Electrode and method for making the same

Abstract

The present invention relates to an electrode, preferably a gas evolution electrode, comprising a substrate, a porous interlayer and a catalytic layer, wherein the porous interlayer comprises nickel and have a surface area of at least 0. 1 m2 / g measured by BET, wherein the catalytic layer comprises at least one catalytically active metal, wherein said porous interlayer has an inner porous surface and an outer surface, wherein the at least one catalytically active metal is a transition metal, a rare earth element or a combination thereof, wherein at least 80% of said at least one catalytically active metal is deposited on the outer surface of said porous interlayer measured by cross-sectional SEM EDAX image analysis, wherein at most 20% of said at least one catalytically active metal is deposited in the inner porous surface measured by cross-sectional SEM EDAX image analysis.

Description

[0001] ELECTRODE AND METHOD FOR MAKING THE SAME

[0002] TECHNICAL FIELD

[0003] The present invention relates to an electrode , preferably a gas evolution electrode , a method for making the electrode and the use of such electrode in water electrolysis , preferably in alkaline water electrolysis .

[0004] PRIOR ART

[0005] Catalytically active Metal-based electrodes such as metal oxide electrodes are widely used in various electrochemical reactions both as anodes and cathodes due to their ef ficacy, stability, and long li fetime . Those kinds of electrodes are made of substrates such as plates or meshes coated with one or more catalytically active Metal .

[0006] Mixtures of several metals or their oxides can be appl ied on the substrate to form the catalytic layer . In the catalytic layer, catalytically active Metals catalyze targeted electrochemical reactions such as electrochlorination or water electrolysis . Some metal can be mixed with the precious metal to provide support or to minimi ze the corrosion during electrolysis .

[0007] Various techniques and modi fications have been adopted by the industry in order to improve the performance of the electrodes including :

[0008] - combining di f ferent metals from the same or di f ferent groups of the periodic table , doping the catalytic coating with small amounts of speci fic metals , - creating non-stoichiometric defects in the lattice of the catalysts ,

[0009] - increasing the porosity and the surface area of the catalytic coating,

[0010] -providing a porous interlayer to improve the conductivity and the robustness of the electrode . Elevated porosity and surface area of the interlayer are particularly critical to achieve good performance for some electrochemical reactions especially at high current .

[0011] A method used in the industry for making porous nickel- based interlayer involves applying nickel and aluminum on a substrate , then leaching aluminum leaving the porous nickel interlayer . Afterward, the catalytic layer i s deposited on the porous nickel-based interlayer via various methods to further improve the electrode activity . The maj or drawback of this method is that applying the catalytic layer on the porous nickel-based interlayer leads to the infiltration of the catalytic layer into the inner surfaces of the porous nickel-based interlayer and consequently, undesirable deposit of the catalytic layer is formed in the pores instead of the proper deposition on the outer surface of the porous nickel-based interlayer . This causes the reduction in ef ficiency of the catalytic layer due to the reduction of the surface area and due to the unavailability of the catalytic layer deposited in the pores .

[0012] Thus , it would be desirable to provide a method for making electrodes that can solve the aforementioned drawback without af fecting the performance or the li fetime of the electrodes . SUMMARY OF THE INVENTION

[0013] From what is stated above , the present application aims at providing an electrode , preferably gas evolution electrode and a method for making such electrode , which is mechanically stable and has a porous nickel-based interlayer, wherein a catalytic layer is mainly deposited on the surface of the porous nickel-based interlayer . This result is achieved using the method described in the appended claims , wherein the sacri ficial material i s removed from the interlayer after the step of applying the catalytic layer on the nickel-based interlayer, thereby obtaining a catalytic layer deposited on the outer surface of the porous nickel-based interlayer .

[0014] These and other obj ects and advantages of the present invention will become obvious from the following detailed description .

[0015] BRIEF DESCRIPTION OF THE FIGURES

[0016] Figure 1 shows a schematic representation of the method according to the comparative examples 1 and 3 .

[0017] Figure 2 shows a schematic representation of the method of examples 1 and 2 according to the present invention .

