Methods for producing ammonia, and related electrochemical cells and systems

Abstract

A method of forming ammonia is disclosed. The method comprises introducing H2O to a positive electrode of an electrochemical cell. The electrochemical cell further comprises the positive electrode, a negative electrode, and an electrolyte between the positive electrode and the negative electrode. The positive electrode further comprises a catalyst formulated to accelerate a water oxidation reaction. The negative electrode comprises a catalyst formulated to accelerate a nitrogen reduction reaction. The electrolyte comprises a proton conducting material. The method also comprises introducing N2 to the negative electrode of the electrochemical cell. The method further comprises applying a potential difference between the positive electrode and the negative electrode of the electrochemical cell. Applying a potential difference comprises oxidizing the H2O to produce H+, O2, and e- at the positive electrode, transporting the H+ from the positive electrode to the electrolyte, and reducing the H+ and N2 at the negative electrode to produce a stream comprising NH3. A system and electrochemical cell are also disclosed.

Description

[0001]METHODS FOR AMMONIA, AND RELATED CELLS AND SYSTEMS PRIORITY CLAIM This application claims the benefit of the filing date of United States Provisional Patent Application Serial No.63 / 584,096, filed September 20, 2023, for “METHODS AND SYSTEMS FOR PRODUCING AMMONIA, AND RELATED ELECTROCHEMICAL CELLS,” the disclosure of which is hereby incorporated herein in its entirety by this reference. STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT This invention was made with government support under Contract Number DE- AC07-05-ID14517 awarded by the United States Department of Energy. The government has certain rights in the invention. TECHNICAL FIELD The disclosure, in various embodiments, relates to methods and systems for producing ammonia through water oxidation and nitrogen reduction reactions, and to associated electrochemical cells. BACKGROUND Ammonia (NH3) is a valued compound finding use in a wide variety of commercial and industrial applications. For example, NH3is used as a precursor to various food, fertilizer, pharmaceutical, and cleaning products. However, conventional methods of producing NH3(e.g., the Haber-Bosch process) through nitrogen gas (N2) hydrogenation are energy- and carbon-intensive and can undesirably result in the production of significant amounts of greenhouse gases (e.g., CO2) from combustion-based processes employed to generate the required energy. The Haber-Bosch process includes two major stages, (1) H2 production from natural gas in a steam methane reforming reactor and (2) N2separation from air and conventional NH3 production in a Haber-Bosch reactor. When natural gas is used as a feedstock, the Haber-Bosch process generates about 2.3 tons of fossil-derived CO2 per ton of NH3 produced. The Haber-Bosch process is conducted at a high pressure within a range of from about 25 MPa to about 35 MPa and a temperature within a range of from about 450°C to about 550°C to achieve a high yield of NH3. These operating conditions, low energy efficiency, on natural gas, and substantial CO2 emissions are serious constraints for the viability of the Haber-Bosch process in a net-zero carbon and sustainable economy. Electrochemical techniques for NH3production have also been investigated but use a large overpotential and low temperatures to achieve high reaction rates. However, the NH3selectivity is low with these electrochemical techniques. SUMMARY Embodiments of the disclosure include a method of forming ammonia (NH3). The method comprises introducing H2O to a positive electrode of an electrochemical cell. The electrochemical cell further comprises the positive electrode, a negative electrode, and an electrolyte between the positive electrode and the negative electrode. The positive electrode comprises a catalyst formulated to accelerate an oxidation reaction. The negative electrode comprises a catalyst formulated to accelerate a nitrogen reduction reaction. The electrolyte comprises a proton conducting material. The method also comprises introducing N2 to the negative electrode of the electrochemical cell. The method further comprises applying a potential difference between the positive electrode and the negative electrode of the electrochemical cell. Applying a potential difference comprises oxidizing the H2O to produce H+, O2, and e- at the positive electrode, transporting the H+from the positive electrode to the electrolyte, and reducing the H+and N2 at the negative electrode to produce a stream comprising NH3. Embodiments of the disclosure also include an electrochemical cell. The electrochemical cell comprises a positive electrode formulated to facilitate an oxidation reaction to produce H+, O2, and e- from H2O. The positive electrode comprises a first perovskite material and a support material. The support material comprises a second perovskite material exhibiting an ionic conductivity greater than or equal to about 10-2S / cm at one or more temperatures within a range of from about 350°C to about 700°C. The electrochemical cell further comprises a negative electrode formulated to facilitate a reduction reaction to produce NH3from N2and the H+. The electrochemical cell further comprises an electrolyte between the positive electrode and the negative electrode. The electrochemical cell further comprises a power source configured to apply a potential