Partition-enhanced membraneless electrolyzer system

Abstract

A partition enhanced membraneless water electrolyzer system is described herein in which an absorbent or other bulk separation technique or separation media is used to selectively separate either oxygen over hydrogen or hydrogen over oxygen as they are produced via electrochemical reaction in the electrochemical cell of the system. A hydrogen-enriched gas product can exit the headspace of the electrochemical cell and a remaining oxygen-enriched phase can exit the headspace of a desorption chamber of the system that is fluidically coupled to the electrochemical cell. The oxygen-enriched phase can either be produced as a product or regenerated by transferring it (in a continuous or batch mode) to the desorption chamber, where an oxygen-enriched gas product is produced by changing the thermodynamic state of the separation media. A remaining / resulting oxygen lean phase can be returned to the electrolysis cell.

Description

PARTITION-ENHANCED MEMBRANELESS ELECTROLYZER SYSTEMFIELD OF THE INVENTION

[0001] The invention relates to a membraneless water electrolyzer system, where an absorbent or other bulk separation technique is used to selectively separate either oxygen over hydrogen or hydrogen over oxygen as they are produced via electrochemical reaction in the electrochemical cell, producing a hydrogen-enriched gas product exiting the electrolyzer chamber headspace and a remaining oxygen-enriched phase.BACKGROUND

[0002] Conventional electrolyzer technologies utilize membranes that separate the water electrolysis half-cell reactions and their hydrogen and oxygen gas products. The inclusion of these membranes allows for the production of high purity product streams. However, these membranes negatively impact the technoeconomics of water electrolysis in two ways. First, the membrane / catalyst assembly in PEM electrolyzers adds significant costs, for example it currently accounts for $40 / kW (Badgett, et al., “Updated Manufactured Cost Analysis for Proton Exchange Membrane Water Electrolyzers”, NREL Technical Report NREL / TP-6A20-87625, Feb 2024). Second, mass transport across the membrane induces ohmic resistance, which reduces the overall energy efficiency of the electrolyzer and increases operating costs. To reduce these contributions to capital and operating costs, some electrolyzer developers have removed the membrane from the electrochemical stack, producing so-called “membraneless” electrolyzers.

[0003] Membraneless water electrolyzer technology aims to significantly reduce hydrogen production cost, but the tradeoff is that the electrolyzer produces a mixture of hydrogen and oxygen instead of a high-purity hydrogen product. Many end-uses of hydrogen cannot tolerate large concentrations of reactive impurities, such as oxygen, requiring secondary cryogenic or pressure-swing adsorption technology to reach high hydrogen purities. These secondary processes also add cost and complexity to the electrolyzer systems to achieve gas separation.SUMMARY OF THE INVENTION

[0004] The disclosed invention comprises an alternative design and operating scheme for a membraneless electrolyzer device, which may comprise multiple chambers or zones, including an electrochemical cell, a headspace of the electrochemical cell, a desorption chamber, and a headspace of the desorption chamber. The resulting hydrogen / oxygen mixture that is produced from the operation of this device at a positive electrode and a negative electrode in the electrochemical cell is partitioned into two phases within the confines of the device, a hydrogen-enriched gas phase that exits the electrolyzer by pressure-driven flow, and an oxygen-enriched phase in the electrolysis cell. This oxygen-enriched phase may comprise a mixture of oxygen, hydrogen, a gas-carrying separation media, and other contaminant species, and hereafter is referred to as the separation media. This partitioning can be achieved via several methods, including but not limited to absorption, adsorption, and / or through the use of membranes. This partitioning comprises any change in the compositions of the partitioned phases with respect to the 2:1 molar composition of the hydrogen / oxygen mixture produced by the electrodes in the electrochemical cell. For example, the partitioned composition may comprise between 66.0-99.9 vol% hydrogen and between 0.1-33.0 vol% oxygen.

[0005] The oxygen-enriched separation media can either be produced as a product exiting the membraneless electrolyzer device by pressure-driven flow or it can be regenerated by transferring it via a continuous or batch mode to a separate chamber by pressure-driven flow, where an oxygen-enriched gas product is produced by changing the thermodynamic state of the fluid inside the chamber. These changes in thermodynamic states can be accomplished by changing the temperature (temperature-swing), oxygen partial pressure (pressure-swing), applied potential (voltage-swing), or any other method of changing the chemical potential of the initial oxygen-enriched phase. Finally, this oxygen-lean separation media is returned to the electrolysis cell by pressure-driven flow.

