 according to the first embodiment. Thus, the first cap layer 16 consists of LaCrO3as the first cap material and has a thickness of 2 monolayers corresponding to about 0.8 nm. And, the second cap layer 18 consists of LaCoO3as the second cap material and has a thickness of 2 monolayers corresponding to about 0.8 nm.

[0150] Anode #5: This anode 10 is similar to sample anode #4. It is designed according to the second embodiment of FIG. 2 and comprises comparative anode #1 and in addition the first cap layer 16 according to an optional embodiment other than the third embodiment and the second cap layer 18 according to the first embodiment. Thus, the second cap layer 18 consists of LaCoO3as the second cap material and has a thickness of 2 monolayers corresponding to about 0.8 nm. However, the first cap layer 16 consists of LaNiO3as the first cap material and has a thickness of 2 monolayers corresponding to about 0.8 nm.

[0151] The results show that the mass activities of both sample anodes #4 and #5 each comprising the first cap layer 16 and the second cap layer 18, are higher than that of comparative anode #1 without any cap layer. Both sample anodes #4 and #5 comprising the second cap layer 18 have a higher mass activity than sample anodes #2 and #3 without any second cap layer 18.

[0152] EXAMPLE 3

[0153] Example 3 was conducted with the comparative anode #1 of example 1 and two sample anodes 10 prepared according to the second embodiment of FIG. 2. The results of the respective mass activities are shown in FIG. 11.

[0154] Anode #1: This comparative anode is the same as in example 1.

[0155] Anode #6: This anode 10 is similar to sample anodes #4 and #5. It is designed according to the second embodiment of FIG. 2 and comprises comparative anode #1 and in addition the first cap layer 16 according to an optional embodiment other than the third embodiment and the second cap layer 18 according to the first embodiment. Thus, the second cap layer 18 consists of LaCoO3as the second cap material and has a thickness of 2 monolayers corresponding to about 0.8 nm. However, the first cap layer 16 consists of LaMnO3as the first cap material and has a thickness of 2 monolayers corresponding to about 0.8 nm.

[0156] Anode #7: This anode 10 is similar to sample anodes #4, #5 and #6. It is designed according to the second embodiment of FIG. 2 and comprises comparative anode #1 and in addition the first cap layer 16 according to an optional embodiment other than the third embodiment and the second cap layer 18 according to the first embodiment. Thus, the second cap layer 18 consists of LaCoO3as the second cap material and has a thickness of 2 monolayers corresponding to about 0.8 nm. However, the first cap layer 16 consists of LaFeO3as the first cap material and has a thickness of 2 monolayers corresponding to about 0.8 nm.

[0157] The results show that the mass activities of both sample anodes #6 and #7 each comprising the first cap layer 16 and the second cap layer 18, are higher than that of comparative anode #1 without any cap layer. Both sample anodes #6 and #7 comprising the second cap layer 18 have a higher mass activity than sample anodes #2 and #3 without any second cap layer 18. Both sample anodes #4 and #6 with LaCrO3or LaMnO3as the first cap material have a higher mass activity than sample anodes #5 and #7 with LaNiO3or LaFeO3as the first cap material.

[0158] EXAMPLE 4

[0159] FIG. 12 shows the mass activities of the sample anodes #2 to #7 and the comparative anode #1 mentioned above in Examples 1 to 3, measured at an overpotential q of 400 mV. The results show that higher mass activities are reached with the sample anodes 10.

[0160] LIST OF REFERENCE NUMBERS

[0161] 10 anode

[0162] 12 carrier

[0163] 12a / b / c / d first / second / third / fourth carrier surface area of 12

[0164] 14 base

[0165] 14' / 14" base layer / base particles

[0166] 16 first cap layer

[0167] 16' first cap-base particles

[0168] 18 second cap layer

[0169] 18' second cap-base particles

[0170] 20 electrochemical cell

[0171] 22 cathode

[0172] 24 electrolyte

[0173] 26 diaphragm

[0174] 28 vessel

[0175] 30 apparatus

[0176] 32 voltage source

Claims

CLAIMS1. Anode (10), comprising:- a carrier (12) having a first carrier surface area (12a) and consisting of a carrier material that comprises an electrically conductive material,- a base (14) consisting of a base material that comprises a first HEO, and- a first cap layer (16) consisting of a first cap material that comprises a first metal oxide; wherein- the base (14) is at least partially arranged between and in electrically conductive connection with at least one part of the first carrier surface area (12a) and at least one part of the first cap layer (16); and- the first HEO is unequal to the first metal oxide.

2. Anode (10) according to claim 1, wherein- the first metal oxide has a molecular formula of ABO3-Por BOX-P, with 0 < |3 < 1, 1 < x < 4, x G Q;- A, if present, is unequal to B and comprises at least one element selected from a group that comprisesCa, Sc, Ga, Sr, Y, Ba, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu; and- B comprises at least one element selected from a group that comprises Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Y, Zr, Nb, Mo, and Sn.