difference between the positive electrode and the negative electrode. Embodiments of the disclosure further include a system for producing ammonia. The system comprises a source of steam and a source of N2. The system further comprises an electrochemical apparatus in fluid communication with the source of steam and the source of N2. The electrochemical apparatus comprises a housing structure configured and positioned to receive a steam stream from the source of steam and to receive a N2 stream from the source of N2. The electrochemical apparatus further comprises an electrochemical cell within an internal chamber of the housing structure. The electrochemical cell comprises a positive electrode formulated to facilitate an oxidation reaction to produce H+, O2, and e- from H2O; a negative electrode formulated to facilitate a reduction reaction to produce NH3from N2and the produced H+; and a proton-conducting membrane between the positive electrode and the negative electrode. The proton conducting membrane comprises an electrolyte material having an ionic conductivity greater than or equal to about 10-2S / cm at one or more temperatures within a range of from about 350°C to about 700°C. The system further comprises a power source configured to apply a potential difference between the positive electrode and the negative electrode. BRIEF DESCRIPTION OF THE DRAWINGS FIG.1 is a simplified schematic view of a system for producing NH3, in accordance with embodiments of the disclosure; FIG.2 is a simplified schematic view of a system for producing NH3, in accordance with additional embodiments of the disclosure; FIG.3 is a simplified view of a system for producing NH3, in accordance with additional embodiments of the disclosure; and FIG.4 is a simplified flowchart of a method of producing NH3, in accordance with additional embodiments of the disclosure. MODE(S) FOR CARRYING OUT THE INVENTION Methods and systems for producing NH3 through water oxidation and nitrogen reduction reactions are disclosed. In some embodiments, a method of producing NH3comprises delivering steam (e.g., gaseous H2O) and N2 to an electrochemical apparatus including at least one electrochemical cell therein. The electrochemical cell includes a positive electrode (e.g., anode), a negative electrode (e.g., cathode), and an electrolyte (e.g., a proton-conducting membrane) between the positive electrode and the negative electrode. The positive electrode is formulated to facilitate production of hydrogen ions (H+), oxygen (O2), and electrons (e-) from steam. The negative electrode is formulated to facilitate production of NH3 from N2 and the produced H+and e-. The electrolyte may exhibit an ionic conductivity greater than or equal to 10-2S / cm at one or more temperatures within a range of from about 350°C to about 700°C. The steam is introduced to the positive electrode of the electrochemical cell, the N2 is introduced to the negative electrode of the electrochemical cell, and a potential difference is applied between the positive electrode and the negative electrode of the electrochemical cell to produce the NH3. The methods, systems, and apparatus of the disclosure may be more efficient (e.g., increasing NH3 production efficiency; reducing equipment, material, and / or energy requirements), less complicated, and result in a significant reduction in carbon intensity as compared to conventional methods, conventional systems, and conventional apparatuses for producing NH3. The NH3produced by the methods and systems may be at least substantially free of carbon materials since the inputs (e.g., reactants) and outputs (e.g., products) are at least substantially carbon-free. The methods and systems may enable the NH3to be sustainably produced from N2 and H2O using clean (e.g., carbon-free) processes, such as renewable, solar, nuclear, or carbon capture processes. The following description provides specific details, such as material compositions and processing conditions (e.g., temperatures, pressures, flow rates, etc.) in order to provide a thorough description of embodiments of the disclosure. However, a person of ordinary skill in the art will understand that the embodiments of the disclosure may be practiced without necessarily employing these specific details. Indeed, the embodiments of the disclosure may be practiced in conjunction with conventional systems and methods employed in the industry. In addition, only those process components and acts necessary to understand the embodiments of the present disclosure are described in detail below. A person of ordinary skill in the art will understand that some process components (e.g., pipelines, line filters, valves, temperature detectors, flow detectors, pressure detectors, and the like) are inherently disclosed herein and that adding various conventional process components and acts would be in accord with the disclosure. In addition, the drawings accompanying the application are for illustrative purposes only and are not meant to be actual views of any particular material, device, or system. As used herein, the terms “catalyst material” and “catalyst” each mean and include a material formulated to promote one or more reactions, resulting in the formation of a product. As used herein, the term “negative electrode” means and includes an electrode having a relatively lower electrode potential in an electrochemical cell (i.e., lower than the electrode potential in a positive electrode therein). Conversely, as used herein, the term “positive electrode” means and includes having a relatively