[0006] To that end, in some embodiments, a partition-enhanced membraneless water electrolyzer (PEMWE) system includes a membraneless electrochemical cell for producing gaseous oxygen and gaseous hydrogen from a liquid electrolyte comprising water in the membraneless electrochemical cell. The membraneless electrochemical cell includes a headspace. The PEMWE system further includes a desorption chamber having a head space. The desorption chamber is separate from the membraneless electrochemical cell and is fluidically coupled to the membraneless electrochemical cell to enable transfer of the liquidelectrolyte from and to the membraneless electrochemical cell. The oxygen and hydrogen are partitioned by selective separation within the membraneless electrochemical cell.

[0007] The summary of the invention is provided as a general introduction to some of the embodiments of the invention, and is not intended to be limiting. Additional example embodiments including variations and alternative configurations of the invention are provided herein.BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS

[0008] The accompanying drawings are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention, and together with the description serve to explain the principles of the invention.

[0009] Figure 1 shows a diagram of a first embodiment of the disclosed invention comprising an electrolyte wherein water is paired with one or more co-solvents having the properties described herein.

[0010] Figure 2 shows a diagram of a second embodiment of the disclosed invention, wherein the liquid absorbent that is added to the electrolyte is replaced by a solid adsorbent that has a selectivity for oxygen over hydrogen.

[0011] Figure 3 shows a diagram of a third embodiment of the disclosed invention, in which instead of co-locating the electrolyte with a separation media, either absorbent or adsorbent, a solid separation media is located in the headspace of the electrochemical cell.

[0012] Figure 4 shows a diagram of a fourth embodiment comprising an electrolyte wherein an absorptive additive having the properties described herein is dissolved in the water.

[0013] The desorption chamber depicted in Figures 1 , 2 and 4 can include one or more desorption methods of removing oxygen from the oxygen enriched phase such as applied vacuum, pressure reduction, temperature swing, stripping gas, applied potential, pH or a combination thereof..

[0014] Corresponding reference characters indicate corresponding parts throughout the several views of the figures. The figures represent an illustration of some of the embodiments of the disclosed invention and are not to be construed as limiting the scope ofthe invention in any manner. Some of the figures may not show all of the features and components of the invention for ease of illustration, but it is to be understood that where possible, features and components from one figure may be an included in the other figures. Further, the figures are not necessarily to scale, some features may be exaggerated to show details of particular components. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for teaching one skilled in the art to variously employ the disclosed invention.DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

[0015] As used herein, the terms "comprises," "comprising," "includes," "including," "has," "having" or any other variation thereof, are intended to cover a non-exclusive inclusion. For example, a process, method, article, or apparatus that comprises a list of elements is not necessarily limited to only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Also, use of "a" or "an" are employed to describe elements and components described herein. This is done merely for convenience and to give a general sense of the scope of the invention. This description should be read to include one or at least one and the singular also includes the plural unless specifically stated otherwise.

[0016] The phrase “selective separation” is a method of partitioning oxygen from hydrogen or hydrogen from oxygen by using one or more methods that include but are not limited to solvents having properties as defined herein, liquid absorbents capable of absorbing gaseous oxygen or liquid absorbents capable of absorbing gaseous hydrogen, solid adsorbents capable of adsorbing gaseous oxygen or solid adsorbents capable of adsorbing gaseous hydrogen, solid separation media such as membranes capable of separating oxygen or hydrogen, absorptive additives having an absorptive selectivity via chemical reaction for oxygen over hydrogen or vice versa or a combination of these methods.

[0017] The term “membraneless” as used herein is taken to mean that the cathodic chamber and anodic chamber of each electrochemical cell are not physically separated by a membrane, separator or diaphragm.

[0018] Certain exemplary embodiments of the disclosed invention are described herein and are illustrated in the accompanying figures. The embodiments described are only for purposes of illustrating the disclosed invention and should not be interpreted as limiting thescope of the invention. Other embodiments of the invention, and certain modifications, combinations and improvements of the described embodiments, evident to those skilled in the art and all such alternate embodiments, combinations, modifications, improvements are within the scope of the present invention.