[0018] Figure 3 shows the SEM cross section images of the electrode of the method of the comparative example 1 . Figure 4 shows the plot of EDAX scan analysis of the electrode of the method of the comparative example 1 .

[0019] Figure 5 shows SEM cross section images of the electrode of example 1 according to the present invention . Figure 6 shows the plot of EDAX scan analysis of the electrode of example 1 according to the present invention . Figure 7 shows the single electrode potential for hydrogen evolution in alkaline media at 4 kA / m2of the electrode o f example 1 according to method of the present invention compared to the electrode of the comparative example 1 and the electrode of comparative example 2 .

[0020] Figure 8 shows the single electrode potential for oxygen evolution in alkaline media at 10 kA / m2of the electrode of example 2 according to method of the present invention compared to the electrode of the comparative example 3 .

[0021] Figure 9 shows a scheme for preparing an interlayer of the present invention using twin-wire arc spraying .

[0022] DETAILED DESCRIPTION OF THE INVENTION

[0023] For the purposes of the invention, definitions of some terms and / or expressions used in the present description and in the claims will be provided below .

[0024] A "nickel-based" substrate in the sense of the present invention is a substrate which is essentially made from nickel or from a nickel alloy . A "planar" substrate is a substrate which is substantially flat and essentially two- dimensional , i . e . a substrate which has dimensions in length and width which are much greater than the dimension perpendicular to the plane defined by its length and its width, i . e . its height or thickness . A " lamellar morphology" in the sense of the present invention refers to a coating comprising metallic patches and void patches which predominantly have larger dimensions parallel to the planar substrate than perpendicular to the planar substrate . In cross-sectional SEM ( scanning electron microscopy) images , a dimension parallel to the planar substrate can be considered as a diameter or length of the patch and a dimension perpendicular to the planar substrate can be considered as the height of the patch . In a maj ority of the metallic patches and void patches , the height of the patches is less than 30% , more preferably less than 20% of the diameter / length of the patch .

[0025] In the present patent application, all the operating conditions reported in the text must be understood as preferred conditions even i f not expressly declared .

[0026] For the purposes of the present discussion the term " to comprise" or " to include" also comprises the term " to consist in" or " essentially consisting of" .

[0027] For the purposes of the present invention, the definitions of the ranges always comprise the extreme values unless otherwise speci fied .

[0028] A first obj ect of the invention therefore relates to a method for making a gas evolution electrode , which comprises the sequential steps of : a - providing a substrate , b - depositing nickel or nickel-based material and at least one sacri ficial material on the substrate , thus obtaining an interlayer, c - depositing a catalytic layer compri sing at least one catalytically active metal on said interlayer, d - removing at least partially said at least one sacri ficial material from said interlayer such that the interlayer has a surface area of at least 0 . 1 m2 / g measured by BET while maintaining the at least one catalytically active metal and nickel in the interlayer substantially intact .

[0029] As mentioned, the core of the invention lies in that the sacri ficial material must be removed from the interlayer ( step d- ) after the step of applying the catalytic layer on the nickel-based interlayer ( step c ) . The method of the present invention allows to obtain an electrode , wherein the catalytic layer is mainly depos ited on the outer surface of the interlayer without being deposited into the pores of the interlayer . This is because the pores are formed after the deposition of the catalytic layer .

[0030] According to an embodiment , the at least one sacri ficial material is a polymer, which can be removed from the interlayer upon the exposure to an external stimulus . For instance , the polymer can be depolymeri zed, melted, or vapori zed when subj ected to heating or electromagnetic radiation . Alternatively, it can be dissolved using an appropriate solvent .

[0031] According to a preferred embodiment , said at least one sacri ficial material is a leachable metal , wherein said removing of step d- is a leaching treatment with a basic aqueous solution, wherein the catalytic layer is configured to allow the basic aqueous solution to infiltrate and leach out the leachable metal from the interlayer at least partly . It is not necessary that all leachable metals to be leached from the interlayer . The leaching has to create enough porosity such that the nickel-based interlayer has a surface area of at least 0 . 1 m2 / g measured by BET . Additionally, the catalytic layer formed on top of the interlayer might be highly porous to allow the basic aqueous solution to infiltrate and leach out the aluminum from the interlayer .

