A cathode for an electrolysis cell, an electrolysis cell, an electrolytic device, a method for preparing the cathode and use of carbon dioxide

Abstract

The present disclosure provides a cathode for an electrolysis cell, the cathode comprising metal alloy catalyst comprising Ag, Cu and / or AgCu alloy on a cathode support. The present disclosure also provides an electrolysis cell and an electrolytic device for reducing carbon dioxide to products, the electrolytic device comprising the electrolysis cell. The present disclosure also provides a method for reducing carbon dioxide to one or more products, and to use of carbon dioxide in the method. The present disclosure also provides a method for preparing a cathode. The present disclosure also provides use of carbon dioxide for selectively producing one or more products.

Description

Field of the application

[0001] The present application relates to a cathode for an electrolysis cell, to an electrolysis cell, and to an electrolytic device comprising the electrolysis cell. The present application also relates to a method for reducing carbon dioxide to products such as hydrocarbons, alcohols, carboxylic acids and / or to CO and to a method for preparing the cathode.Background

[0002] It has been generally recognized that CO 2 emissions causing global warming can be converted into useful products such as hydrocarbons or CO using CO 2 electrolytic devices. CO can be used as a reactant for example for Fischer-Tropsch synthesis to produce liquid hydrocarbons.

[0003] However, the prior art materials and methods have problems in the selectivity of electrochemical methods used for converting CO 2 to a desired product. Recent investigations have demonstrated that there is need for a higher control over the product distribution of electrochemical CO 2 conversion. There is also a need to provide efficient and controllable methods and devices for producing a variety of reaction products from CO 2 .Summary

[0004] In the present invention it was found out how to overcome drawbacks of prior art. It was found out how to control a cathode catalyst layer to influence the selectivity and / or the effectivity of the cathode in a controllable manner, especially in reactions comprising reducing carbon dioxide to hydrocarbons and / or CO. These effects could be achieved by adjusting the cathode catalyst layer and using a specific method for preparing a cathode and for example a corresponding gas diffusion electrode (GDE).

[0005] The present application provides a cathode for an electrolysis cell, the cathode comprising a catalyst layer comprising Ag, Cu and / or AgCu alloy on a cathode support.

[0006] The present application also provides an electrolysis cell comprising an anode, the cathode, and an ion exchange membrane between the anode and the cathode.

[0007] The present application also provides an electrolytic device for reducing carbon dioxide to one or more products, such as to hydrocarbons, alcohols, carboxylic acids and / or to CO, the electrolytic device comprising the electrolysis cell, and a power supply for providing electric current and / or potential to the electrolysis cell(s).

[0008] The present application also provides a method for reducing carbon dioxide to one or more products, such as to hydrocarbons, alcohols, carboxylic acids and / or to CO, the method comprising providing the electrolysis cell or the electrolytic device, providing a source of carbon dioxide, supplying the carbon dioxide to the electrolysis cell and / or to the electrolytic device, applying electric current and / or potential to the anode and the cathode to provide electrolysis to electrocatalytically reduce the carbon dioxide to generate products, and separating one or more of the generated products.

[0009] The present application also provides a method for preparing a cathode, the method comprising providing a cathode support, such as a gas diffusion layer, and providing a solution comprising Ag +< and / or Cu +< and / or Cu 2+< , and / or providing a dispersion comprising Ag, Cu and / or AgCu alloy nanoparticles, applying, such as electrodepositing, airbrushing and / or ultrasonic spray coating, the solution and / or the dispersion to the cathode support to form the catalyst layer comprising Ag, Cu and / or AgCu alloy nanoparticles on the cathode support to obtain the cathode.

[0010] The present application provides use of carbon dioxide for selectively producing one or more products, such as hydrocarbons, alcohols, carboxylic acids and / or CO, for example ethene, with the method.

[0011] The main embodiments are characterized in the independent claims. Various embodiments are disclosed in the dependent claims. The embodiments and examples recited in the claims and in the specification are mutually freely combinable unless otherwise explicitly stated.

[0012] The present methods and devices can be used for the selective conversion of CO 2 to C1 or C2 compounds, such as one or more of CO, H 2 CO, H 2 CO 2 , CH 3 OH, CH 4 , C 2 H 4 , CH 3 CH 2 OH, CH 3 COOH, C 2 H 6 , and (COOH) 2 . These may be obtained by using the present metal alloy cathode catalyst coatings in a CO 2 electrolytic device.

[0013] Devices comprising a membrane electrode assembly comprising the cathode can be activated and / or recovered with a simple, fast and effective electrolytic method producing a stable electrolysis cell.

[0014] The obtained reaction products can be used for a variety of purposes, such as fuels, reagents and the like. Different reaction products can be obtained by using specific cathodes or cathode materials. It is possible to easily modify an existing electrolytic device to obtain desired reaction products, for example by installing a suitable cathode. This enables production of different products from carbon dioxide without high investments in equipment or laborious modifications, so that a variety of operators can produce desired products according to their needs by using their existing device setups.Brief description of the figures

[0015] Figure 1 shows representative XRD pattens of Cu, Ag, and AgCu nanoparticle alloys. Patterns were obtained using a Cu Kα radiation source (λ = 0.154 nm). Figure 2 shows representative GC trace of silver (Ag) electrolytic device. Thermal Conductivity Detector (TCD) shows peaks corresponding to the detection of H 2 and CO products in the first 10 mins. The appearance of signals >10 min result from cleaning procedure applied to the TCD. Figure 3 shows representative GC trace of Copper (Cu) electrolytic device. Flame Ionisation Detector (FID) shows peaks evidencing formation of C1 and C2 products including methane, ethene and ethane. Additional, unidentified peaks are also detected at time >11 mins. Figure 4 shows representative activation procedure for a copper cathode GDE in an electrolysis cell. Figure 5 shows representative potential vs time run at 200 mAcm -2< for copper based cathode GDE in an electrolysis cell after activation procedure. Figure 6 shows representative activation procedure for silver based cathode GDE in an electrolysis cell. Figure 7 shows representative potential vs time run at 200 mAcm -2< for silver based cathode GDE in an electrolysis cell after activation procedure. Figure 8 shows representative activation procedure of AgCu-2 alloy based cathode GDE in an electrolysis cell. Figure 9 shows representative potential vs time performance at 200 mAcm -2< of AgCu-2 alloy based cathode GDE after activation procedure. Figure 10 shows representative stabilities of AgCu-1 and AgCu-2 alloy based cathode GDEs using the same mixture of Sustainion and Nafion ionomer. Both alloys were tested under the same constant current densities of 200 mAcm -2< . Figure 11 shows representative Faradaic efficiencies of AgCu-2 alloy based cathode GDE with mixed ionomer at 200 mAcm -2< . Figure 12 shows representative comparison of Faradaic efficiencies of Cu, Ag, AgCu-1 and AgCu-2 based cathode GDEs. Figure 13 demonstrates the influence of ionomer and ionomer mixtures on the Faradaic efficiencies of AgCu-1 and AgCu-2 alloy based cathodes GDE. Figure 14 shows an exemplary single cell electrolyzer configuration (14A), a cathode GDE structure (14B) and a setup comprising an electrolyzer connected to a power supply (14C). The legends are: 1. Cathode flow field plate, 2. Anode flow field plate, 3. Polymer Electrolyte Membrane, 4. Cathode gasket, 5. Anode gas diffusion electrode (GDE), 6. Cathode gas diffusion electrode (GDE), 7. Anode gasket, 8 / 9. Flow channels, 10. Inlet for catholyte, 11. Outlet for anolyte, 12. Outlet for catholyte and gaseous products, 13. Inlet for anolyte, 14. Cathode electrical connection point, 15. Anode electrical connection point. 16. Membrane electrode assembly (MEA), 17. GDE composition, 18. Macrofibrous layer, 19. Microporous layer, 20. Catalyst layer, 21. Electrolyzer, 22. Power supply, 23. Computer, and 24. Electrical wires. Detailed description

[0016] In this specification, percentage values, unless specifically indicated otherwise, are based on weight (w / w, by weight, or wt%). If any numerical ranges are provided, the ranges include also the upper and lower values. In specific examples the embodiments or examples specified with the open term "comprise" may be further limited with a closed term "consisting of". The diameters disclosed herein, such as particle size, unless specifically indicated otherwise, refer to the smallest diameter, and may be average diameter, which may be number-average diameter, and may be determined microscopically, such as by electron microscopy. Disclosed dimensions or other features may be measured by image analysis of microscope images, such as images from a field emission scanning electron microscope (FE-SEM), a transmission electron microscope (TEM), such as a cryogenic transmission electron microscope (CRYO-TEM), or an atomic force microscope (AFM). A suitable imaging software may be used to determine the dimensions or the other features. Particle size can be also determined by Dynamic Light Scattering (DLS), spICP-MS, and / or XRD.

[0017] The present disclosure relates to electrochemistry and heterogeneous catalysis. The present electrocatalysts can be used for electrochemical carbon dioxide reduction to C1 and C2 compounds or their combination, for example in a form of gas phase mixture or liquid phase solution.

[0018] The present electrocatalysts can be used in cathodes and electrolytic and / or electrochemical devices comprising such cathodes. The devices include electrolysis cells, which can be used for chemical conversions and processes utilizing the chemical conversions. The chemical conversions may comprise any known chemical or reaction pathways and / or processes, or they may be new and / or enhanced reactions and / or processes, for example more selective, more efficient, more versatile and / or the like.