[0019] Figure 1 shows a diagram of a partition-enhanced membraneless water electrolyzer (PEMWE) system 100, in accordance with some embodiments. The PEMWE system 100 includes a membraneless electrochemical cell 102 for producing gaseous oxygen (O2) and gaseous hydrogen (H2) from a liquid electrolyte 104 comprising water. The membraneless electrochemical cell 102 includes a headspace 106. PEMWE system 100 further a desorption chamber 108 having a head space 110. The desorption chamber 108 is separate from the membraneless electrochemical cell 102 and is fluidically coupled (by couplings 112a and / or 112b) to the membraneless electrochemical cell 102 to enable transfer of the liquid electrolyte 104 from and to the membraneless electrochemical cell 102. In this example, oxygen-rich separation medium is transferred from membraneless electrochemical cell 102 to desorption chamber 108 through fluid coupling 112b, and oxygen-lean separation medium is returned from the desorption chamber 108 to the membraneless electrochemical cell 102 via fluid coupling 112a. In this example, oxygen is removed from the seperation medium in the desorption chamber 108, thus converting the oxygen-rich seperation medium brought through fluid coupling 112b to the oxygen-lean separation medium returned through fluid coupling 112a. Oxygen and hydrogen are, in this manner, partitioned by selective separation within the membraneless electrochemical cell 102. The electrochemical cell 102 is membraneless in the sense that there is no physical membrane separating the anode and the cathode.

[0020] PEMWE system 100 also includes cathode 114a and anode 114b which, in use, are partially submersed in electrolyte 104 and drive the electrolysis reaction. PEMWE system 100 also include outlet 116 coupled to the headspace 106 of the membraneless electrochemical cell 102. In this example, hydrogen-enriched gas is removed from the PEMWE system 100 through the outlet 116 of the membraneless electrochemical cell 102. PEMWE system 100 also includes outlet 118 coupled to the headspace 110 of the desorption chamber 108. In this example, oxygen-enriched gas is removed from the PEMWE system 100 through the outlet 118 of the desorption chamber 108.

[0021] A first embodiment of the disclosed invention (FIG. 1) comprises an electrolyte 104 where water is paired with one or more co-solvents with the following properties:a. a co-solvent that is miscible with water and is a liquid under water electrolysis conditions;b. a co-solvent that will have minimal or no electrochemical activity under water electrolysis conditions, i.e., a co-solvent that has a wider electrochemical stability window than water. The stability window of water is approximately -0.24 to 1.0 V over Pt vs. Saturated Calomel Electrode (SCE). The stability window of acetonitrile is -3 to 2.5 V over Pt vs. SCE (Fuchigami, et al., Fundamentals and Applications of Organic Electrochemistry: Synthesis, Materials, Devices, 2015, John Wiley & Sons, First Edition); andc. a co-solvent that has a larger oxygen solubility than water and a larger oxygen / hydrogen solubility ratio than water. For example, the solubilities of oxygen and hydrogen in water near ambient conditions are approximately 0.039 and 0.0015 g / kg, respectively, yielding an oxygen / hydrogen solubility ratio of ~26 (engineeringtoolbox.com). Whereas, the solubilities of oxygen and hydrogen in acetonitrile near ambient conditions are approximately 1.886 (Franco, et al., Taianta, 1990, 37, 905-909.) and 0.016 g / kg (Brunner, et al., J. Chem. Eng. Data, 1985, 30, 269-273), respectively, yielding an oxygen / hydrogen solubility ratio of ~118. Thus, if acetonitrile were used in the disclosed invention, it would have 48 times the gas absorption capacity of water and produce a ~99% oxygen stream upon desorption.

[0022] In this first embodiment, the partitioning is achieved by selective gas absorption by the co-solvent as a liquid absorbent in the electrolysis cell 102. This absorbent can also serve as the electrolyte solution 104 for both electrochemical half-cell reactions. This liquid absorbent-electrolyte 104 serves as the separation media in this embodiment and is selected according to several criteria, including conventional water electrolysis performance metrics (such as electrochemical stability window), but also including high solubility for oxygen and a high equilibrium oxygen / hydrogen solubility selectivity. Fast oxygen absorption kinetics may also be beneficial and important to device performance.