[0032] Advantageously, said at least one leachable metal is selected from the group consisting of aluminum, iron, zinc, magnesium, vanadium, rare earth elements , pre ferably aluminum . It is well known that those metals can be eas ily dissolved in basic solutions without af fecting nickel .

[0033] The porous nickel-leachable metal interlayer may be formed using a suitable thermal spraying process , such as flame spraying, wire-arc spraying, plasma spraying, cold spraying, high velocity oxyfuel (HVOF) spraying, high velocity air- fuel (HVAF) spraying, detonation gun and combustion wire spraying . Alternatively, it can be made using another type of surface finishing process , such as laser cladding and electroplating .

[0034] According to a preferred embodiment , the depositing of said nickel and said at least one leachable metal in step b- is a spray of said nickel and said at least one leachable metal , more preferably powder plasma spraying or electric wire-arc spraying of said nickel and said at least one leachable metal .

[0035] Step b- using spraying method then comprises :

[0036] - providing a first material comprising at least 50% , preferably at least 80% by weight nickel and a second material comprising at least 50% , preferably 80% by weight leachable metal ,

[0037] - depositing melted droplets from said first material and melted droplets from said second material on at least one side of said substrate .

[0038] The advantages of using thermal spray are the reduction in production costs and the increase in the electrode performance . The improvement in the electrode performance is associated to the increase in surface area and the increase in the robustness of the electrode . Additionally, the pores absorb the current reversal and therefore extend the li fe of the electrode .

[0039] Advantageously, the depositing of step c- is applying and thermal decomposing of at least one salt of the at least one catalytically active metal on the interlayer . The applying of the at least one salt of the at least one catalytically active metal may take place before the thermal decomposition, which leads to better adhesion of the metal on the interlayer .

[0040] Thermal decomposition produces highly porous catalytically active metal , which facilitates the infiltration of the basic aqueous solution and consequently the leaching of the leachable material from the interlayer . Salts of the catalytically active metals can be applied onto the interlayer ; the electrode can then be dried at temperatures between 60 and 120 ° C and then baked at high temperatures comprised between 350 and 650 ° C to oxidi ze the salts of catalytically active metals into metal oxides . Baking can alternatively be in the absence of oxygen to obtain the metallic or salt forms of the catalytically active metals . The application of a solution comprising the salts can be done in several repeating steps to increase the uni formity of the layer . A second obj ect of the invention relates to an electrode obtained according to the method of the present invention .

[0041] A third obj ect of the invention relates to a gas evolution electrode , preferably obtained according to the method of the present invention, which comprises a substrate , a porous interlayer and a catalytic layer , wherein the porous interlayer comprises nickel and has a surface area of at least 0 . 1 m2 / g measured by BET , wherein the catalytic layer comprises at least one catalytically active metal , wherein said porous interlayer has an inner porous surface and an outer surface , wherein the at least one catalytically active metal is a transition metal , a rare earth element or a combination thereof , wherein at least 80% of said at least one catalytically active metal is deposited on the outer surface of said porous interlayer measured by cross-sectional SEM EDAX image analysis , wherein at most 20% of said at least one catalytically active metal is deposited in the inner porous surface measured by cross-sectional SEM EDAX image analysis .

[0042] Preferably, at least 90% , more preferably at least 95% of said at least one catalytically active metal i s deposited on the outer surface of said porous interlayer measured by cross-sectional SEM EDAX image analysis , wherein at most 10% , more preferably at most 5% of said at least one catalytically active metal is deposited in the inner porous surface measured by cross-sectional SEM EDAX image analysis . In other words , the catalytic layer is deposited mainly on the outer surface of the interlayer . As can be seen from figure 6 , the SEM images show that at least 95% of the at least one catalytically active metal (praseodymium and iron) is deposited on the outer surface of the interlayer using the method of example 1 according to the invention . By comparison, figure 4 shows around 70% of the active metal is deposited on the outer surface of the interlayer while the rest 30% are deposited on the inner surface , i . e . the inner surfaces of the pores , using the method of the comparative example 1 . It is al so noted from both figures 4 and 6 that aluminum is not completely leached from both layers .