higher electrode potential in an electrochemical cell (i.e., higher than the electrode potential in a negative electrode therein). As used herein the term “electrolyte” means and includes an ionic conductor, which can be in a solid state, a liquid state, or a gas state (e.g., plasma). As used herein, the term “compatible” means that a material does not undesirably react, decompose, or absorb another material, and also that the material does not undesirably impair the chemical and / or mechanical properties of the another material. As used herein, spatially relative terms, such as “beneath,” “below,” “lower,” “bottom,” “above,” “upper,” “top,” “front,” “rear,” “left,” “right,” and the like, may be used for ease of description to describe one element’s or feature’s relationship to another element(s) or feature(s) as illustrated in the figures. Unless otherwise specified, the spatially relative terms are intended to encompass different orientations of the materials in addition to the orientation depicted in the figures. For example, if materials in the figures are inverted, elements described as “below” or “beneath” or “under” or “on bottom of” other elements or features would then be oriented “above” or “on top of” the other elements or features. Thus, the term “below” can encompass both an orientation of above and below, depending on the context in which the term is used, which will be evident to one of ordinary skill in the art. The materials may be otherwise oriented (e.g., rotated 90 degrees, inverted, flipped) and the spatially relative descriptors used herein interpreted accordingly. As used herein, the singular forms “a,” “an,” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. As used herein, “and / or” includes any and all combinations of one or more of the associated listed items. As used herein, the term “configured” refers to a size, shape, material composition, material distribution, and arrangement of one or more of at least one structure and at least one apparatus facilitating operation of one or more of the structure and the apparatus in a pre-determined way. As used herein, the term “substantially” in reference to a given parameter, property, or condition means and includes to a degree that one of ordinary skill in the art would understand that the given parameter, property, or condition is met with a degree of variance, such as within acceptable manufacturing tolerances. By way of example, depending on the particular parameter, property, or condition that is substantially met, the parameter, property, or condition may be 90.0% met, at least 95.0% met, at least 99.0% met, at least 99.9% met, or even 100.0% met. As used herein, “about” or “approximately” in reference to a numerical value for a particular parameter is inclusive of the numerical value and a degree of variance from the numerical value that one of ordinary skill in the art would understand is within acceptable tolerances for the particular parameter. For example, “about” or “approximately” in reference to a numerical value may include additional numerical values within a range of from 90.0 percent to 110.0 percent of the numerical value, such as within a range of from 95.0 percent to 105.0 percent of the numerical value, within a range of from 97.5 percent to 102.5 percent of the numerical value, within a range of from 99.0 percent to 101.0 percent of the numerical value, within a range of from 99.5 percent to 100.5 percent of the numerical value, or within a range of from 99.9 percent to 100.1 percent of the numerical value. FIG.1 illustrates a simplified schematic view of a system 100 (e.g., an electrochemical system) for producing ammonia (NH3) according to embodiments of the disclosure. The system 100 may be used to convert nitrogen (N2) and steam (e.g., gaseous H2O) into NH3. In some embodiments, the system 100 is used to convert the N2and H2O into NH3 without using or generating carbon materials (e.g., hydrocarbons, CO2). As shown in FIG.1, the system 100 may include at least one steam source 102 (e.g., a containment vessel, a steam generator), at least one N2 source 104 (e.g., containment vessel), and at least one electrochemical apparatus 106 in fluid communication with each of the steam source 102 and the N2 source 104. The electrochemical apparatus 106 includes a housing structure 108 and at least one electrochemical cell 110 contained within the housing structure 108. The electrochemical cell 110 is electrically connected (e.g., coupled) to a power source 118, and includes a positive electrode 112 (e.g., an anode), a negative electrode 116 (e.g., a cathode), and an electrolyte 114 (e.g., a proton-conducting electrolyte, a proton-conducting membrane) between the positive electrode 112 and the negative electrode 116. The positive electrode 112 and the negative electrode 116 may include highly active and selective catalysts towards a water oxidation reaction (WOR) and a N2 reduction reaction (NRR). The WOR and NRR are conducted substantially simultaneously to produce the NH3. The power source 118 may provide clean (e.g., carbon-free) electricity (e.g., electricity that is generated without direct emissions of greenhouse gases, such as CO2, during the generating process). The system 100 may be configured as a protonic ceramic electrochemical membrane reactor (PC-EMR). In some embodiments, the electrochemical cell protonic ceramic electrochemical cell. The electrochemical cell 110 may operate as an electrolysis cell to convert nitrogen (N2) into ammonia (NH3). The electrochemical cell 110 may operate in