[0019] The present devices, which may be defined as electrocatalytic devices, can be used in electrocatalytic methods. Electrocatalysis is a catalytic process involving oxidation and reduction reactions through direct transfer of electrons, which requires electrocatalysts to lower the overpotential of the reactions. Therefore, the present methods are electrocatalytic methods, which require electricity, catalyst and reagents, such as CO 2 and H 2 O.

[0020] Disclosed is an electrolysis cell, such as an electrolytic cell and / or an electrocatalytic cell, or a device, system or a device arrangement comprising such a cell or the cathode. An electrolysis cell converts electrical energy into chemical energy. The electrolysis cell may be included in a system or an arrangement, for example in a reactor assembly or in an electrolytic device.

[0021] The electrolysis cell comprises an anode and a cathode. The anode and the cathode are arranged in or as a cell, which may be placed or located in a container, which can receive gas and / or liquid, such as electrolyte in the form of gas and / or liquid, usually water vapor or aqueous liquid. The cell may be in a zero-gap configuration in a two compartment cell. In general, the anode operates to complete the redox reaction cycle by oxidation reaction of water resulting in oxygen (O 2 ) and carbon dioxide (CO 2 ) formation. The reduction of CO 2 occurs on the cathode via a series of proton-electron transfer processes preferably resulting in formation of the specific reaction product distribution.

[0022] The cell or a cell assembly may comprise a membrane electrode assembly comprising an anode and a cathode, preferably in form of a sheet. The electrodes may be gas diffusion electrodes. Between the anode and the cathode there may be an ion exchange membrane interposed, which may be a polymer electrolyte membrane (PEM). The polymer electrolyte membrane may refer to any types of suitable membranes, such as anion exchange membranes (AEM), cation exchange membranes (CEM) or bipolar exchange membranes (BPM).

[0023] The membrane electrode assembly may be interposed between two fluid flow plates, i.e. flow field plates, having one or more, such as a plurality of channels, for reactant. The channels may be formed in or on the surfaces of the fluid flow plates on the side facing the electrodes, i.e. the channels may be open faced channels. Such a structure may be used in devices such as electrolytic devices and the like.

[0024] The electrolysis cell may have a casing, a frame or a body, including one or more inlets and one or more outlets for liquids and / or gases, and connections for a source of electrical energy, i.e. electric current or electric power. The flow field plates may form the casing, the frame or the body or a part thereof. In most cases the cathode plate is formed of stainless steel and the anode plate is formed of titanium. The anode and the cathode, and / or the flow field plates, are connected or connectable to a source of electric current, such as an external source of electric current, for example a power source or a power supply, which may be controllable. Electric current, such as with desired and / or controlled voltage and / or current, may be applied to the anode and to the cathode, and / or to the flow field plates, to obtain electrochemical, such as electrolytic, reactions in the liquid in contact with the anode and the cathode. The flow field plates may be considered as part of the electrodes, or as the electrodes. The flow field plate may comprise one or more connections for electric energy, more particularly electricity. The connection may comprise one or more connectors for wiring, or apertures or the like receiving portions for the connectors and / or the wiring.

[0025] The flow field plate may comprise an electrically conductive portion. The flow field plate may be used in an electrode, such as in an anode and / or a cathode, in an electrolysis cell, and in an electrolytic device. The flow field plate may be also called as a current collector plate. The flow field plate comprises or is a planar structure, and it typically has two large surfaces, wherein at least one of the large surfaces comprises open faced channels. The flow field plates comprise sides, which have the shortest dimension of the plate and may define the thickness of the plate, such as the highest thickness.

[0026] In applications relating to electrolytic devices and the like devices comprising two or more, such as a plurality, of electrolysis cells arranged as or in a stack, the flow field plates may be arranged in either bipolar and / or monopolar configuration.

[0027] One example provides an electrode comprising a flow field plate comprising an electrically conductive portion, and a gas diffusion cathode, wherein the flow field plate comprises one or more open faced channels, i.e. flow fields, on a surface of the flow field plate. The flow field plate may be configured or designed to receive the gas diffusion cathode. Open faced channels are open to the interior of an electrolysis cell when the flow field plate is installed in the cell. The open faced channels enable flow and contact of liquid and agents contained in the liquid, i.e. are in fluid and / or gas communication, with an electrode and for example with the catalytic portion of the cell, which may be in a form of a sheet.

[0028] The flow field plate may comprise one or more apertures for inlets and outlets, for example at the sides having the shortest width / thickness. Such apertures may be located on a side of a stack of cells or may be connected to the side of the stack, wherein connectors and / or tubes for incoming and outcoming liquid and / or gases may be connected to the apertures or other receiving parts. In or inside the plates the apertures may be connected to the channels. The one or more channels may be therefore connected from one end to an inlet and from other end to an outlet thus allowing circulation of liquid and / or gas through the electrode or cell.

[0029] The flow field plate may comprise one or more apertures for attaching to the other parts, such as for assembling the cell, for example with one or more screws, bolts, pins or the like attaching means. The parts of the cell may be sandwiched and preferably attached with the attaching means to obtain a cell. The cell may be designed as a single cell or as a stack of cells in bipolar and / or monopolar configuration, wherein the cells are preferably designed to fit each other i.e. they may have compatible sides and / or attaching portions, which allow the cells to be attached to each other.

[0030] Disclosed is an electrolytic device or device arrangement, such as an electrolyzer, comprising one or more of the electrolysis cells, such as comprising one or more gas-fed polymer electrolyte membrane electrolysis cells, or one or more devices comprising the cell(s), the cell comprising a membrane electrode assembly (MEA). The electrodes may be gas diffusion electrodes (GDE), which comprise a gas diffusion layer (GDL) and a catalyst layer (CL). The membrane electrode assembly comprises an anode GDE, a cathode GDE and a membrane between the anode and the cathode, which assembly is encased between an anode flow field plate and a cathode flow field plate.

[0031] In most cases the electrolysis cell comprises an anode, such as a gas diffusion anode, comprising or combined with a flow field plate, and / or a cathode, such as a gas diffusion cathode, comprising or combined with a flow field plate, and an ion exchange membrane between the anode and the cathode. The flow field plate, in the anode and / or in the cathode, may comprise one or more open faced channels on a surface of the flow field plate. The electrodes are in contact with a corresponding flow field plate, such as a cathode 6 is combined with a corresponding cathode flow field plate 1 so that the channels 8 of the cathode flow field plate are in fluid and / or gas communication with the cathode 1 (Fig. 2A). In analogous manner the anode 5 is combined with a corresponding anode flow field plate 2.

[0032] There are several MEA configurations. Preferred configurations include 5-layer systems, where two catalyst layers (one for anode and one for the cathode) are attached to two gas diffusion electrodes (GDEs) and sandwiched between one polymer electrolyte membrane (PEM) resulting in a total of 5 layers. Another configuration includes 3-layer configuration which is essentially the same as the 5-layer but without the two gas diffusion layers (GDLs) and instead the catalyst layers are directly coated on either side of the PEM.

[0033] An electrolytic device in general is a device that uses electricity to split water and / or other components into their constituent elements through electrolysis. An electrolytic device as described herein refers to a device setup comprising parts and / or components required to operate the device, including the electrolysis cell(s) and any required other parts and / or components, such as inlets and outlets, and any operating and / or controlling parts and / or components. An electrolytic device may comprise a plurality of electrolysis cells or cell assemblies arranged as a stack, for example wherein the electrolysis cells are flow cells arranged as one or more stack(s). A plurality may refer to two or more, five or more, ten or more, up to hundreds of cells, for example to 2-500, 2-10, 10-500, 10-100 or 10-50. An electrolytic device may comprise the electrolysis cell stack(s), pumps, valves, storage tanks, a power supply, a separator, one or more sensors, and / or other operating components. Electrolysis occurs within the cell stacks when an electric current is applied in the system across the electrolytes. The cells in a stack may be connected to the electric current in parallel and / or in series. Bipolar plates cannot be connected only in parallel. The electrolytic device described herein may be also called as an electrolyzer, or an electrocatalytic device.

[0034] The electrolyzer may be a gas-fed electrolyzer, at least for the cathode side, and it may comprise one or more gas-fed polymer electrolyte membrane electrolysis cells. The anode side may use a liquid anolyte / electrolyte. The gas may comprise CO 2 , such as humidified CO 2 gas, or any other applicable gas, such as inert gas. The electrolyzer may be a CO 2 electrolyzer.

[0035] The electrolyzer may be a zero-gap electrolyzer, such as a zero-gap CO 2 electrolyzer. Similarly, the electrolysis cell may be a zero-gap electrolysis cell. A zero-gap electrolyzer, or a zero-gap electrolysis cell, has no gap between the cathodes, anodes and the polymer electrolyte membrane (PEM). A zero-cap two-compartment electrolyzer or cell can be specifically used for CO 2 conversion to non-liquid products.

[0036] In zero-gap electrolyzers both catalyst layers in the cathode and anode GDEs are in direct contact on either side of the membrane. Zero-gap electrolyzer typically constitute in a 2-compartment electrolyzer. In "non zero-gap" electrolyzers at least one side of the membrane is in direct contact with the catalyst and other is separated by electrolyte. "Non zero-gap" typically constitute to 3-compartment electrolyzers.

[0037] The present cathode enables implementing the electrolytic device in the form of any applicable electrolytic device with any applicable structure. For example the electrolytic device may be a two-compartment electrolytic device or a three-compartment electrolytic device. A three-compartment electrolytic device may be used to maximize liquid hydrocarbon output. The electrolytic device may be a CO 2 electrolytic device.