[0043] Advantageously, the catalytically active metal is obtained by applying and thermal decomposing of at least one salt of said at least one catalytically active metal . This is particularly advantageous for the reasons mentioned above .

[0044] According to a particularly preferred aspect , the interlayer exhibits a lamel lar morphology made from metallic patches and void patches , said metallic patches being made from a material selected from nickel , a low- alloy nickel component comprising at least 80 wt . % nickel or combinations thereof , wherein at least 50% of the metallic patches have a length o f at least 25 pm measured parallel to the planar substrate , wherein said void patches comprises said inner porous surface .

[0045] Preferably, the void ratio is within a range from 5 to 50% , preferably from 10 to 25% , wherein the void ratio refers to the ratio of void patches to the overall area o f a reference frame measured by cross-sectional SEM EDAX image analysis .

[0046] Patent application WO2023111223 Al , in the name o f the Applicant , describes a method for making nickel based porous layer using powder plasma spraying or electric wirearc spraying and describes the layer obtained from the method as having a lamellar morphology made from metallic patches and void patches as defined above . The unique properties of the interlayer made according to this method allows to obtain an electrode with high porosity and robustness . Patent application WO2023111223 Al i s incorporated herein by reference .

[0047] Thermal spray techniques are coating process in which melted ( or heated) materials are sprayed onto a surface . The " feedstock" ( coating precursor ) is heated by electrical (plasma or arc) or chemical means ( combustion flame ) . There are many techniques to produce this type of coating such as Twin Wires Arc Spraying ( TWA) where two metal wires are melted and then sprayed by compressed area onto the substrate (up to 2000g / min) . The use of one nickel wire and one aluminum wire allows the creation of a porous coating that increases its porosity once leaching ( loss of aluminum when there is contact of the coating with a strong base ) occurs .

[0048] Preferably, the at least one catalytically active metal is a transition metal , a rare earth element or a combination thereof . Preferably, the transition metal i s selected from a group consisting o f copper , iron, nickel , cobalt , tungsten, molybdenum, tin, manganese , or a combination thereof . Preferably, the rare earth element is selected from a group consisting of lanthanum, neodymium, cerium, praseodymium, or a combination thereof .

[0049] The at least one catalytically active metal may present in a form selected from a group consisting of free element , alloy, oxide , sulphide , hydroxide , and mixtures thereof . The load of the catalytically active metal may be comprised between 1 and 50 g / m2referred to metals .

[0050] In a preferred embodiment , the substrate is selected from a group selected from Ni , Fe, alloys of Ni or Fe , and mixtures comprising Ni or Fe . For instance , Ni wire woven mesh can be used . The interlayer and the catalytically active metal can be applied on both sides of the mesh .

[0051] According to a preferred aspect , the electrode is a cathode for alkaline water electrolysis , a cathode for chloralkali reaction or an anode for alkaline water electrolysis .

[0052] A fourth obj ect of the invention relates to an electrolyzer comprising one or more electrode according to the second or third obj ect of the invention .

[0053] A fi fth obj ect of the invention relates to the use o f the electrode according to the second or third obj ect of the invention in chlor-alkali reaction, anion exchange membrane water electrolysis , proton exchange membrane electrolysis , or alkaline water electrolysis .

[0054] The following embodiments are provided for illustrative purposes only of the present invention and must not be understood as limiting the scope of protection defined by the appended claims .

