Multiphase / multilayer coating, method for executing a multiphase / multilayer coating and uses thereof

Abstract

The present disclosure relates to a multiphase / multilayer coating, method for executing a multiphase / multilayer coating and uses thereof. The present disclosure relates to the field of advanced coatings for electrochemical applications, specifically methods and systems for enhancing the active surface area of electrodes; namely electrolysers. The coatings of the present disclosures were designed using line-of-sight deposition techniques, such as Physical Vapor Deposition (PVD), e.g. magnetron sputtering, to achieve unique structures that improve electrochemical performance.

Description

D E S C R I P T I O NMULTIPHASE / MULTILAYER COATING, METHOD FOR EXECUTING A MULTIPHASE / MULTILAYER COATI NG AND USES THEREOFTECHNICAL FIELD

[0001] The present disclosure relates to a multiphase / multilayer coating, method for executing a multiphase / multilayer coating and uses thereof.

[0002] The present disclosure relates to the field of advanced coatings for electrochemical applications, specifically methods and systems for enhancing the active surface area of electrodes; namely electrolysers. The coatings of the present disclosure were designed using line-of-sight deposition techniques, such as Physical Vapor Deposition (PVD), e.g. magnetron sputtering, to achieve unique structures that improve electrochemical performance.BACKGROUND

[0003] In the last few years, worldwide energy demand has been continuously increasing with a strong slope. Parallelly, increasing pressure from society is taken place for more sustainable and environment friendly energy, causing hydrogen to appear as a potential way to provide clean energy. This led to the observed ongoing and increasingly interest in the development of efficient and cost-effective methods for either hydrogen production or CO2 capturing. Both methods are based on an electrochemical reaction involving two electrodes, one cathode and one anode.

[0004] One of the most promising methods for hydrogen production is through the relatively simple process of water electrolysis. This method of water splitting to produce hydrogen, or oxygen, is considered clean, efficient and sustainable due to water being the only molecule in the start and end of the hydrogen cycle, releasing energy and reproducing water at the same time. As with any chemical reaction, a certain amount of energy is required to "trigger" either the hydrogen evolution reaction (HER) or the oxygen evolution reaction (OER) from water, called overpotential, meaning that, to improve the efficiency of the process, one has tominimize the overpotential. The same principle works for CO2 capturing, as the process also occurs through the water electrolysis process.

[0005] The main prevailing solution used to minimize the overpotential is to use catalysts based on platinum and their derivatives which come with an extremely high cost, not to mention their few and scarce reserves on earth which heavily restricts their application to produce hydrogen in a sufficient scale for global energy demands.

[0006] Furthermore, a substantial effort has been made in research in the development of electrocatalysts using advanced nanomaterials with a particular focus on lower cost materials based on transition metals (TMs), transition metal oxides (TMOs), carbides (TMCs), nitrides (TMNs), phosphides (TMPs), dichalcogenides (TMDs), borides (TMBs), and metal-free (MF) composites. These advanced catalysts can be developed through different techniques and approaches. Recently, advanced solutions have been developed based on the exploitation of the synergetic effect of multiphases which optimize the catalytic efficiency. With this approach, the intrinsic activity of each active site is increased which allied to the increase in the number of active sites, increasing active surface area, leading to the global improvement of the efficiency of the process.

[0007] Physical vapor deposition (PVD) methods are widely used for thin film coating applications where control over the film's structural and chemical properties is critical. Techniques like magnetron sputtering have found utility in various applications due to their ability to produce dense, adherent films on substrates.

[0008] For applications requiring high electrochemical activity, such as batteries, fuel cells, or catalytic electrodes, the surface area and active site availability of the electrode are critical to the performance. Increasing these characteristics without sacrificing coating stability remains a challenge.

[0009] Traditional PVD techniques, however, often produce coatings with limited surface area enhancement. Conventional methods, which primarily involve deposition at normal or near-normal incidence angles, result in coatings with limited porosity and morphology variation, thereby restricting the electrochemical active surface area.

[0010] Recent advancements have focused on tailoring the deposition parameters, such as pressure, substrate temperature, and angle of incidence, to induce desirable surface morphologies. However, existing techniques still lack effective control over biphase or multilayered porous structures that could further enhance active surface area and improve coating functionality.