[0038] The present disclosure provides an electrolysis cell, which may be an electrolytic device cell or a cell for an electrolytic device, the electrolysis cell comprising an anode, a cathode, and preferably an ion exchange membrane between the anode and the cathode, wherein the cathode is the cathode disclosed herein. Preferably the anode and the cathode are connected or connectable to a source of electric current, such as to a power supply for providing electric current to the electrolysis cells.

[0039] The electrolysis cell may be a flow cell. In a flow cell a flow of stream is arranged into the cell, such as a flow of liquid and / or a flow of gas. The flow may be continuous, in which case the cell is a continuous flow cell.

[0040] The present disclosure provides an electrolytic device for reducing carbon dioxide to hydrocarbons and / or to CO, the electrolytic device comprising one or more, such as a plurality of, for example two or more, the electrolysis cells disclosed herein, preferably arranged as a stack.

[0041] The device may comprise an inlet for reactant stream and / or feed, such as a source of carbon dioxide, and an outlet for reaction products, such as a stream and / or feed thereof.

[0042] The electrolytic device may be a continuous electrolytic device, which may be used for continuous electrolysis of carbon dioxide, preferably humidified carbon dioxide.

[0043] Preferably the device comprises two or more of the activated electrolysis cells. In such case the electrolysis cells may be flow cells arranged as one or more stack(s).

[0044] The electrolytic device, the electrolytic device system or the reactor assembly, which may be called as device, system and / or assembly, or a combination thereof, may comprise, be connected or be connectable to a power source or power supply. Any operating components may be operatively connected to controlling means, which enable the controlling means to control such as operate, the component(s). The electrolytic device, the electrolytic device system or the reactor assembly may be electronically controllable, thus comprising one or more controlling means, such as electronic control means, for controlling the operation of the electrolytic device. The controlling means may be or comprise one or more electronic control units, which may be programmable, comprising one or more processors, memory, and software configured, when executed with a processor in the control unit, to carry out one or more operations to implement the method. The control unit may be, comprise and / or be connected to a computer. The controlling means may be for example arranged to operate a power source or a power supply, for example to adjust the voltage, current, frequency, switching on and off and the like, and / or to adjust temperature, pressure and / or flow of liquids and / or gases by controlling and / or adjusting any of the operating components of the device, the system or the assembly, such as one or more pumps, valves, source of pressurized gas, actuators and / or the like, which may be operatively connected to the controlling means. The controlling means may be arranged to maintain one or more of said parameters in a desired range. The controlling means may be arranged, such as programmed, to monitor one or more properties from the device, the system, and / or the assembly, for example as a function of time, and as feedback to the monitored properties carry out one or more control actions in the device or the system to adjust the function of the device to carry out the present method and / or to maintain a property at a desired range and / or to a desired value.

[0045] In one example the electrolytic device comprises one or more, such as a plurality, for example two or more, of the electrolysis cells disclosed herein, preferably arranged as a stack, and a power source and / or a power supply and / or wherein the electrolytic device is connectable to a power source and / or a power supply.

[0046] The power supply or the power source is arranged to provide electric current to the anode and the cathode, or to the electrolysis cell(s). The electrolytic device may comprise connectors and / or wiring for the power source or the power supply. The power supply may refer to a device controlling the application of power and / or properties thereof, which usually converts electric current from a source to the correct voltage, current, and frequency to power the load. Power supply may be referred to as an electric power converter. The power supply may be controllable, for example by controlling means such as a control unit, to which it may be operatively connected, so that desired voltage and / or current may be obtained and provided to the anode and the cathode. The power timing, pulsing, frequency, and / or the like parameters may be also controlled. In one example the power supply comprises or is a potentiostat or a galvanostat, which may be used for controlling the present method and / or an activating method.

[0047] The electrolytic device may comprise flow control means, which may also be or comprise pressure control means, arranged to control flow and / or pressure in the electrolytic device and / or in the electrolysis cells. The flow control means may be operatively connected to controlling means. The flow control means may include one or more sensors for detecting flow and / or pressure in a cell or the electrolytic device / reactor, such as gaseous flow and / or pressure and / or liquid flow and / or pressure, which sensors may be connected to controlling means. The controlling means may be arranged, as feedback to the detected pressure, to control one or more devices and / or parameters to adjust the pressure in a desired range. For example, the electrolytic device may comprise one or more means for adjusting the pressure, such as one or more pumps, valves, sources of pressure, actuators, and / or the like, which may be operatively connected to the controlling means.

[0048] The cathode and optionally also the anode may comprise a catalyst layer on a support. The cathode may comprise a catalyst layer on a cathode support and the anode may comprise a catalyst layer on an anode support, such as a thin layer of catalyst material disposed on their major surfaces at the interface with the interposed membrane. The catalyst may be different in the cathode and in the anode. In the present invention it was found out how to obtain suitable catalyst in the cathode to promote desired electrolytic reactions. The present cathode can be used with any suitable anode and in any suitable device, device arrangement and / or process.

[0049] The anode comprises anode support, which may comprise or be same material as the cathode support, or it may comprise or be different material. The support in general may be called an electrode support. The anode may or may not contain a catalyst on the anode support. If the anode comprises a catalyst, the catalyst may be different from the catalyst on the cathode support. The anode may be prepared by using the same or similar methods, however preferably from different materials.

[0050] In one example the cathode support and / or the anode support comprise porous material, preferably porous electrically conductive material, which may be in a sheet or a layer form, and which may have planar major surfaces, such as carbon fiber paper. The cathode support is preferably a cathode support layer and / or the anode support is preferably an anode support layer. A gas diffusion electrode can be obtained by using such a porous electrode support.

[0051] The cathode support and / or the anode support may be a gas diffusion layer (GDL), and the support may comprise two layers: a macrofibrous layer (a backing layer) and a microporous layer (MPL). The catalyst layer (CL) is applied and / or adhered to or is on the microporous layer.

[0052] The present electrode may be a gas diffusion electrode. A gas diffusion electrode (GDE) comprises a gas diffusion layer (GDL) and a catalyst layer (CL). The anode may be an anode comprising an anode catalyst layer deposited on a gas diffusion layer (an anode GDE). The cathode may be a cathode comprising a cathode catalyst layer deposited on a gas diffusion layer (a cathode GDE).

[0053] The anode may be based, or comprise, one or more suitable compounds, such as metal, metal oxides, mixed metal or mixed metal oxides of Ir, Ru, Rh, Pt, Ni, Fe, such as iridium, IrO 2 , NiFe, transition metals, and the like materials. Commercially available anode materials may be used in the present devices and methods.

[0054] Disclosed is a metal alloy catalyst, i.e. a mixture of metals, which metal alloy catalyst may be used in electrolytic applications, such as in a cathode. The metal alloy catalyst may comprise or be in a form of nanoparticles. The metal alloy catalyst may be obtained with the method disclosed herein.

[0055] The present disclosure provides a cathode for an electrolysis cell, the cathode comprising metal alloy catalyst in the form of nanoparticles on a cathode support. The present cathode is especially suitable for a CO 2 electrolytic device.

[0056] A catalyst may comprise one or more transition metals and / or alloys thereof. A catalyst may comprise one or more elements selected from the group consisting of V, Cr, Mn, Fe, Co, Ni, Cu, Sn, Zr, Nb, Mo, Ru, Rh, Pd, Ag, Cd, Hf, Ta, W, Re, Ir, Pt, Au, Hg, Al, Si, In, Tl, Pb, Bi, Sb, Te, U, Sm, Tb, La, Ce, and Nd. In the present case it was found advantageous to use copper in the catalyst, preferably in combination with silver.

[0057] In one embodiment the catalyst comprises Ag and Cu, preferably the catalyst is a metal alloy catalyst consisting of Ag and Cu. In such as the catalyst layer preferably does not contain other catalysts. It was found out that the combination of Ag and Cu enabled promoting the reactions towards formation of specific hydrocarbons, such as ethene. The selectivity of the reaction could be enhanced by providing the Ag and / or Cu in the form of nanoparticles. The selectivity may be 80% or more, such as 90% or more, even 95% or more. Selectivity data may be obtained using gas-chromatography whereby the products are analyzed with respect to known calibration standard gases. More specifically, the peak areas for each chromatographic peak (product) are compared with known calibration standards. These raw product values (%) can then be converted into other more meaningful data including overall product selectivity (%), Faradaic efficiency (FE, %) and energy efficiency (%). The high selectivity is of practical value only when the activity of the reaction in terms of the turn-over-frequency is sufficiently high, which was achieved with the present catalysts. This is the main concern with the electrocatalytic reduction of CO 2 to feedstock chemicals. The selectivity and the stability can be controlled by either tailoring the AgCu alloy ratios as demonstrated in the examples, and / or by altering the ionomer mixture.

[0058] Preferably the metal alloy catalyst comprises AgCu alloy, such as AgCu alloy nanoparticles. For the thermodynamically stable performance under electrochemical conditions, the AgCu composition of the nanoparticles may vary as follows: Ag(99-90 wt%)Cu(1-10 wt%), Ag(1-10 wt%)Cu(99-90 wt%) or Ag(1-5 wt%)Cu(99-95 wt%). In one example the Ag:Cu ratio is in the range of 1-10:99-90 (wt%), which was found to provide improved electrocatalytic performance, including stability and selectivity, especially in combination with ionomers and binders.

[0059] In one embodiment the metal alloy catalyst comprises phase-separated Ag / Cu alloy nanoparticles. Especially phase-separated AgCu alloy nanoparticles were experimentally confirmed to provide desired selectivity. These alloys could enhance the selectivity of the reactions towards formation of ethene. The selectivity was higher than the selectivity of corresponding metal catalyst comprising only Ag or Cu. For example, it was possible to convert 90 % or more, such as 95 % or more, of all the formed hydrocarbons into ethene.