[0023] The oxygen-enriched absorbent-electrolyte 104 is then transferred from the electrochemical cell 102 to a separate desorption chamber 108, where it is regenerated, producing an oxygen-enriched gas product into the headspace 110 of the desorption chamber 108. This oxygen-enriched gas product can be transferred out of the device for further use. This regeneration method can be described by but is not limited to the descriptions in the following desorption method options.1. Regeneration of the absorbent-electrolyte 104, which is also the desorption of the oxygen-enriched gas product, can be achieved by reducing the pressure of the desorption chamber 108 below the pressure of the electrochemical cell 102, either by pressure relief or by applying a vacuum. After desorption, the pressure of the absorbent-electrolyte 104 must be returned to the pressure of the electrochemical cell 102 via pumping before it is returned to the electrochemical cell 102.2. Alternatively, desorption can be achieved by increasing the temperature of the desorption chamber 108 above the temperature of the electrochemical cell 102, either by direct or indirect heating.3. Alternatively, desorption can be achieved by changing the applied potential of the absorbent-electrolyte 104. For example, the oxygen in the oxygen-rich separation media depicted in Figures 1 , 2 and 4 can undergo a change in oxidation state of the oxygen-absorbent adduct by changing the applied potential in the desorption chamber 108 compared to the polarity of the applied potential in the electrochemical cell 102. The change in oxidation state changes the separation media’s binding capacity for oxygen. Examples of the oxygen-absorbent adducts include nitrates, sulfates, phosphates, boric acid, chlorite, chlorate, and perchlorate.4. Alternatively, desorption can be achieved by introducing a third component, either a gas or a liquid, into the desorption chamber 108 that competitively absorbs the absorbed oxygen in the absorbentelectrolyte 104 being transferred from the electrochemical cell 102, releasing an oxygen-enriched product gas into the headspace 110 of the desorption chamber 108 or an oxygen-enriched product liquid in the desorption chamber 108. For example, the desorption chamber 108 can be purged with carbon dioxide which competitively absorbs the oxygen from the absorbent-electrolyte 104 being transferred from the electrochemical cell 102.It should be appreciated that desorption can be achieved via a combination of any or all of the above options.

[0024] As shown in FIG. 2, in a second embodiment of the PEMWE system 100, the liquid absorbent that is added to the electrolyte 104 is replaced by a solid adsorbent 200 that is dispersed in the electrolyte 103 and the solid adsorbent 200 has a selectivity for oxygen over hydrogen. Many zeolites, such as chabazite and 5A, have such differences in adsorption selectivity (Kenvin, et al., J. Colloid and Interface Sci., 2022, 178-186.). However, other sorbents may also be used, including other metal oxides, silicoaluminophosphates, metalorganic frameworks, activated carbons, polymers, and covalent-organic frameworks. This adsorbent-electrolyte mixture serves as the separation media in this second embodiment and can be circulated as a slurry from the electrochemical cell 102 to the desorption chamber 108 in a similar manner to the first embodiment and the desorption can be performed according to all the desorption method options described for the first embodiment. However, the adsorbent 200 can be confined to specific zones of either or both of the electrochemical cell 102 and the desorption chamber 108 by size-exclusion filters, gravity separation, centrifugation, or some other means of separating solids from liquids.

[0025] As shown in FIG. 3, in a third embodiment of the PEMWE system 100, instead of colocating the electrolyte 104 with a separation media, either absorbent or adsorbent, a solid separation media 300 is located in the headspace 106 of the electrochemical cell 102. This solid separation media 300 could either be a layer of adsorbents or a membrane with selective adsorption of oxygen over hydrogen. The list of potential adsorbents suitable for this embodiment is the same as the list of potential adsorbents in the second embodiment, shown in FIG. 2. If adsorbents are selected, they will be operated cyclically, by mechanically separating the headspace 106 of the electrochemical cell 102 from the liquid electrolyte 104, and desorbing the adsorbents according to the desorption mechanism options described for the first embodiment and shown in FIG. 1. If a membrane separation media is selected for this third embodiment, the membrane will be operated continuously with the operation of the electrochemical cell 102, effectively accomplishing a crude continuous gas separation in the headspace 106 of the electrolyzer. Suitable membrane materials comprise polymers, zeolites, silicoaluminophosphates, metal-organic frameworks, and covalent-organic frameworks.