[0011] In document EP2260531B1, it is disclosed an element being an electrode for an electrochemical cell, which comprises an electrically conductive substrate and an electrically conductive corrosion resistant coating comprising a multielement material, which coating is formed on and at least partially covering said conducting substrate, is disclosed. It is also disclosed a method in manufacturing of such electrode and a use of the multielement material for corrosion protection of an electrode for an electrochemical cell. The multielement material has a composition of at least one of a carbide or nitride described by the formula MqAyXz, where M is a transition metal or a combination of transition metals, A is a group A element or a combination of group A elements, X is carbon or nitrogen or both, and z and at least one of q and y are numbers above zero. The multielement material further comprises at least one nanocomposite comprising single elements, binary phases, ternary phases, quaternary phases or higher order phases based on the atomic elements in the corresponding MqAyXz compound.

[0012] In document CN106271179A, it is disclosed a deposition stick for a ZrBz-CrB? multiphase coating and a preparing method of the stick. 70wt% to 95wt% of Zr powder, Cr powder and B powder by mass percent and 5wt% to 30wt% of Si powder and Mn powder by mass percent are adopted as raw materials, and through high- energy ball grinding and sintering moulding, the deposition stick for the ZrBz-CrB? multiphase coating is obtained. Through reasonable design of components of the deposition stick, meanwhile in the ball grinding and sintering process, the phase composition of the powder is controlled, and the prepared deposition stick forms the ZrBz-CrB? multiphase coating during use; metallurgical bonding with a chromium zirconium copper point welding electrode base body can be achieved, the bonding strength of the coating and the chromium zirconium copper point welding electrodebase body is improved, and the service life of a chromium zirconium copper point welding galvanized steel sheet is further prolonged.

[0013] Existing techniques for increasing the active surface area typically involve post- deposition treatments, which add complexity and cost. Thus, there is a need for deposition techniques that inherently create coatings with enhanced surface morphologies and multiphase configurations to improve electrochemical performance.

[0014] These facts are disclosed in order to illustrate the technical problem addressed by the present disclosure.GENERAL DESCRIPTION

[0015] The present disclosure relates to a multiphase / multilayer coating, method for executing a multiphase / multilayer coating and uses thereof. Namely, coatings that surprisingly enhance the active surface area during the deposition process, by using grazing incidence angles during deposition, the solution of the present disclosure achieves tailored morphologies and multiphase structures that increase the number of electrochemical active sites, improving the electrochemical efficiency of a substrate.

[0016] The described technology relates to the field of surface engineering, disclosing also a method for tailoring the morphology and phase arrangement of electrode coatings deposited via line-of-sight techniques, such as physical vapor deposition (PVD), e.g. magnetron sputtering. The technology is particularly focused on the synergy between maximizing active surface area and distinct phase arrangements for improved electrochemical performance by applying an innovative deposition procedure based on depositing at specific substrate angles.

[0017] The disclosed technology is also related to the deposition method for coating a substrate, in particular a multilayer thin film coating that allow the achievement of specific structures which can effectively increase the exposed area and thus, increasing the efficiency in hydrogen production and / or CO2 capture. Through the use of a specific design configuration in the PVD process, thin films with open structures can be deposited. These open structures allow to increase the exposed active surface area that an electrolyte is in contact with. Therefore, an increase in the efficiency ofhydrogen production and / or CO2 capture is achieved. Moreover and indirectly, this technology can also significantly reduce the costs of the process by eliminating the use of the platinum element.

[0018] Thus, this technology is especially suited to be applied in the cathode and / or anode used during the electrocatalysis process to produce hydrogen and / or capture CO2, in order to increase the efficiency of this process. The technology is to be applied to all cases where the catalytic efficiency is optimized with the synergetic effect of more than one active phase, then relying on the number and extension of the interfaces between the active phases, i.e. increasing the surface active area. With the increase in the active surface area exposed to the electrolyte, either the hydrogen evolution reaction and the oxygen evolution reaction are favoured, instead of relying on the costly price of platinum, the benchmark electrodes currently. Another advantage of this technology is that this design is suitable for the deposition of practically every other element / compound which still allows the increase in the surface area while introducing low-cost elements instead of relying on the costly price of platinum to get good hydrogen production or capturing CO2 efficiencies. This makes the technology also to have the potential to effectively reduce the costs of the processes and be much more environmentally friendly.