[0060] X-ray photoelectron spectroscopy (XPS) and / or transmission electron microscopy with energy dispersive spectroscopy analysis (TEM-EDS) data can be used to confirm the phase-separated structure and to distinguish from non-phase-separated structure.

[0061] The present metal alloy catalysts are preferably obtained with the method disclosed herein, wherein the metal alloy nanoparticles are formed either directly on the cathode support or deposited from a nanoparticle catalyst containing ink solution or dispersion, or a combination of both. By "combination of both" it is meant that it is possible to deposit a first set of nanoparticles, such as by ink deposition, to obtain a first deposit, and subsequent deposit a second deposit, such as by depositing a second set of nanoparticles by electrodeposition on top of the first deposit. It was found out that nanoparticles formed on the cathode support were better suitable for cathodes for electrolysis cells and for devices comprising the cells, compared for example with preformed nanoparticles which would be combined with cathode support.

[0062] The nanoparticles may have an average particle diameter, such as number average particle diameter, in the range of 10-50 nm, such as 15-25 nm or 20-40 nm, determined microscopically. The average nanoparticle size can also be estimated by X-ray diffraction (XRD). The average crystallite size (D) can be estimated according to the Scherrer equation which correlates peak broadening to the average crystallite size: D = k λ / β cos θ , where β is the full width at half maximum (FWHM) of the diffraction peak after instrumental broadening correction and k is the shape factor for the average crystallite. β is calculated from β2 = βo2 - b2, where βo is the measured FWHM of the sample and b is the measured FWHM of a well crystallized material (LaB6, 99.5 %) to account for instrument broadening and k = 0.9 for powders, assuming spherical shape.

[0063] Nanoparticles can be characterized with suitable methods. XRD constitutes a primary method of characterization on nanoparticles and nanoparticle alloys synthesized and applied as electrocatalysts in the present electrolytic devices. Other characterization methods include electron microscopy (i.e. TEM), Fourier transformed infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and Inductively Coupled Plasma Mass Spectroscopy (ICP-MS). XRD analysis is used to confirm crystal data including, phase composition, crystal structure and size of the synthesized nanoparticles. In addition, XRD can be used to detect the presence of inorganic impurities. Figure 1 shows representative XRD pattens of individual Cu or Ag nanoparticles, as well as AgCu nanoparticle alloys, which could be identified and used for characterizing the nanoparticles.

[0064] The catalyst layer or the cathodes comprising thereof can be prepared by using two different approaches. The first comprises electrodeposition of metal ions directly onto the surface of a gas diffusion layer or other porous layer, such as a carbon fiber paper. The second approach requires two steps comprising first presynthesizing the nanoparticles or nanoparticle alloys and then forming a dispersion with the synthesized nanoparticles, and any ionomer / binder, carbon powder and / or appropriate solvent, that is deposited onto the gas diffusion layer or the other porous layer by airbrushing and / or spray coating and / or dried i.e. annealed and / or post-annealed. In one example the synthesis of the nanoparticles comprises providing individual Cu or Ag nanoparticles, preferably having a number average particle diameter disclosed herein, for example 20-100 nm, then introducing an alloying ion (Ag +< , Cu +< or Cu 2+< ) in a suitable medium, such as water or an aqueous solution or mixture, and applying a reducing agent, such as ethene glycol or hydrogen, and / or reducing conditions, such as at elevated temperature, for example at 60 °C or more, and / or at elevated pressure, to obtain the desired nanoparticle alloy. The ratio between the starting nanoparticle and the alloying ion determines the properties of the final nanoparticle alloy.

[0065] The carbon powder may comprise any suitable carbon powder, such as comprising carbon particles, for electrodes, such as carbon black, conductive carbon and / or the like, which can be used as a (catalyst) support and / or conductive material in the electrodes, such as in anodes and / or cathodes. One example of commercial carbon powder is Vulcan XC-72. The carbon powder may have an average (basic) particle size in nanometer range, such as in the range of 20-100 nm, such as 20-50 nm or 30-60 nm.

[0066] In one example the metal alloy catalyst is obtained by providing a support, providing a solution comprising Ag +< and / or Cu +< and / or Cu 2+< , and / or a dispersion comprising Ag, Cu and / or AgCu alloy nanoparticles and optionally ionomers, binders and / or carbon powder, and electrodepositing, airbrushing and / or (ultrasonic) spray coating the solution and / or the dispersion to the support to form a catalyst layer on the support, preferably the catalyst comprising metal alloy nanoparticles, such as a catalyst layer comprising Ag, Cu and / or AgCu alloy nanoparticles.

[0067] A method for preparing a cathode may comprise providing a cathode support, which may be pretreated, providing a solution comprising Ag +< and / or Cu +< and / or Cu 2+< , and / or providing a dispersion comprising Ag, Cu and / or AgCu alloy nanoparticles, and electrodepositing, airbrushing and / or (ultrasonic) spray coating the solution and / or dispersion to the cathode support to form a catalyst layer on the cathode support, preferably the catalyst comprising metal alloy nanoparticles, such as to form a catalyst layer comprising Ag, Cu and / or AgCu alloy nanoparticles, to obtain the cathode. The cathode may be the cathode disclosed herein.

[0068] In one embodiment the method for preparing a cathode comprises providing a cathode support, providing a solution comprising metal ions, such as a solution comprising Ag +< and / or Cu +< and / or Cu 2+< , and electrodepositing the solution to the cathode support to form metal alloy nanoparticles, such as to form a catalyst layer comprising the metal alloy nanoparticles on the cathode support.

[0069] The electrodeposition may be carried out by any suitable electrodeposition method. In one example electrodeposition comprises providing a gas diffusion layer or other porous layer, such as a carbon fiber paper, such as pretreated carbon fiber paper. The porous layer may comprise a macrofibrous layer and / or a microporous layer. The porous layer may be pretreated with concentrated nitric acid (HNO 3 ). More particularly, to prepare a substrate or a gas diffusion layer for electrodeposition a pre-treatment may be carried out to increase the hydrophilicity of the substrate, as typically the gas diffusion layer, such as a carbon paper, may contain PTFE (Teflon) coatings, such as 5 wt% or more, that are on the surface and make the carbon paper hydrophobic. Though the hydrophobicity is needed for gas diffusion properties of the GDL it can provide adverse effects when placed in aqueous electrodeposition / plating baths and can lead to poor deposition. To improve this some of the PTFE can be stripped off by using the nitric acid on the surface for short periods time, such as for 1-24 h. In case the substrate does not contain PTFE, the pre-treatment is not required.

[0070] The porous layer may be fixed to a substrate or holder, such as a glass substrate. This is to ensure that electrodeposition only occurs on the microporous layer and not on the macrofibrous backing. The substrate including the porous layer may be immersed into an electroplating solution comprising a mixture of metal ions comprising Cu 2+< or Cu +< and Ag +< . The pH of the solution may be adjusted by using acid, such as HCl or H 2 SO 4 . Additives such as complexing agents may also be used. These can be used to tune the morphology of the nanoparticles. The (micro)porous layer is subjected to electrodeposition, for example by using a two-electrode configuration comprising the porous layer as the working electrode and a counter electrode, such as a copper-based counter electrode. A current density of -15-25 mAcm -2< may be applied, such as at a constant mode or at a pulsed deposition mode, until the desired thickness / charge density is obtained. The resulting films may be washed, such as with deionized water, and annealed at an elevated temperature, such as at a temperature between 100-150 °C, for 30-120 minutes, such as for about 1 h.

[0071] The dispersion, which may be a solution, may comprise metal ions dispersed and / or soluble in a suitable liquid, such as aqueous liquid or organic solvent, for example water, or a suitable mixture of water and organic solvent, such as water and isopropanol. The dispersion may also comprise already formed and / or obtained nanoparticles, wherein the dispersion may be called as ink, and which may be used in methods such as airbrushing and ultrasonic spray coating system. The obtained nanoparticles comprise or consist of the metal alloy catalyst and / or the metal catalyst consists of the nanoparticles. The dispersion may or may not comprise an ionomer. If an ionomer is used, it can be added also at a different point, such as to a cathode support without a catalyst, and / or to a formed catalyst on the support.

[0072] The porous layer may comprise an ionomer and / or binder coating, or it may be uncoated. Ionomers and / or binders, may be added to the dispersion(s) to improve consistency and / or mechanical stability. They also improve electrical / ionic conductivity of catalyst layer as well as adherence to a gas diffusion layer or other porous layer, such as a carbon paper. Ionomers may also behave as co-catalysts for tuning CO 2 RR selectivity. Key difference between ionomer and binder is that ionomers facilitate ion transport whilst binders do not. Binders instead mostly act as a 'glue' to ensure that nanoparticles / active material is secured to the substrate. The binder may be ionomeric or non-ionomeric. The binder may be a polymeric binder, such as polytetrafluoroethylene (PTFE) or polyvinylidene fluoride. In the case of PTFE it also provides chemical and temperature stability.

[0073] The catalyst may further comprise one or more ionomers, which can modify the selectivity of the catalyzed electrochemical carbon dioxide reduction. The ionomer may be anionic or cationic, or a mixture thereof. Charge and hydrophobicity / hydrophilicity are important parameters of the ionomers. The ionomer provides effects related to charge transfer between the catalyst and the ionomer, which can for example weaken adsorption energy of a reaction product.

[0074] Examples of ionomers comprise imidazolium functionalized polystyrene, for example available as a commercial product Sustainion, or sulfonated polytetrafluoroethene, for example available as a commercial product Nafion or Teflon.