[0026] As shown in FIG. 4, in a fourth embodiment of the PEMWE system 100, an absorptive additive 400 is dissolved in the electrolyte 104 that has an absorptive selectivity via chemical reaction for oxygen over hydrogen. This additive 400, and its oxygen-absorbed adduct, must be soluble in the electrolyte 104 and also have an electrochemical stability window wider than the electrolyte 104. This additive 400 may be an organic or organometallic chelating complex, redox-active species, or some other chemical compoundthat effectively increases the total oxygen loading in the electrolyte 104. For example, absorptive additives 400 that have an absorptive selectivity for oxygen over hydrogen include hydrazine, nitrites, sulfites, phosphites, borate, hypochlorite, and chlorate. In this fourth embodiment, the separation media comprises the absorptive additive 400 and the liquid electrolyte 104. Desorption is accomplished by circulating the electrolyte 104 to the desorption chamber 108 and changing the chemical potential of the oxygen-adsorbed adduct, such as by changing the pH or the applied voltage, to liberate the oxygen. After this step, the chemical potential, such as pH or applied voltage, will have to be adjusted back to the appropriate starting condition for electrolyzer operation in the electrochemical cell 102. Alternatively, the desorption method options described for the first embodiment may also be employed.

[0027] The dissolvable additive could also be added to a liquid absorbent-electrolyte 104 (described in the second embodiment). The desorption method options described for the first embodiment could be used.

[0028] The additive 400 could be removed from the electrolyte 104 or absorbent-electrolyte 104 used in the electrochemical cell 102 via solvent extraction or precipitation prior to transfer of the oxygen enriched phase to the desorption chamber 108, where the desorption methods described for the first embodiment could be used.

[0029] It should be appreciated that instead of using a selective separation that has selectivity for oxygen over hydrogen a selective separation that has selectivity for an hydrogen over oxygen scan be used. If a selective separation that has selectivity for hydrogen over oxygen selectivity is used, then the desorption chamber would be used to process a hydrogen enriched phase. The co-solvent or liquid absorbent having hydrogen over oxygen selectivity that would paired with water can be but are not limited to . The solid adsorbent having hydrogen over oxygen selectivity can be but are not limited to metal hydride forming metals, such as lithium, aluminum, copper, and zinc, as well as solids with high degrees of electron density, such as oxides, nitrides, and metal-organic frameworks. The solid separation media including membranes having hydrogen over oxygen selectivity that can be located in the headspace of the electrochemical cell can be but are not limited to metal membranes such as palladium and palladium alloys. The additive having hydrogen over oxygen selectivity that can be dissolved in the electrolyte can be but are not limited to

[0030] It is also contemplated herein that one or more examples of a process delivering oxygen over hydrogen selectivity can be deployed in conjunction with one or more examples of a process providing an hydrogen over oxygen selectivity.

[0031] In addition, performance-enhancing chemical agents can be added to the electrolyte, absorbent-electrolyte, or adsorbent-electrolyte, depending on the configuration chosen as respectively described in the above embodiments. Examples of performance enhancing chemical agents may comprise stabilization agents, solubility-enhancing agents, and pH-adjusting agents. Stabilization agents may improve device performance by preventing precipitation or deposition of solids, potentially abating common performance-degradation mechanisms such as scaling, fouling, and plugging. Solubility-enhancing agents may improve device performance by increasing the maximum loading of oxygen in the separation media or the maximum amount of separation media in the device. pH-adjusting agents may improve device performance by optimizing solubility of any of the chemicals of interest, enhancing reaction kinetics, enhancing electrochemical performance, or changing the chemical potential in the separation media to switch operation from absorption to desorption.

[0032] It will be apparent to those skilled in the art that various modifications, combinations and variations can be made in the present invention without departing from the scope of the invention. Specific embodiments, features and elements described herein may be modified, and / or combined in any suitable manner. Thus, it is intended that the disclosed invention cover the modifications, combinations and variations of this invention provided they come within the scope of the appended claims and their equivalents.