[0019] Considering the prior art previously mentioned and known, there is a need for an innovative deposition approach that leverages the potential of grazing angles and sequential phase layering to create a coating structure with significantly enhanced surface area and electrochemical activity. That problem is now solved with the use of grazing incidence angles, which opens the way to manipulate the growth direction of deposited materials, allowing for unique morphologies and create complex multilayered and multi-phasic structures.

[0020] The present disclosure utilizes controlled deposition angles, particularly grazing incidence, to produce unique bi-phasic and multilayer structures. These designs create high densities of electrochemical active sites, leading to enhanced efficiency in electrochemical processes like hydrogen production.

[0021] An aspect of the disclosure comprises a multiphase / multilayer coating for improving the electrochemical efficiency of a substrate wherein saidmultiphase / multilayer coating is coated on a substrate; wherein said multiphase / multilayer comprises: at least a first coating layer deposited on a porous substrate by a first cathode; at least a second coating layer deposited on top of the first coating layer by a second cathode, in particular wherein the position of the second cathode leads to a deposition of the second coating layer with a grazing angle from 0° to 45° in relation to the first coating layer; wherein the second coating layer is unevenly distributed along the surface of the first coating layer resulting in the multiphase / multilayer coating with an increased active surface area.

[0022] Along this description, it is considered that an unevenly distributed coating layer is a not uniform distributed or randomly distributed coating layer.

[0023] In an embodiment, the grazing angle of the multiphase / multilayer coating ranges from 5° to 40°, preferably from 10° to 35°, more preferably from 15° to 30°.

[0024] In an embodiment, the first coating layer of the multiphase / multilayer coating is deposited on a porous substrate at a grazing angle.

[0025] In an embodiment, the first coating layer of the multiphase / multilayer coating is deposited uniformly along the porous substrate surface, in particular including the walls of the pores.

[0026] In an embodiment, the multiphase / multilayer coating comprises alternating layers of the first coating layer and the second coating layer, wherein each layer is deposited at a grazing angle, creating a zigzag configuration.

[0027] In an embodiment, the multiphase / multilayer coating comprises a bi-phasic structure comprising a homogeneous and discontinuous phase or a zigzag multilayer structure with alternating phases.

[0028] In an embodiment, the first coating layer and / or the second coating layer of the multiphase / multilayer coating comprises oblique columnar growth.

[0029] In an embodiment, the first coating layer and the second coating layer of the multiphase / multilayer coating comprises a material selected form a list consisting of transition metals and their oxides, nitrides, carbides, dichalcogenides, and their combinations thereof.

[0030] In an embodiment, the thickness of each coating layer of the multiphase / multilayer coating is below 5 pm, preferably ranging from 2 nm to 500 nm, more preferably from 50 nm to 150 nm.

[0031] In an embodiment, the porous substrate of the multiphase / multilayer coating is selected from a list consisting of carbon, platinum, a rare metal, a noble metal and their combinations thereof.

[0032] In an embodiment, the porous substrate of the multiphase / multilayer coating comprises the form of a fabric and / or a foam and / or a rough surface.

[0033] In an embodiment, the coating of the multiphase / multilayer coating is obtained through a plasma deposition method.

[0034] In an embodiment, the porous substrate of the multiphase / multilayer coating is in a fixed position.

[0035] In an embodiment, the porous substrate of the multiphase / multilayer coating alternates between two predefined positions.

[0036] It is also disclosed the use of the multiphase / multilayer coating for increasing the active surface area during hydrogen production and / or CO2 capture.

[0037] It is also disclosed the use of the multiphase / multilayer coating as enhancer of active surface area of electrodes in electrochemical applications.

[0038] It is also disclosed a cathode in an electrolysis cell comprising the multiphase / multilayer coating described.

[0039] It is also disclosed an anode in an electrolysis cell comprising the multiphase / multilayer coating described.

[0040] It is also disclosed a method for executing a multiphase / multilayer coating comprising the following steps: depositing a first coating layer on a porous substrate; depositing a second coating layer with a grazing incidence angle over the first coating layer for achieve an uneven distribution; wherein the deposition of the second coating layer is subsequent to the deposition of a first coating layer; optionally repeating the process to create multilayer configurations.