[0055] EXAMPLES

[0056] Example 1 according to the present invention

[0057] The Preparation of the electrode is done using a nickel mesh (Ni ) as a support . A porous interlayer of nickel and aluminum is formed on the substrate using electric wirearc spraying system which is schematically shown in Fig . 9 . The overall twin-wire arc spraying system is designated with reference sign 20 . A first metal wire 21 made from nickel ( or a nickel alloy such as N195AI 5 or N180AI20 ) and having a diameter of 1 . 6 mm is fed by first feeding rollers 22 through a first contact tube 23 which establishes an electrical contact between the first metal wire 21 and a positive pole 24 of an electric power supply . The contact tube 23 guides the first wire towards a contact zone 25 in front of a noz zle 26 through which a j et of atomi zing gas indicated by arrow 27 , for instance compressed air, is blown towards the contact zone 25 . A second wire 28 made from pure aluminum and also having a diameter of 1 . 6 mm i s fed by second feeding rollers 29 through a second contact tube 30 which establishes an electrical connection of the wire with the negative pole 31 of a power supply . The power supply provided a variable current between 120 A and 450 A at a variable voltage between 20V and 35V . In the contact zone 25 , the first and second wires 21 , 28 are not brought in actual physical contact which would result in a short circuiting of the power supply but in close proximity to each other so that an electric arc can form between the tip of the first wire 21 and the tip of the second wire 28. The electric arc melts the tip portions of the first and second wires 21, 28 and the atomizing gas 27, fed at a pressure between 2 bar (30 psi) and 5.5 bar (80 psi) , generates a spray jet 31 of molten droplets of the materials of the first wire 21 and of the second wire 23, respectively. The molten droplets impact on the nickel mesh substrate 11 arranged in the path of the molten droplets of the spray jet 31 and solidify forming an interlayer 12 comprising metallic nickel patches and metallic aluminum patches. The interlayer 12 exhibits an essentially lamellar structure of individual nickel patches and individual aluminum. Before leaching, the lamellar structures exhibited a volumetric aluminum content between 3 vol.% and 50 vol.% determined by image analysis of optical microscopy images or SEM images. The volumetric ratios of nickel and aluminum can, for instance, be controlled by selecting suitable feeding speeds of the first and second feeding rollers 22, 29, respectively and / or by selecting different diameters of the first and second wires 21, 28, respectively. However, even if, as in the present example, similar wire diameters and similar feeding speeds are employed, the volumetric aluminum content will generally be significantly lower than the volumetric nickel content because a significant portion of the aluminum will vaporize in the contact zone 25 and not form molten droplets at all.

[0058] Afterword, a solution containing praseodymium and iron salt is prepared and brushed on the interlayer. The precursor composition comprised 20,9 g of praseodymium (II) nitrate and 20,78 g of iron (II) / nitrate hexahydrate, brought to a volume of 100 mL with DI water. At this point, the electrode is first dried at temperatures of 80°C and then baked at 600°C under air for 10 min. The brushing, drying, and baking steps are repeated 5 times. A load of 40 g / m2of praseodymium is obtained.

[0059] As a final step an alkaline treatment is performed to remove aluminum present in the interlayer. 30% KOH solution is prepared, and the electrode is immersed for 20 minutes. It is to be noted that the active layer formed on top of the interlayer by means of thermal decomposition is porous enough to allow the alkaline media to infiltrate and leach out the aluminum from the interlayer, determining a final porosity with voids to nickel ratio between 5% and 50%. The resulting electrode is washed by means of DI water and is ready to be used as a cathode.

[0060] Example 2 according to the present invention

[0061] The synthesis of the electrode is done by using a nickel mesh (Ni expanded mesh of 0.8 mm thickness) and applying the same steps of example 1. A solution containing a cobalt salt and a nickel salt is prepared. The precursor composition comprised 19.77 g of nickel (IT) nitrate hexahydrate and 39.56 g of cobalt (II) / nitrate hexahydrate, brought to a volume of 100 mL with DI water.

[0062] Initially, the mesh with the interlayer is coated with the precursor composition and then heated in air in an oven at 500°C for 15 minutes. After cooling, the mesh was again coated with the precursor composition and again heated in the oven at 500°C for 15 minutes. The resulting catalytic layer contained 15 g / m2of Co. The cobalt resulting in the active composition may be a cobalt compound, such as a cobalt oxide, namely cobalt (IT) oxide (CoO) or cobalt (IT, ITT) oxide (Co304) , or nickel cobaltite (NiCo204) .

[0063] A final step of alkaline treatment similar to the one of example 1 is performed to remove aluminum present in the interlayer. The resulting electrode is washed by means of DI water and is ready to be used as an anode. Figure 2 summarizes the method of example 1 and example 2 according to the present invention.