[0075] The airbrushing may be carried out by any suitable airbrushing method and / or equipment. Airbrushing is preferably used only in the case of preformed nanoparticles, but not in the case of electrodeposition. For small scale cells, such as having an electrode area of 250 cm 2< or less, an airbrush pen may be preferred whilst for larger scale, such as more than 250 cm 2< , an automated ultrasonic spray coating system may be preferred. Both methods use a carrier gas which can be air or an inert gas such as N 2 . The support, such as substrate, gas diffusion electrode or carbon paper, in which the deposition is applied to, may be heated at elevated temperature.

[0076] Alternatively, nanoparticles can be applied by using ultrasonic spray coating method, and also preferably only in the case of preformed nanoparticles. The ultrasonic spray coating may be carried out by using any suitable ultrasonic spray coating method and / or equipment. Both the airbrushing and the ultrasonic spray coating can be easily scaled up to coat large surface areas. The cathode support may be as discussed in previous, for example it may be pretreated, such as a pretreated carbon fiber paper.

[0077] In airbrushing or ultrasonic spray coating nanoparticles may be provided as a nanoparticle ink dispersion, which may be the dispersion disclosed herein. The nanoparticle ink dispersion may comprise 20-300 gL -1< of the nanoparticles, such as 50-200 gL -1< . The cathode may be weighted before and after coating to confirm and determined the catalyst loading.

[0078] In one embodiment method for preparing a cathode comprises providing a cathode support, providing a dispersion comprising the present catalytic nanoparticles, such as a dispersion comprising Ag, Cu and / or AgCu alloy nanoparticles, airbrushing or (ultrasonic) spray coating the dispersion to the cathode support to form a catalyst layer comprising metal alloy nanoparticles on the cathode support, such as a catalyst layer comprising Ag, Cu and / or AgCu alloy nanoparticles on the cathode support.

[0079] In one embodiment the Ag, Cu and / or AgCu alloy nanoparticles are oxidated nanoparticles, preferably surface-oxidated nanoparticles. The deposited, such as electrodeposited, catalyst films may be heat-treated in one or more heat treatment step, to induce surface oxidation, for example at 80 °C or more and / or at 100 °C or more, for example for 20 minutes.

[0080] In one embodiment the dispersion comprising Ag, Cu and / or AgCu alloy nanoparticles comprises one or more of ionomers, binders and carbon powder. In one embodiment the catalyst layer comprising Ag, Cu and / or AgCu alloy nanoparticles comprises one or more of ionomers, binders and carbon powder.

[0081] In one example a cathode GDE comprises a catalyst layer comprising Ag, Cu or AgCu alloy nanoparticles and / or ionomer and / or carbon powder, on a gas diffusion layer support.

[0082] Figure 14A shows an example of a single cell electrolyzer. Figure 14B shows an example of a cathode gas diffusion electrode. Figure 14C shows an example of a setup comprising an electrolyzer connected to a power supply. The legends are: 1. Cathode flow field plate, 2. Anode flow field plate, 3. Polymer Electrolyte Membrane, 4. Cathode gasket, 5. Anode gas diffusion electrode (GDE), 6. Cathode gas diffusion electrode (GDE), 7. Anode gasket, 8 / 9. Flow channels, 10. Inlet for catholyte, 11. Outlet for anolyte, 12. Outlet for catholyte and gaseous products, 13. Inlet for anolyte, 14. Cathode electrical connection point, 15. Anode electrical connection point. 16. Membrane electrode assembly (MEA), 17. GDE composition, 18. Macrofibrous layer, 19. Microporous layer, 20. Catalyst layer, 21. Electrolyzer, 22. Power supply, 23. Computer, and 24. Electrical wires.

[0083] The portion of an electrolyte near the cathode, especially in a cell in which the cathode and anode are in separate compartments, may be called catholyte. Correspondingly the portion of an electrolyte near the anode, especially in a cell in which the cathode and anode are in separate compartments, may be called anolyte.

[0084] It was found out that the electrolysis cell or the electrolytic device comprising the electrolysis cell comprising the present cathode can be efficiently activated with a suitable method applying a (small) reverse current to the cell. This can be controlled by potential or by current. The reverse current is reverse to the current of the normal operation of the cell, i.e. to operational current, which comprises any suitable electrolytic method for obtaining one or more reaction products from the reactant. In the case of the reverse current, the flow of electrons is reversed so that the electrode that serves as a cathode during normal operation serves as an anode during application of reverse current, and the electrode that serves as an anode during normal operation serves as the cathode during application of reverse current.

[0085] With the activation method it is also possible to recover the performance of the electrolysis cell and / or an electrolytic device comprising the present cathode, which may have been operated for a certain period of time and wherein the performance thereof may have been decreased.

[0086] Disclosed is an electrochemical pre-conditioning and / or activating method that activates the electrolysis cell and reduces time required for an electrolyzer or the like electrolytic device to reach optimal and / or desired performance. The method is a simple and effective electrolytic method for activating CO 2 cells or electrolytic devices to achieve rapid initialization and subsequent stabilized performances. The method may also be a method for recovering the performance of the cell or the electrolytic device. The activation of the cell can be carried out by using a potentiostat, a galvanostat or other suitable controllable power supply.

[0087] The electrolysis cell, more particularly electrolysis flow cell, may be preconditioned with a current potential. A pre-conditioning method may comprise two linear sweep voltammograms (LSVs) whereby the first is initiated from the open circuit potential (OCP) to about +3.4 V, and used as a control, and the second (more critically) is carried out from a negative potential at about -2 V to about +3.4 V. The sweep rate is also an important parameter and is carried out at about 50 mVs -1< . The current reaches close to 200 mAcm -2< at 3.4 V.

[0088] The operation of the flow cell may be carried out by using a fixed current, such as applied at 100-400 mA / cm 2< , such as 150-250 mA / cm 2< . The voltage and / or the current may be measured at intervals, such as at 30-60 minutes intervals, such as 30-45 minutes intervals, for example about 40 minutes intervals. This may be carried out for a number of cycles, such as 2-6 cycles, for example four cycles.

[0089] The flow cell performs with a stable voltage, such as a voltage in the range of 2-6 V, such as in the range of 2 to 3.4-6 V, for example at about 3 V for the entirety of the measurement, such as for a total time of 160 min, with high selectivity for CO formation, which is generally above 95 %. Figure 7 shows potential vs time run at 200 mAcm -2< for silver based cathode GDE in an electrolysis cell after activation procedure. Table 2 shows representative data at 200 mAcm -2< for silver based cathode GDE in electrolysis cell after activation procedure.

[0090] One example provides a method for activating, stabilizing and / or recovering an electrolysis cell or a CO 2 electrolytic device, the method comprising providing an electrolysis cell or a CO 2 electrolytic device comprising one or more electrolysis cells, preferably comprising one or more electrolysis flow cells comprising a membrane electrode assembly, providing a power supply, such as a potentiostat, connected to the electrolysis cell(s) to activate the electrolytic cell, optionally flowing anolyte and catholyte through the electrolysis cell(s) prior to activation, for example for at least 5 or 10 minutes, such as for 10-30 minutes, operating the power supply while monitoring the current density, optionally measuring open circuit potential of the electrolysis cell(s).

[0091] An open circuit potential may be measured, such as until a stable result is obtained, for example for 60 seconds. The method may further comprise applying initial positive linear sweep voltammetry (LSV), preferably from open circuit potential, such as from the measured open circuit potential, preferably to obtain an increase in current density. The open circuit potential (OCP) is the potential of the cell when there is no current flowing through. The initial positive linear sweep voltammetry is a first linear sweep voltammetry. The initial positive linear sweep voltammetry may be applied / provided to a voltage in the range of 3.3-4.0 V, such as 3.3-3.8 V. In one example the initial positive linear sweep voltammetry is applied / provided to about 3.4 V. The initial positive linear sweep voltammetry may be ended when the target voltage is obtained and / or when the increase in current density is obtained.

[0092] The activation method comprises applying one or more activating reverse current treatments to the electrolysis cell, preferably to obtain an onset in current density, preferably until a target current density of 150 mAcm -2< or more at an operational cell potential is obtained. The activating reverse current treatment is applied subsequently to the initial positive linear sweep voltammetry, if carried out. The activating reverse current treatment may be applied to obtain an onset in current density, such as until a target current density of 150 mAcm -2< or more, preferably at an operational cell potential, such as at a typical operational cell potential, is obtained. The (typical) operational cell potential may be presented as a range and / or comprising one or more of the potential values or ranges thereof disclosed herein. For example, for the initial positive linear sweep voltammetry the operational cell potential may be from OCP to 3.4 V. For the activating reverse current treatment, the operational cell potential may be from -3 to +4 V, preferably from -2 to 3.4 V.

[0093] The target current density may be up to 700 mAcm -2< , such as up to 600 mAcm -2< or up to 500 mAcm -2< . However, it may be desired to use a lower upper target current density to protect the cell, such as 400 mAcm -2< or less, 300 mAcm -2< or less, 250 mAcm -2< or less, or preferably 230 mAcm -2< or less, such as 220 mAcm -2< or less. The target current density may be for example 170 mAcm -2< or more, 180 mAcm -2< or more or 190 mAcm -2< or more, for example in the range of 170-700 mAcm -2< , such as in the range of 180-220 mAcm -2< or any other combination of ranges of lower and upper values. This may be considered as a current density cut-off value or range.

[0094] The activating reverse current treatment may comprise applying a (second) linear sweep voltammetry to obtain an onset in current density, preferably at about 2.3 V, until a target current density of 150 mAcm -2< or more at an operational cell potential is obtained.