[0041] In an embodiment, the first coating layer obtained by the described method is homogeneously distributed over the substrate and the second coating layer is discontinuously deposited at a grazing incidence angle.

[0042] In an embodiment, the first coating layer obtained by the described method is deposited with a straight or substantially straight angle in relation to the porous substrate.

[0043] In an embodiment, the first coating layer obtained by the described method is deposited with a grazing incidence angle in relation to the porous substrate.

[0044] In an embodiment, the method comprises alternating layers of the first coating layer and the second coating layer, wherein each layer is deposited at a grazing angle.

[0045] In an embodiment, the deposition method is conducted via magnetron sputtering or plasma deposition processes.

[0046] The method of the present disclosure involves alternating layers or phases, each with distinct electrochemical properties. In one embodiment, a bi-phasic structure is created on a porous substrate. In another embodiment, a zigzag multilayer configuration is achieved by alternating deposition directions.

[0047] With the now disclosed technology, an increase of 250% on the active surface area results in an increase of 100% of the electrochemical efficiency, which is a surprising effect not achieved by the prior art.BRIEF DESCRIPTION OF THE DRAWINGS

[0048] The following figures provide preferred embodiments for illustrating the disclosure and should not be seen as limiting the scope of invention.

[0049] Figure 1: Schematic representation of an embodiment of a method for coating a substrate, in this case with the deposition of a bi-phasic structure using grazing angle incidence.

[0050] Figure 2: Photographic representation of an elemental map distribution of Mo deposited with a straight angle over the porous substrate.

[0051] Figure 3: Photographic representation of an elemental map distribution of W deposited with a grazing angle over the porous substrate.

[0052] Figure 4: Photographic representation of an elemental map distribution of W and W deposited with a grazing configuration over the porous substrate.

[0053] Figure 5: Schematic representation of a two-step deposition method of a biphasic structure resulting in a zigzag configuration.

[0054] Figure 6: Schematic representation of a zigzag configuration deposited by magnetron sputtering.

[0055] Figure 7: Graphic representation of overpotential plots of different coatings deposited with different configurations and designs.

[0056] Figure 8: Schematic representation of an embodiment for a sputtering process to obtain a multiphase / multilayer coating.

[0057] Figure 9: Schematic representation of an embodiment for a sputtering process to obtain a multiphase / multilayer coating.DETAILED DESCRIPTION

[0058] The present disclosure relates to a multiphase / multilayer coating, method for executing a multiphase / multilayer coating and uses thereof. Namely, the present disclosure relates to advanced coatings for electrochemical applications. More specifically, it concerns methods and systems for enhancing the active surface area of electrodes, such as those used in electrolysers.

[0059] The present disclosure provides a multiphase / multilayer coating method using line-of-sight deposition techniques to achieve coatings with tailored morphologies. The coating of the present disclosure increases the active surface area of electrodes, improving their performance in electrochemical applications.

[0060] An aspect of the disclosure comprises a multiphase / multilayer coating for improving the electrochemical efficiency of a substrate wherein said multiphase / multilayer coating is coated on a substrate; wherein said multiphase / multilayer comprises: at least a first coating layer deposited on a poroussubstrate by a first cathode; at least a second coating layer deposited on top of the first coating layer by a second cathode, in particular wherein the position of the second cathode leads to a deposition of the second coating layer with a grazing angle from 0° to 45° in relation to the first coating layer; wherein the second coating layer is unevenly distributed along the surface of the first coating layer resulting in the multiphase / multilayer coating with an increased active surface area.

[0061] The present disclosure leverages line-of-sight deposition techniques, such as PVD, e.g magnetron sputtering, to produce coatings with tailored morphologies. By controlling the angle of incidence of the depositing species, it is possible to design coatings with enhanced active surface areas for electrochemical application. The present disclosure is based on a design concept for achieving suitable morphologies and phases arrangement in a coating deposited by line-of-sight techniques as, for example, PVD (physical vapour deposition) and, in particular, magnetron sputtering, which effectively increase the active surface area of electrodes that can be in contact with an electrolyte. The concept is based on using grazing angles for the depositing species, in relation to the substrate during the deposition process, which allows to tailor coatings with different configurations and designs.