[0064] Comparative example 1

[0065] The synthesis of the electrode of comparative example 1 is done in the same way as of the Example 1 according to the present invention, with a difference of leaching aluminum from the interlayer before applying the catalytically active layer of iron and praseodymium on the surface of the interlayer .

[0066] Comparative example 2

[0067] The synthesis of the electrode of comparative example 2 is done in the same way as of example 1 according to the present invention, with a di f ference of the absence of the interlayer, i . e . without applying the interlayer and the leaching of aluminum .

[0068] Comparative example 3

[0069] The synthesis of the electrode of comparative example 3 is done in the same way as of the example 2 according to the present invention, with a di f ference of leaching aluminum from the interlayer before applying the catalytical ly active layer of cobalt and nickel on the surface of the interlayer . Figure 1 represents the method according to the comparative example 1 and 3 . characteri zation studies

[0070] The following characteri zation studies were conducted . The electrode structures of example 1 according to the invention and comparative example 1 were studied at the SEM to veri fy the morphological appearance and to assure that the catalytic coating was depos ited on top of the interlayer . Figure 3 shows the SEM cross section images of the electrode of the method of the comparative example 1 . Figure 5 shows SEM cross section images of the electrode of example 1 according to the present invention . It i s clear that the outer catalyst layer can be distinguished from the porous intermediate layer in figure 5 . By contrast , the outer catalyst layer is immersed in the porous intermediate layer in figure 3 .

[0071] Figure 4 shows the plot of EDAX scan analysis of the electrode of the method of the comparative example 1 . Figure 6 shows the plot of EDAX scan analysis of the electrode of example 1 according to the present invention . As can be seen from figure 6 , the SEM images show that at least 95% of said at least one catalytically active metal is deposited on the outer surface of the interlayer us ing the method of example 1 according to the invention . By comparison, figure 4 shows less than 70% of the active metal is deposited on the outer surface of the interlayer while the rest are deposited on the inner surface , i . e . the inner surfaces of the pores using the method of the comparative example 1 .

[0072] The electrode activity was tested by means of a classical three electrodes setup for electrochemical characteri zation . A beaker cell was prepared with a solution of KOH at a concentration of 30% by weight and a temperature of 80 ° C . The electrode was welded to a nickel rod and placed in front of a counter electrode into the solution . A cathodic current of 10 kA / m2was applied for at least three hours and up to 60 hours to condition the electrode and successively the hydrogen evolution overpotential at di f ferent current density was determined by means of a reference electrode and a Luggin capillary . Figure 7 shows the single electrode potential for hydrogen evolution in alkaline media at 4 kA / m2of the electrode of example 1 according to method of the present invention compared to the electrode of the comparative example 1 and the electrode of the comparative example 2 . The electrode produced according to the method described in the invention showed a much lower hydrogen evolution overpotential .

[0073] The stability of the electrodes of example 1 according to the invention, comparative example 1 and comparative example 2 were tested . As reported in figure 7 , several cyclic voltammetry cycles were applied to bring the electrode to anodic potential in order to accelerate its degradation due to potential fluctuations that can be present in an intermittently operated water electrolys is plant . The hydrogen evolution potential was determined after 5 , 10 , 15 , 20 and 25 cycles .

[0074] The electrode of example 1 according to the invention shows inferior degradation rate compared to the electrodes of comparative example 1 and comparative example 2 .

[0075] Moreover, the stability of the electrode of example 1 according to the invention was tested by the application of a cathodic current of 30kA / m2for 1500 hours . The hydrogen evolution overpotential was determined as constant after the application of the protocol .

[0076] Similar to figure 7 , figure 8 shows the single electrode potential for oxygen evolution in alkaline media at 10 kA / m2of the electrode of example 2 prepared according to method of the present invention compared to the electrode of the comparative example 3 . The electrode produced according to the method described in the invention showed a much lower oxygen evolution overpotential .