[0095] The current density cut-off ensures that current density does not exceed the desired limit (the target current density) and cause damage to the MEA. When current density exceeds the limit, the LSV may be (automatically) ended and the method may proceed to the next step.

[0096] The activating reverse current treatment may be applied / provided from about -2 to -1 V, such as from about -2 V, to about 2.9-4.0 V, or to about 3.0-4.0 V, such as to about 3.3-3.8 V. In one example the second sweep is applied / provided from about -2 V to about 3.4 V.

[0097] In one example the method comprises applying the initial positive linear sweep voltammetry (LSV) and / or applying the activating reverse current treatment with a sweep rate in the range of 40-100 mVs -1< , such as in the range of 40-70 mVs -1< , for example in the range of 40-60 mVs -1< , or about 50 mVs -1< . The sweep rate, i.e. how quickly the LSV's are performed, is an important parameter, as it was experimentally confirmed that the activation does not perform as well with lower sweep rates.

[0098] In one example the method comprises carrying out a performance test, such as monitoring stability of the cell, for example by applying a galvanostatic measurement, at the target current density, and / or by applying a constant / fixed current density. The electrolysis cell is supplied with a current from the power supply, such as about 1 A, to obtain a current density that may be any target current density disclosed herein, such as a current density of about 200 mAcm -2< , until the electrolysis cell performs at a stable potential, such as of about 3 V or about 3.0 V, or 3.2 V or another value as disclosed in the examples and / or a stable value in the range of 3.0-3.6 V, such as 3.0-3.3 V, for at least 100 minutes, such as for at least 200 minutes as shown in Figure 5, 7 and 9, determined by electrochemical voltage vs. time (chronopotentiometry) measurements. This indicates / identifies an activated electrolysis cell. The stability may be also monitored by electrochemical impedance spectroscopy (EIS) Nyquist plots at the target current density. The stable potential refers to maintaining the same or substantially the same voltage value, such as within a tolerance or variation of 2 % or less, 1 % or less, or 0.5 % or less, during the time period. The stable potential indicates that the cell is activated with the present method and / or that the cell passes quality control. The performance test may be carried to evaluate the quality of the activated cell, and / or to confirm that the activation was successful.

[0099] A potentiostat is a control and measuring device comprising an electric circuit, which controls the potential across the cell by sensing changes in its resistance, varying accordingly the current supplied to the system. A higher resistance will result in a decreased current, while a lower resistance will result in an increased current, in order to keep the voltage constant as described by Ohm's law.

[0100] One example provides an electrolysis cell for reducing carbon dioxide to products, such as to hydrocarbons and / or to CO, the electrolysis cell comprising a membrane electrode assembly comprising an anode, a cathode, and an ion exchange membrane between the anode and the cathode, wherein the electrolysis cell has been activated with the method.

[0101] One example provides a CO 2 electrolytic device for reducing carbon dioxide to products, such as to hydrocarbons and / or to CO, the electrolytic device comprising one or more activated electrolysis cells, preferably two or more, such as wherein the electrolysis cells are flow cells arranged as one or more stack(s), an inlet for reactant stream and / or feed, such as a source of carbon dioxide, an outlet for reaction products, such as a stream and / or feed of generated hydrocarbons and / or CO.

[0102] One example provides an activated electrolysis cell or a CO 2 electrolytic device showing stable potential of about 3 V for at least 100 minutes for a silver (Ag) based electrolyser, such as for at least 200 minutes, determined by electrochemical impedance spectroscopy (EIS) Nyquist plots or determined by electrochemical voltage vs. time measurements.Methods of use

[0103] The present electrolysis cells and electrolytic devices are intended to be used in one or more electrocatalytic methods or other methods including converting reactant to one or more products. These methods are considered as the normal operation of the electrolysis cells and / or the electrolytic devices. For example, a normal operation may comprise providing carbon dioxide, or other suitable reactant, to the cathode of the electrolysis cell and / or the electrolytic device, and applying electrical current to the cell or the device to produce an operating electrical potential between the cathode and the anode to reduce the reactant and to provide reaction products, such as one or more disclosed herein. The electrical current used in the normal operation may be called forward current. A reverse current may be used in activation or regeneration methods. Regeneration is needed when the cell or the electrolytic device is performed for an amount of time and the performance diverts from optimum, i.e. the cell performance depletes, which can be seen as a gradual increase in potential, for example up to 4.0 V. An ideal and / or general rate of depletion is in the range between 10-25 µVh -1< , which corresponds to 0.2-0.4 V in 2 years.

[0104] The electrolysis cell, the reactor assembly or the electrolytic device may be designed and / or configured to provide or feed carbon dioxide i.e. the catholyte, to the cathode and / or water or other aqueous solution, such as a solution comprising one or more electrolytes i.e. the anolyte, to the anode. Both the catholyte and the anolyte may be flowed through the cell, for example for about 5-30 minutes, such as 5-15 minutes before the actual reaction, and / or prior to activating.

[0105] The method may comprise either applying constant current density and measuring the potential, such as with galvanostatic / chronopotentiometry measurement, or applying a constant potential and measuring the current density, such as with potentiostatic chronoamperometry measurement. Both cannot be controlled at the same time. In examples used in experiments the galvanostatic mode was used.

[0106] After, and / or during, the carbon dioxide is provided to the electrolytic device and / or to the cell, electric current is applied to the electrolytic device. This may be carried out by using a fixed current, such as applied at 100-400 mA / cm 2< , such as 150-250 mA / cm 2< . A suitable voltage may be used, such as in the range of 0.5-3.0 V, such as 0.5-3.0 V. The electric current is provided for a suitable period of time to obtain desired reaction(s), preferably a desired degree of the reaction(s) and / or reaction products, such as conversion. For example, the actual conversion of CO 2 may be carried out for 30-180 minutes, such as 40-160 minutes, or continuously, preferably to obtain, detect and / or monitor desired reaction and / or reaction products.

[0107] The conversion of carbon dioxide in general may be mildly affected by the solvent, for example in the case of water as the solvent. However, with the present materials this effect can be compensated and diminished.

[0108] The reaction products comprise hydrocarbons and / or CO, which may be generated with the method disclosed herein. The generated reaction products may be separated by using any suitable method and / or device. The separated reaction products may be recovered and / or collected, which may be carried out by using any suitable method and / or device. The recovered and / or collected reaction products may be provided to further processing and / or further use, for example to be used as reagents for preparing further products, for example by Fischer-Tropsch synthesis to produce liquid hydrocarbons or used as fuel. The hydrocarbons and carbon monoxide can be used in a variety of applications, for example in industrial applications. Chemical industry uses carbon monoxide in the production of inorganic chemicals, such as metal carbonyls or titanium dioxide; organic chemicals, such as benzaldehyde and citric acid; and chemical intermediates such as toluene and diisocyanates, which are used to produce polyurethane. Carbon monoxide can be combined with other gases such as hydrogen, nitrogen, methane and carbon dioxide to provide a fuel gas, called syngas, which can be used as a feedstock chemical and as fuel. Carbon monoxide can be also used as a reducing agent in metals refining.

[0109] The present disclosure provides a method for converting, such as reducing, carbon dioxide to products, such as to hydrocarbons, alcohols, carboxylic acids and / or to CO, the method comprising providing the electrolysis cell or the electrolytic device, providing a source of carbon dioxide, supplying the carbon dioxide to the electrolytic device, applying electric current to the anode and the cathode to provide electrolysis to electrocatalytically reduce the carbon dioxide to generate hydrocarbons and / or CO, and separating the generated products, such as one or more of hydrocarbons, alcohols, carboxylic acids and CO.

[0110] The present disclosure provides a method for converting, such as selectively converting, carbon dioxide to ethene, the method comprising providing the electrolysis cell or the electrolytic device, providing a source of carbon dioxide, supplying the carbon dioxide to the electrolytic device, applying electric current to the anode and the cathode to provide electrolysis to electrocatalytically reduce the carbon dioxide to generate ethene, and separating the generated ethene.

[0111] Gas chromatography (GC) may be used to detect and analyze the gaseous product stream from the cell or the electrolyzer, such as shown in Figure 2. Gas chromatography can be used to analyze in real-time the product distribution of gaseous products from a performing electrolytic device. The peaks are calibrated using standard gas samples and the area under the peaks are integrated to give quantitative data. It is possible to also detect unknown products that have not been previously calibrated with standard gas samples.

[0112] Faradaic efficiencies can be calculated using the following equation: FE % = n x × n e − x × F / Q × 100 where n x is the amount of product x (mol) determined by gas chromatography (GC), n e-x is the number of electrons to make x from CO 2 / H 2 O, F is the Faraday constant (96,485 C mol -1< ) and Q is the total charge passed.

[0113] The method may comprise detecting the generated and / or separated product(s) and / or recovering the detected and / or separated product(s). The detection may be carried out by using any suitable methods, such as by gas chromatography, for example High Performance Liquid Chromatography (HPLC).

[0114] The source of carbon dioxide may be any suitable source which provides carbon dioxide in an amount and / or in a form that can be used and / or that can be modified into usable form and / or amount to be used in the present method. The source of carbon dioxide may comprise one or more containers, which may be equipped with controllable valves and / or actuators for controlling the flow of the carbon dioxide from the container.

[0115] The carbon dioxide, or a gas and / or solution comprising carbon dioxide, which may be called a reactant or a solution comprising the reactant comprising carbon dioxide, is provided, such as supplied, fed or conveyed, to the electrolytic device, especially to the cathode of the electrolytic device. The cathode and / or the electrolytic device may be in a cell or other container, which is arranged to receive the reactant or the solution comprising the reactant, in general in a suitable form, which may be liquid and / or gas. The reactant may be provided in an aqueous solution, such as in water, and / or in another solution, such as an electrolyte solution and / or a solution comprising organic solvent, or a combination of aqueous and organic solvents. In one example the reactant comprising carbon dioxide comprises carbonate and / or bicarbonate.