[0062] In an embodiment, one of the designs is based on the deposition of a bi-phasic structure in a porous substrate, as illustrated in Figure 1, where, in a first step, a homogenous coating, e.g. M0S2 coating illustrated in Figure 2, is deposited by keeping a straight angle in relation to the target, followed by the deposition, in a second step, of a discontinuous coating, a e.g W coating in Figure 3, by grazing angle incidence deposition which allows that this phase is unevenly distributed along the "walls" of the pores, creating a bi-phase material at the surface and, therefore, a high number of electrochemical active sites, if that is the case with these two phases. This uneven distribution of the phases is confirmed by the elemental map distribution of the elements in Figure 4.

[0063] In an embodiment, other design can apply, which is based on the deposition of a multilayer very porous film, formed by the alternating electrochemical active phases. The production of the porous film can be enhanced by grazing incidence deposition which, by inverting the grazing direction, allows, simultaneously, to increase the realsurface area, as a consequence of the zigzag morphology. In a first step, a layer of phase A, e.g. Cr, is deposited in conditions leading to very porous morphologies, e.g. very high discharge pressures and / or grazing incidence angles - see step 1 in Figure 5. In a second step, a second layer of phase B, e.g. Ti, is deposited over the first one. If grazing incidence is used, the columns of the deposited layer are oblique in relation to the normal, see step 2 in Figure 5. Therefore, if the direction of the grazing angle is inversed for the deposition of each layer of phases A and B, the obliquity will change as well as the orientation of the possible deposited columns. By repeating this procedure, a bi-phasic structure with a zigzag configuration of the coating can be obtained, as shown in Figure 6 for Cr and Ti.

[0064] In an embodiment, the deposition in both these configurations can allow to create multiphase coatings with increasing number of the contact active surface area exposed to the electrolyte. The effective increase of efficiency allowed with these innovative processing methodologies can be demonstrated with a bi-phase system of Cu-0 and Mo-S phases. As shown in the overpotential plots in Figure 7, when compared to reference coatings, it is possible to observe a clear decrease in the overpotential needed to produce hydrogen when using the inventions aforementioned. Effectively, a promising effect in lowering the overpotential needed to produce hydrogen could be achieved by using these methodologies.

[0065] The technology can be briefly described by 9 figures, where Figure 1 shows the schematic design of the deposition of a bi-phasic structure using grazing incidence angle; Figure 2 shows the elemental map distribution of an element, molybdenium as an example, deposited with a straight angle while Figure 3 shows the elemental map distribution for the other element, in an example, tungsten, deposited with a grazing angle where both should arise and give a coating similar to what was shown on Figure 1. Showing this is also Figure 4 where the composite elemental map of both the previous elements, Mo and W, is shown. Figure 5 shows the other possible configuration with the schematic design of the deposition of a bi-phasic structure in a zigzag configuration, while Figure 6 shows the type of structures that can be achieved.

[0066] Finally, Figure 7 shows some preliminary results obtained using both of the aforementioned configurations when compared to their homogeneous counterparts.As can be seen in this embodiment, the best performance was achieved with the Zig- Zag coating and the increase of the performance is a little better than the bi-phase coating, but much better than the usual homogeneous coating. The improvement in the performance is due to a higher real surface area or to the synergetic effect of both phases.

[0067] In figure 8, it is disclosed a schematic representation of an embodiment for a sputtering process to obtain a multiphase / multilayer coating, wherein the porous substrate is in a fixed position and the first and second cathodes comprise a grazing angle from each other within the range of 0° to 45°.

[0068] In figure 9, it is disclosed a schematic representation of an embodiment for a sputtering process to obtain a multiphase / multilayer coating, wherein the porous substrate alternates between two predefined position.

[0069] The term "comprising" whenever used in this document is intended to indicate the presence of stated features, integers, steps, components, but not to preclude the presence or addition of one or more other features, integers, steps, components or groups thereof.

[0070] The disclosure should not be seen in any way restricted to the embodiments described and a person with ordinary skill in the art will foresee many possibilities to modifications thereof. The above-described embodiments are combinable.

[0071] The following dependent claims further set out particular embodiments of the disclosure.