Claims

CLAIMS1 . Gas evolution electrode , comprising a substrate , a porous interlayer and a catalytic layer, wherein the porous interlayer comprises nickel and has a surface area of at least 0 . 1 m2 / g measured by BET , wherein the catalytic layer comprises at least one catalytically active metal , wherein said porous interlayer has an inner porous surface and an outer surface , wherein the at least one catalytically active metal is a transition metal , a rare earth element or a combination thereof , wherein at least 80% of said at least one catalytically active metal i s deposited on the outer surface of said porous interlayer measured by cross-sectional SEM EDAX image analysis , wherein at most 20% of said at least one catalytically active metal is deposited in the inner porous surface measured by cross-sectional SEM EDAX image analysis .2 . Electrode according to claim 1 , wherein at least 90% of said at least one catalytically active metal i s deposited on the outer surface of said porous interlayer and at most 10% of said at least one catalytically active metal is deposited in the inner porous surface measured by cross-sectional SEM EDAX image analysis .3 . Electrode according to claim 1 or 2 , wherein said catalytically active metal is obtained by applying and thermal decomposing at least one salt of said at least one catalytically active metal .4 . Electrode according to any one of the preceding claims , wherein said interlayer exhibits a lamellarmorphology made from metallic patches and void patches , said metallic patches being made from a material selected from nickel , a low-alloy nickel component comprising at least 80 wt . % nickel or combinations thereof , wherein at least 50% of the metallic patches have a length of at least 25 pm measured parallel to the planar substrate , wherein said void patches comprises said inner porous surface .5 . Electrode according to claim 4 , wherein said void ratio is within a range from 5 to 50% , preferably from 10 to 25% , wherein the void ratio refers to the ratio of void patches to the overall area of a reference frame measured by cross-sectional SEM EDAX image analysis .6 . Electrode according to any one of the preceding claims , wherein the transition metal is selected from a group consisting of copper, iron, nickel , cobalt , tungsten, molybdenum, tin, manganese , or a combination thereof , and the rare earth element is selected from a group consisting of lanthanum, neodymium, cerium, praseodymium, or a combination thereof .7 . Electrode according to any one of the preceding claims , wherein said at least one catalytically active metal present in a form selected from free element , alloy, oxide , sulphide , hydroxide , and mixtures thereof .8 . Electrode according to any one of the preceding claims , wherein the electrode is a cathode for alkaline water electrolysis , a cathode for chlor-alkali reaction or an anode for alkaline water electrolysis .9 . Method for making electrode according to any one of the preceding claims , which comprises the sequential steps of : a - providing a substrate , b - depositing nickel or nickel-based material and at least one sacri ficial material on the substrate , thus obtaining an interlayer, c - depositing a catalytic layer comprising at least one catalytically active metal on said interlayer, d - removing at least partially said at least one sacri ficial material from said interlayer such that the interlayer has a surface area of at least 0 . 1 m2 / g measured by BET , while maintaining the at least one catalytically active metal and nickel in the interlayer substantially intact .10 . Method for making an electrode according to claim9 , wherein said at least one sacri ficial material is a leachable metal , wherein said removing of step d- is a leaching treatment with a basic aqueous solution, wherein the catalytic layer is configured to allow the bas ic aqueous solution to infiltrate and leach out the leachable metal from the interlayer .11 . Method for making an electrode according to claim10 , wherein said at least one leachable metal is selected from a group consisting of aluminum, iron, zinc, magnesium, tin, vanadium, rare earth elements preferably aluminum .12 . Method for making an electrode according to any one of the preceding claims 10 or 11 , wherein said depositing of said nickel and said at least one leachable metal in step b- comprises :- providing a first material comprising at least 50% by weight nickel and a second material comprising at least 50% by weight leachable metal ,- depositing melted droplets from said first material and melted droplets from said second material on at least one side of said substrate .13 . Method for making an electrode according to any one of the preceding claims 9 to 12 , wherein said depositing of step c- is applying and thermal decomposing of at least one salt of said at least one catalytically active metal .14 . Electrolyzer comprising one or more electrode according to any one of the claims 1 to 8 .15 . Use of the electrode according to any one of the claims 1 to 8 in chlor-alkali reaction, anion exchange membrane water electrolysis , proton exchange membrane electrolysis , or alkaline water electrolysis .

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