[0116] The reactant and / or the source of carbon dioxide may be provided in a suitable form, such as in the form of liquid, gas or a mixture of liquid and gas, such as humidified gas, which may be obtained by flowing gas through water, such as a water-bubbler. The reactant may comprise or be carbon dioxide. Carbon dioxide may be provided as carbon dioxide gas, and the gas may be mixed with liquid in the cell or the electrolytic device. The reactant comprising carbon dioxide and / or the source of carbon dioxide, or the catholyte, may comprise humidified CO 2 gas. No activating agents or other gaseous inlet streams, such as gaseous N 2 , are needed, or even desired. Any liquid may be provided from a source of liquid, which may comprise one or more containers, which may be equipped with controllable valves and / or actuators for controlling the flow of the liquid from the container.

[0117] The reactant to be provided to the anode, or the anolyte, may comprise one or more salts, such as KHCO 3 , for example in a concentration in a range of 5-50 mM, such as 5-15 mM, for example about 10 mM.

[0118] The methods disclosed herein are preferably carried out in absence of gaseous streams and / or flows, such as gaseous CO 2 or other gaseous streams and / or flows, such as gases and / or vapours of one or more of isopropanol, ethanol, ammonia, N 2 H 2 , HCl, sulphur dioxide and / or nitrous oxide, and / or in the absence of activating agents, such as alkali or alkali earth metal cations.

[0119] The carbon dioxide may be converted into one or more type of reaction products, i.e. compounds, including carbon monoxide, hydrocarbons and / or C x H y O z products, as well as H 2 and O 2 as byproducts. As the selectivity of the catalytic reaction can be controlled by using different catalytic coatings on the cathode, and optionally different cathodes, as well as controlling the reaction conditions, it is possible to obtain desired cathode reactions and / or desired reaction products, more particularly mainly the desired reaction products. The selectivity can be further controlled by controlling the reaction conditions and / or used reactants, such as by selecting a suitable source of carbon dioxide.

[0120] The hydrocarbons may comprise one or more of C1-C2 products. In the formula C x H y O z , x is a positive integer, such as 1, 2 or 3. Variables y and z are non-negative integers such as 0, 1 or 2 or, for example, 4, 5 or 6. Values of y and z may be equal, or they can be unequal such that y may be larger than z or alternatively y may be smaller than z.

[0121] The temperature of the cell or the electrolytic device, or the liquid in the cell and / or supplemented into the cell, especially during the conversion, may be controlled and adjusted to and / or maintained at a desired range. For example, the device may be a room temperature device, and the methods may be carried out at room temperature, wherein the temperature may be in the range of 20-25 °C. However, the temperature range may be wider, ranging up to 60 °C. The temperature may be controlled by temperature controlling means arranged in a cell or the electrolytic device, such as heating means and / or cooling means, which means may be operatively connected to controlling means.

[0122] In one embodiment the method is a method for reducing carbon dioxide to hydrocarbons comprising C1 hydrocarbons, C2 hydrocarbons or combination thereof, such as methane, ethene, and / or ethane.

[0123] In one embodiment the method is a method for reducing carbon dioxide to ethene. The selectivity to especially ethene was experimentally associated with a catalyst comprising a combination of Ag and Cu.

[0124] In one embodiment the method is a method for reducing carbon dioxide to CO. A selectivity to carbon monoxide was also experimentally confirmed and especially associated with Ag catalyst.

[0125] More particularly the method may be a method for reducing carbon dioxide selectively to one or more of said products. Other minor reactions may occur, but the carbon dioxide may be reduced to obtain selectively mainly said reaction product.

[0126] Disclosed is use of carbon dioxide for selectively preparing reaction products disclosed herein, such as the hydrocarbons and / or CO, with the methods and devices disclosed herein.Examples Example 1: X-ray Diffraction (XRD) Data

[0127] The data provided herein are representative characterization data based on powder X-ray diffraction (XRD) patterns of copper (Cu), Silver (Ag), and silver-copper (AgCu) nanoparticle alloys.

[0128] The XRD patterns of both the Cu and Ag nanoparticles corroborate as expected with the reference patterns and suggest good purity and the absence of any oxides. The AgCu nanoparticle alloy samples (examples AgCu-1 and AgCu-2) confirm the co-existence of both Cu and Ag peaks. Example 2 also confirms the presence of minor cuprous oxide (Cu 2 O), likely due to surface oxidation. Both examples of AgCu alloys are in agreement with literature observations for XRD pattens of AgCu alloys, for example as disclosed in ACS Appl. Mater. Interfaces 2017, 9, 29, 24711-24721.

[0129] Figure 1 shows representative XRD pattens of Cu, Ag, and AgCu nanoparticle alloys. Patterns were obtained using a Cu Kα radiation source (λ = 0.154 nm). The patterns were indexed to references according to JCPDS; Cu (01-070-3039), Ag (04-001-2617) and Cu 2 O (04-007-9767)Example 2: Gas Chromatography (GC) Data

[0130] The following data provided herein are representative data for the gaseous product analysis of electrolytic devices using gas chromatography.

[0131] Gas chromatography (GC) is used to analyze, in real-time, the product distribution of gaseous products from a performing electrolytic device. The peaks are calibrated using standard gas samples and the area under the peaks are integrated to give quantitative data.

[0132] Figure 2 shows representative GC Trace of silver (Ag) electrolytic device. Thermal Conductivity Detector (TCD) shows peaks corresponding to the detection of H 2 and CO products in the first 10 mins. The appearance of signals after 10 min result from cleaning procedure applied to the TCD.

[0133] Figure 3 shows representative GC trace of Copper (Cu) electrolytic device. Flame Ionisation Detector (FID) shows peaks evidencing formation of C1 and C2 products including methane, ethene or ethene and ethane. Additional, unidentified peaks are also detected at time >11 mins.Example 3: Electrodepositing catalysts on gas diffusion layers (GDL)

[0134] Pretreated carbon papers (5 cm 2< , conc. HNO 3 with or without 5 % PTFE coating) were fixed on to a glass substrate / holder. The substrates were submerged into electroplating solution consisting of mixture of metal ions of Cu 2+< and Ag +< , with pH adjusted using HCl or H 2 SO 4 to a desired pH. Electrodeposition was performed using a two-electrode configuration with the carbon paper as the working electrode and a copper based counter electrode. A current density of -20 mAcm -2< was applied until the desired thickness / charge density was obtained. The resulting films were rinsed with deionized water and annealed between 100-150 °C for 1 h.Example 4: Synthesis of AqCu-2 Alloy nanoparticles

[0135] Copper nanoparticles (20 nm, 1 g) were dispersed into ethylene glycol (250 mL) by ultrasonication. In a second container the alloying was prepared by dissolving silver nitrate (536 mg) in distilled water (10 mL). The silver nitrate solution was then added to the dispersed Cu nanoparticles and allowed to mix under reducing conditions for period of time. The resulting alloy was collected by centrifugation and washed with distilled water and dried at 60 °C.Example 5: Ink preparation for airbrush / ultrasonic spray coating

[0136] For a cell with 5 cm 2< electrode area 30 mg of nanoparticles, 1.5 mg carbon powder (Vulcan XC-72), and 32.5 µL ionomer solution (single or mixed ionomer, 5 wt%) were sonicated in an IPA / water solution and airbrushed onto a cut piece of GDL or carbon paper (Sigracet 39BB). The resulting GDE was annealed at 80 °C for 20 min and 120 °C for 20 min. For samples utilizing sustaining ionomer an additional soaking in 1 M KOH for 1 h was also carried out.

[0137] Ink preparation was scaled accordingly for larger samples. For samples with >250 cm 2< electrode area the ink was deposited using automated ultrasonic spray coating system.Example 6: Testing of the CO 2 electrolytic cell

[0138] The electrolyzer was assembled comprising of a membrane electrode assembly (MEA) comprising of the prepared cathode GDE, a Sustainion based membrane and an IrO 2 based anode GDE. The catholyte comprising of humidified CO 2 (30 mLs -1< ) and anolyte comprising of 10 mM KHCO 3 (3 mLs -1< were circulated / flowed through the electrolytic cell for 10 min prior to the activation procedure and subsequent performance testing. Testing was undertaking at room temperature. The potentiostat utilised was a Metrohm Autolab PGSTAT204 with a 10 A booster module or Metrohm VIONIC or similar. The booster increases the maximum current of the PGSTAT204 to 10 A and enables electrical impedance measurements. The activating treatments were carried under potentiostatic mode, which include a combination of positive and reverse sweeps.1. Activation of electrolytic cell

[0139] The first linear sweep voltammetry (LSV) comprises measuring the open circuit potential (OCP) for around 60 s and applying a positive potential sweep to around 3.4 V. The second linear sweep comprises of a reverse potential sweep from around -2 V to around 3.4 V until a current density of 150 mAcm -2< or more is achieved.2. Electrolytic cell performance testing

[0140] Following the activation procedure, the electrolytic cell was tested under galvanostatic mode at a constant current density of 200 mAcm -2< . The potential vs time response was measured at 40 min intervals for a total of four cycles. In each cycle, gas-chromatography samples were taken every 20 mins from the catholyte outlet. Additionally, electrical impedance spectra were acquired in between each cycle.