Claims

C L A I M S1. A multiphase / multilayer coating for improving the electrochemical efficiency of a substrate, in particular an electrochemical cell, wherein said multiphase / multilayer coating is coated on a substrate; wherein said multiphase / multilayer comprises: at least a first coating layer deposited on a porous substrate by a first cathode; at least a second coating layer deposited on top of the first coating layer by a second cathode; wherein the position of the second cathode leads to a deposition of the second coating layer with a grazing angle from 0° to 45° in relation to the first coating layer; wherein the second coating layer is unevenly distributed along the surface of the first coating layer resulting in the multiphase / multilayer coating with an increased active surface area.

2. The multiphase / multilayer coating according to the previous claim, wherein the grazing angle ranges from 5° to 40°, preferably from 10° to 35°, more preferably from 15° to 30°.

3. The multiphase / multilayer coating according to any of the previous claims, wherein the first coating layer is deposited on a porous substrate at a grazing angle.

4. The multiphase / multilayer coating according to any of the previous claims, wherein the first coating layer is deposited uniformly along the porous substrate surface, in particular including the walls of the pores.

5. The multiphase / multilayer coating according to any of the previous claims, comprising alternating layers of the first coating layer and the second coating layer, wherein each layer is deposited at a grazing angle, creating a zigzag configuration.

6. The multiphase / multilayer coating according to any of the previous claims, comprising a bi-phasic structure comprising a homogeneous and discontinuous phase or a zigzag multilayer structure with alternating phases.

7. The multiphase / multilayer coating according to any of the previous claims, wherein the first coating layer and / or the second coating layer comprises oblique columnar growth.

8. The multiphase / multilayer coating according to any of the previous claims, wherein the first coating layer and the second coating layer comprises a material selected form a list consisting of transition metals and their oxides, nitrides, carbides, dichalcogenides, and their combinations thereof.

9. The multiphase / multilayer coating according to any of the previous claims, wherein the thickness of each coating layer is below 5 pm, preferably ranging from 2 nm to 500 nm, more preferably from 50 nm to 150 nm.

10. The multiphase / multilayer coating according to any of the previous claims, wherein the porous substrate is selected from a list consisting of carbon, platinum, a rare metal, a noble metal and their combinations thereof.

11. The multiphase / multilayer coating according to any of the previous claims, wherein the porous substrate comprises the form of a fabric and / or a foam and / or a rough surface.

12. The multiphase / multilayer coating according to any of the previous claims, wherein the coating is obtained through a plasma deposition method.

13. The multiphase / multilayer coating according to any of the previous claims, wherein the porous substrate is in a fixed position.

14. The multiphase / multilayer coating according to any of the previous claims , wherein the porous substrate alternates between two predefined positions.

15. An electrochemical cell comprising multiphase / multilayer coating according to any of the previous claims.

16. Use of the multiphase / multilayer coating described in any of the previous claims for increasing the active surface area during hydrogen production and / or CO2 capture.

17. Use of the multiphase / multilayer coating described in any of the previous claims as enhancer of active surface area of electrodes in electrochemical applications.

18. A cathode in an electrolysis cell comprising the multiphase / multilayer coating described in any of the previous claims 1 to 15.

19. An anode in an electrolysis cell comprising the multiphase / multilayer coating described in any of the previous claims 1 to 15.

20. A method for executing a multiphase / multilayer coating described in any of the previous claims 1 to 15, comprising the following steps: depositing a first coating layer on a porous substrate; depositing a second coating layer with a grazing incidence angle over the first coating layer for achieve an uneven distribution; wherein the deposition of the second coating layer is subsequent to the deposition of a first coating layer; optionally repeating the process to create multilayer configurations.

21. The method according to the previous claim, wherein the first coating layer is homogeneously distributed over the substrate and the second coating layer is discontinuously deposited at a grazing incidence angle.

22. The method according to any of the previous claims 20 to 21, wherein the first coating layer is deposited with a straight or substantially straight angle in relation to the porous substrate.

23. The method according to any of the previous claims 20 to 22, wherein the first coating layer is deposited with a grazing incidence angle in relation to the porous substrate.

24. The method according to any of the previous claims 20 to 23, comprising alternating layers of the first coating layer and the second coating layer, wherein each layer is deposited at a grazing angle.

25. The method according to any of the previous claims 20 to 24, wherein the deposition is conducted via magnetron sputtering or plasma deposition processes.

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