3. Anode (10) according to one or more of the preceding claims, comprising:- a second cap layer (18) consisting of a second cap material that comprises a second metal oxide; wherein- the first cap layer (16) is at least partially arranged between and in electrically conductive connection with at least one part of the base (14) and at least one part of the second cap layer (18); and- the second metal oxide is unequal to the first metal oxide.

4. Anode (10) according to claim 2, wherein- the second metal oxide has a molecular formula of CDO3-5or DOy-5, with 0 < 6 < 1, 1 < y < 4, y G Q;- C, if present, is unequal to D and comprises at least one element selected from a group that comprisesCa, Sc, Ga, Sr, Y, Ba, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu; and- D comprises at least one element selected from a group that comprises Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Y, Zr, Nb, Mo, and Sn.

5. Anode (10) according to one or more of the preceding claims, wherein- the first metal oxide is a second HEO; and / or- the second metal oxide, if present, is a third HEO.

6. Anode (10) according to one or more of the preceding claims, wherein- the first HEO, the second HEO, if present, and / or the third HEO, if present, has a molecular formula of KLO3-Xor LOZ-X, with 0 < X < l, l < z < 4, z G Q;- K, if present, comprises at least one element selected from a group that comprises Ca, Sc, Ga, Sr, Y, Ba, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu; and- L comprises at least four elements selected from a group that comprises Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Y, Zr, Nb, Mo, and Sn.

7. Anode (10) according to one or more of the preceding claims, wherein- the carrier (12) has a second carrier surface area (12b) that is adjacent to the first carrier surface area (12a); and- the first cap layer (16) is at least partially arranged over and in electrically conductive connection with the second carrier surface area (12b).

8. Anode (10) according to claim 6 and to claim 3, wherein- the first cap layer (16) is at least partially arranged between and in electrically conductive connection with the second carrier surface area (12b) and at least one partof the second cap layer (18).

9. Anode (10) according to one or more of the preceding claims, wherein- the base (14) comprises a base layer (14') consisting of the base material; and- the base layer (14') is arranged between and in electrically conductive connection with at least one part of the first carrier surface area (12a) and at least one part of the first cap layer (16).

10. Anode (10) according to one or more of the preceding claims, wherein- the base (14) comprises at least two base particles (14") consisting of the base material.

11. Anode (10) according to claim 10, wherein- the base particles (14") are bonded to the first carrier surface area (12a) and the first cap layer (16); and- the carrier (12) has a third carrier surface area (12c) that is free of base particles (14") and especially is adjacent to the first carrier surface area (12a); and- the first cap layer (16) is at least partially arranged over and in electrically conductive connection with at least one part of the third carrier surface area (12c).

12. Anode (10) according to claim 10, wherein- the first cap layer (16) comprises for each of the base particles (14") a first coating surrounding the respective base particle (14") to form respective first cap-base particles (16'); and- the first cap-base particles (16') are bonded to the carrier (12) or to the first carrier surface area (12a).

13. Anode (10) according to claim 11 and to claim 3, wherein- the first cap-base particles (16') are bonded to the second cap layer (18); and- the carrier (12) has a fourth carrier surface area (12d) that is free of first cap-base particles (16'); and- the second cap layer (18) is at least partially arranged over and in electrically conductive connection with at least one part of the fourth carrier surface area (12d).

14. Anode (10) according to claim 10 and to claim 3, wherein- the first cap layer (16) comprises for each of the base particles (14") a first coating surrounding the respective base particle (14") to form respective first cap-base particles (16');- the second cap layer (18) comprises for each of the first cap-base particles (16') a second coating surrounding the respective first cap-base particle (16') to form respective second cap-base particles (18'); and- the second cap-base particles (18') are bonded to the carrier (12) or to the first carrier surface area (12a).

15. Electrochemical cell (20), comprising:- a cathode (22), and- an anode (10) that is designed according to one or more of the claims 1 to 14.

16. Apparatus (32), comprising:- an electrochemical cell (20) that is designed according to claim 15.

17. Use of an anode (10) that is designed according to one or more of the claims 1 to 14,- as the anode in an electrochemical cell comprising a cathode and an anode or in an apparatus comprising a cathode and an anode;- in an alkaline electrolyser, an alkaline water electrolyser, a solid-oxide electrolyser, a solid-oxide water electrolyser, an alkaline anion exchange membrane electrolyser, an alkaline anion exchange membrane water electrolyser, a fuel cell, a solid-oxide fuel cell, an alkaline anion exchange membrane fuel cell, or a unitized reversible fuel cell; and / or- for electrolysis, water electrolysis, or for a recombination of hydrogen and oxygen.

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