Claims

What is claimed is:

1. A partition-enhanced membraneless water electrolyzer (PEMWE) system, comprising:a membraneless electrochemical cell for producing gaseous oxygen and gaseous hydrogen from a liquid electrolyte comprising water in the membraneless electrochemical cell, wherein the membraneless electrochemical cell includes a headspace; and a desorption chamber having a head space, wherein the desorption chamber is separate from the membraneless electrochemical cell and is fluidically coupled to the membraneless electrochemical cell to enable transfer of the liquid electrolyte from and to the membraneless electrochemical cell,wherein oxygen and hydrogen are partitioned by selective separation within the membraneless electrochemical cell.

2. The partition-enhanced membraneless water electrolyzer of claim 1 , wherein the oxygen and hydrogen are partitioned by selective separation within the headspace of the membraneless electrochemical cell.

3. The partition-enhanced membraneless water electrolyzer of claim 1 , wherein the oxygen and hydrogen are partitioned using one or more methods selected from the group consisting of: absorption, adsorption and membranes.

4. The partition-enhanced membraneless water electrolyzer of claim 1 , wherein a hydrogen-enriched gas product is partitioned and exits the PEMWE system by pressure- driven flow from the headspace of the electrochemical cell or the headspace of the desorption chamber.

5. The partition-enhanced membraneless water electrolyzer of claim 1 , wherein an oxygen- enriched gas is partitioned and exits the PEMWE system by pressure-driven flow from the headspace of the electrochemical cell or the headspace of the desorption chamber.

6. The partition-enhanced membraneless water electrolyzer of claim 1 wherein an oxygen- enriched separation media is transferred to the desorption chamber by pressure-driven flow to produce an oxygen-enriched gas product and an oxygen lean phase and the oxygen lean phase is returned from the desorption chamber to the electrochemical cell.

7. The partition-enhanced membraneless water electrolyzer of claim 5, wherein the oxygen lean phase is produced by:a) increasing the temperature of the desorption chamber above the temperature of the electrochemical cell,b) reducing the pressure of the desorption chamber below the pressure of the electrochemical cell,c) changing an applied potential,d) changing an oxygen-enriched separation media’s chemical potential; or e) using any combination of a) to d).

8. The partition-enhanced membraneless water electrolyzer of claim 1 wherein a hydrogen- enriched separation media is transferred to the desorption chamber by pressure-driven flow to produce a hydrogen-enriched gas product and a hydrogen lean phase and the hydrogen lean phase is returned from the desorption chamber to the electrochemical cell.

9. The partition-enhanced membraneless water electrolyzer of claim 8, wherein the hydrogen lean phase is produced by:a) increasing the temperature of the desorption chamber above the temperature of the electrochemical cell,b) reducing the pressure of the secondary chamber below the pressure of the electrochemical cell,c) changing an applied potential,d) changing a hydrogen-enriched separation media’s chemical potential; or e) using any combination of a) to d).

10. The partition-enhanced membraneless water electrolyzer of claim 1 , wherein the selective separation is performed using a liquid absorbent that is miscible with the liquid electrolyte.

11. The partition-enhanced membraneless water electrolyzer of claim 1 , wherein the selective separation is performing using a solid adsorbent that is dispersed in the liquid electrolyte.

12. The partition-enhanced membraneless water electrolyzer of claim 1 , wherein the selective separation is performed using a chemically-reactive absorptive additive that is dissolved in the liquid electrolyte.

13. The partition-enhanced membraneless water electrolyzer of claim 1, wherein a separation media comprising one or more solid adsorbents or one or more membranes is located in the headspace of the electrochemical cell and the separation media is used to partition the hydrogen and oxygen to produce a hydrogen-enriched phase that exits the PEMWE system via pressure-driven flow and an oxygen-enriched phase that exits the PEMWE system via pressure driven flow.

14. The partition-enhanced membraneless water electrolyzer of claim 1 , wherein the selective separation comprises one or more methods that have selectivity for hydrogen over oxygen or oxygen over hydrogen.

15. The partition-enhanced membraneless water electrolyzer of claim 14, wherein the selective separation comprises only methods having selectivity for oxygen over hydrogen.

16. The partition-enhanced membraneless water electrolyzer of claim 14, wherein the selective separation comprises only methods having selectivity for hydrogen over oxygen.

17. The partition-enhanced membraneless water electrolyzer of claim 14 wherein one or more performance-enhancing chemical agents are added to the liquid electrolyte.

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