[0141] As expected with copper based electrocatalysts the flow cell performance depletes relative to a gradual increase in potential from 3.37 to 4.04 V within 3 h (Figure 5 and Table 1). The fluctuations observed in the potential suggest the catalyst layer degradation or instability. The average potential is average over the specified time duration. Table 1. Representative performance data on copper (Cu) based cathode GDE.Duration (min)Average Potential (V)H 2 Selec tivity (%)CO Selec tivity (%)C x H y product selectivity (%)H 2 Faradai c efficienc y (%)CO Fara daic effici ency (%)CH 4 Farad aic efficie ncy (%)C 2 H 4 Farad aic efficie ncy (%)C 2 H 6 Farad aic efficie ncy (%)203.37434115.7515.14141.4030.980.02603.40354915.8312.03170.6231.910.031003.48345015.7711.76170.6231.440.031403.76374914.5113.20170.6230.280.031804.04474013.0518.63161.4028.650.03

[0142] An appreciable selectivity for carbon monoxide (CO) and ethene (C 2 H 4 ) can be observed for the copper electrolyzer with faradaic efficiency. In addition, the faradaic efficiencies for CO and the copper-based cathode GDE start at 14 % and 30.98 %, and decrease to 16 % and 28.65 %, respectively, over the course of 180 minutes.

[0143] Figure 6 shows representative activation procedure for silver based cathode GDE in an electrolysis cell.

[0144] Figure 7 shows potential vs time run at 200 mAcm -2< for silver based cathode GDE in an electrolysis cell after activation procedure.

[0145] The electrolytic cell performs with a stable voltage at around 3 V with for the entirety of the measurement (total time = 160 min) with high selectivity for CO formation (>95 %, Table 2). The average potential is average over the specified time duration. Table 2. Representative performance data on silver (Ag) based cathode GDEDuration (min)Average Potential (V)H 2 selectivity (%)CO selectivity (%)C x H y selectivity (%)Faradaic efficiency of H 2 (%)Faradaic efficiency of CO (%)403.0529800.89345803.0219900.660451203.0219900.621441603.0119900.54344 Example 7: Performance data of AgCu alloy based cathode GDEs

[0146] It was shown that alloys of nanoparticles can lead to improved electrocatalyst performance, such as selectivity and stability, compared to their single metal counterparts. Tuning composition of alloy between 1-10 wt% Ag and 90-99 wt% Cu could influence both selectivity and stability.

[0147] AgCu alloys with the following compositions were provided: AgCu-1 10:90 silver:copper alloy (wt%) AgCu-2 1:99 silver:copper alloy (wt%)

[0148] In addition, it was experimentally confirmed that the use of ionomer / binder dispersions (5-20 wt%) including alkaline ionomers (Sustainion-X37), acidic ionomers (Nafion) and Polytetrafluoroethene (PTFE) and a mixture / combination thereof, can further influence the selectivity and stability of alloy catalyst.

[0149] Figure 8 shows representative activation procedure of AgCu-2 alloy based cathode GDE in an electrolysis cell. Figure 9 shows representative potential vs time performance at 200 mAcm -2< of the AgCu-2 alloy based cathode GDE with one ionomer only after activation procedure. Performance data is presented in Table 3. The average potential is average over the specified time duration. Table 3. Representative performance data for the AgCu-2 alloy based cathode GDEDuration (min)Average Potential (V)H 2 selectivity (%)CO selectivity (%)C 2 H 4 selectivity (%)Faradaic efficiency of H 2 (%)Faradaic efficiency of CO (%)Faradaic efficiency of C 2 H 4 (%)203.22.58.60.619.73314.2403.238.60.6311.63314.7603.213.28.70.6212.43414.4803.263.78.50.6214.43314.41003.367.470.5328.72712.31203.469.56.30.4336.924101403.5410.36.30.440249.31603.5811.260.3643.5238.4

[0150] Other selectivities: CH 4 , C 2 H 6 < 1%. Using Sustainion ionomer.

[0151] The AgCu alloy electrocatalysts produce appreciable ethene (C 2 H 4 ) in addition to H 2 and CO. Other detectable hydrocarbons include CH 4 and C 2 H 6 <1 %

[0152] Mixture of ionomers tested herein comprised aqueous Sustainion and Nafion mixtures ranging in ratios between 30:70 to 50:50 to 70:30, respectively.

[0153] Figure 10 shows representative stabilities of AgCu-1 and AgCu-2 alloy based cathode GDEs using the same mixture of Sustainion and Nafion ionomer. Both alloys were tested under the same constant current densities of 200 mAcm -2< .

[0154] Figure 11 shows representative Faradaic efficiencies of AgCu-2 alloy based cathode GDE with mixed ionomer at 200 mAcm -2< . Using the same mixture of ionomer, AgCu-2 demonstrates a more stable performance with appreciable selectivity towards C 2 H 4 with FE of up to 16 %. In addition, the production of H 2 and CO remain relatively constant.

[0155] Figure 12 shows representative comparison of Faradaic efficiencies of Cu, Ag, AgCu-1 and AgCu-2 based cathode GDEs.

[0156] Figure 13 demonstrates the influence of ionomer and ionomer mixtures on the Faradaic efficiencies of AgCu-1 and AgCu-2 alloy based cathodes GDE.

Claims

1. A cathode for an electrolysis cell, the cathode comprising a catalyst layer comprising Ag, Cu and / or AgCu alloy on a cathode support.

2. The cathode of claim 1, wherein the catalyst is a metal alloy catalyst consisting of Ag and Cu, such as wherein the catalyst layer comprises one or more of ionomers, binders and carbon powder.

3. The cathode of claim 1 or 2, wherein the catalyst layer comprises AgCu alloy nanoparticles, such as phase-separated AgCu alloy nanoparticles, for example wherein the nanoparticles have an average particle diameter in the range of 10-50 nm.

4. The cathode of any of preceding claims, wherein the catalyst layer is obtained by - providing a cathode support, such as a gas diffusion layer, for example wherein the cathode support comprises porous electrically conductive material, such as carbon fiber paper, - providing a solution comprising Ag+ and / or Cu+ and / or Cu2+ and / or a dispersion comprising Ag, Cu and / or AgCu alloy nanoparticles and optionally one or more of ionomers, binders and carbon powder, and - electrodepositing, airbrushing and / or ultrasonic spray coating the solution and / or the dispersion to the cathode support to form the catalyst layer comprising Ag, Cu and / or AgCu alloy nanoparticles on the cathode support.

5. An electrolysis cell, comprising - an anode, - the cathode of any of claims 1-4, and - an ion exchange membrane between the anode and the cathode.

6. An electrolytic device for reducing carbon dioxide to one or more products, such as to hydrocarbons, alcohols, carboxylic acids and / or to CO, the electrolytic device comprising - one or more electrolysis cells of claim 5, preferably two or more, such as wherein the electrolysis cells are flow cells arranged as one or more stack(s), and - a power supply for providing electric current and / or potential to the electrolysis cells, preferably comprising one or more electronic control means for controlling the operation of the electrolytic device, such as pressure control means arranged to control the pressure in the electrolytic device and / or in the electrolysis cells.

7. A method for preparing a cathode, the method comprising - providing a cathode support, - providing a solution comprising Ag+ and / or Cu+ and / or Cu2+, and / or providing a dispersion comprising Ag, Cu and / or AgCu alloy nanoparticles, - applying, such as electrodepositing, airbrushing and / or ultrasonic spray coating, the solution and / or the dispersion to the cathode support to form a catalyst layer comprising Ag, Cu and / or AgCu alloy nanoparticles on the cathode support to obtain the cathode of any of claims 1-4.

8. The method of claim 7, comprising - providing a cathode support, - providing a solution comprising Ag+ and / or Cu+ and / or Cu2+, and - electrodepositing the solution to the cathode support to form catalyst layer comprising Ag, Cu and / or AgCu alloy nanoparticles on the cathode support.

9. The method of claim 7, comprising - providing a dispersion comprising Ag, Cu and / or AgCu alloy nanoparticles, and - airbrushing and / or ultrasonic spray coating the dispersion to the cathode support to form a catalyst layer comprising Ag, Cu and / or AgCu alloy nanoparticles on the cathode support.

10. The cathode of any of claims 3-4, the electrolysis cell of claim 5, the electrolytic device of claim 6, or the method of claim 7 or 9, wherein the Ag, Cu and / or AgCu alloy nanoparticles are oxidated nanoparticles, preferably surface-oxidated nanoparticles.

11. The method of claim 7 or 9-10, wherein the dispersion comprising Ag, Cu and / or AgCu alloy nanoparticles comprises one or more of ionomers, binders and carbon powder.

12. A method for reducing carbon dioxide to one or more products, such as to hydrocarbons, alcohols, carboxylic acids and / or to CO, the method comprising - providing the electrolysis cell of claim 5 or 10 or the electrolytic device of claim 6 or 10, - providing a source of carbon dioxide, - supplying the carbon dioxide to the electrolysis cell and / or to the electrolytic device, - applying electric current and / or potential to the anode and the cathode to provide electrolysis to electrocatalytically reduce the carbon dioxide to generate products, and - separating one or more of the generated products, and optionally detecting one or more of the generated and / or separated product(s), and / or recovering one or more of the detected and / or separated product(s).

13. The method of claim 12, wherein the method is a method for reducing carbon dioxide to hydrocarbons comprising C1 hydrocarbons, C2 hydrocarbons or combination thereof.

14. The method of claim 12 or 13, wherein the method is a method for selectively reducing carbon dioxide to ethene.

15. Use of carbon dioxide for selectively producing one or more products, such as hydrocarbons, alcohols, carboxylic acids and / or CO, such as ethene, with the method of any of claims 12-14.

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