reverse as a fuel cell to generate electricity from NH3(e.g., consuming at least a portion of the NH3produced when the electrochemical cell 110 is operated as an electrolysis cell). In a fuel cell mode, NH3 acts as a source of H+ions and / or H2gas to produce electricity (e.g., the Oxygen Reduction Reaction (ORR)) in a reversal of reactions (1) and (2) below. In the fuel cell mode, the NH3and O2product streams are used as feed streams and the N2and H2O feed streams are product streams as discussed in more detail below. As shown in FIG.1, optionally, the system 100 may also include at least one heating apparatus 120 operatively associated with the electrochemical apparatus 106. The heating apparatus 120 may generate heat via a clean (e.g., carbon-free) process (e.g., a process that generates heat without direct emissions of greenhouse gases, such as CO2, during the process). The system 100 may include a vacuum pump (not shown) in operative communication with the housing structure 108. During use and operation, the system 100 directs a steam stream 122 from the steam source 102 into the electrochemical apparatus 106 to interact with the positive electrode 112 of the electrochemical cell 110. The steam stream 122 functions as a source of hydrogen. A potential difference (e.g., a voltage) is applied between the positive electrode 112 and the negative electrode 116 of the electrochemical cell 110 by the power source 118 so that as the steam interacts with the positive electrode 112, H atoms of the H2O release their electrons (e-) to generate oxygen (O2), hydrogen ions (H+) (e.g., protons), and electrons (e-) via a water oxidation reaction (WOR), according to the following equation: 2H2O ^ 4H++ O2 + 4e- (1). The protons produced by the oxidation or electrolysis of water use a carbon-free process. The generated H+permeate (e.g., diffuse) across the electrolyte 114 to the negative electrode 116. A flux of H+across the electrolyte 114 may be controlled by the potential difference applied between the positive electrode 112 and the negative electrode 116. The applied potential may be from about open circuit voltage to about 3V. The generated e- are directed to the power source 118 through external circuitry (not shown). The e- generated at the positive electrode 112 may, for example, flow from the positive electrode 112 through the power source 118 and into electrode 116. At the negative electrode 116, the generated H+exiting the electrolyte 114 react with N2delivered into the electrochemical apparatus 106 from an N2 stream 124 from the N2 source 104 and e- received from the power source 118 in the presence of a catalyst material of the negative electrode 116 to produce NH3 via a nitrogen reduction reaction (NRR), according to the following equation: N2+ 6H++ 6e- ^ 2NH3(2). The WOR and NRR may so the electrochemical apparatus 106 by the negative electrode 116 at the same time as the O2, H+, and e- are produced. By incorporating the WOR and NRR into a single electrochemical apparatus 106, the NH3 may be efficiently produced. The NH3 may also be produced with reduced carbon emissions by using carbon-free processes. Unlike conventional methods (e.g., the Haber- Bosch process) of forming NH3 that react N2 with hydrogen gas (H2(g)), the system 100 directly reacts H+with the N2to form NH3. Accordingly, the formation of NH3at the negative electrode 116 is not constrained (e.g., limited) by the previous formation of H2 through a hydrogen evolution reaction (HER). Since the NH3produced according to embodiments of the disclosure use protons, rather than H2 as in the Haber-Bosch process, relatively low pressures may be used. However, a pressure slightly above ambient pressure may be used to increase the production rate of the NH3. In addition, the NRR may occur at reduced pressures (e.g., ambient pressure) relative to conventional catalytic hydrogenation methods. In addition, molecules of N2 may directly diffuse to active sites without being constrained by low solubility and slow transport in liquids as occurs in the Haber-Bosch process. Furthermore, the system 100 may produce NH3without using or generating carbon materials (e.g., hydrocarbons, CO2), which lowers the carbon emissions associated with NH3formation and reduces the cost of forming NH3. Thus, the system 100 and disclosed method according to embodiments of the disclosure may achieve a higher efficiency (e.g., a higher Faradaic efficiency) for producing NH3 as compared to conventional systems and methods. The produced NH3 exits the electrochemical apparatus 106 as an NH3 stream 126. At the positive electrode 112, the generated O2 and, if present, unreacted H2O, may exit the electrochemical apparatus as O2 stream 128. One or more of the NH3 stream 126 and the O2 stream 128 may be substantially free of carbon materials. In some embodiments, the NH3stream 126 and the O2stream 128 are at least substantially free of carbon materials, such as having less than or equal to about 1% by volume of carbon materials. As described in further detail below, the production of H+, O2, and e- at the positive electrode 112 and NH3at the negative electrode 116 may at least partially depend on the material compositions and flow rates of the steam stream 122 and the N2 stream 124; the configuration (e.g., size, shape, material composition, material distribution, arrangement) of the positive electrode 112, including the types, quantities, distribution, and properties (e.g., geometric properties, thermodynamic properties, etc.) of catalyst materials thereof promoting water oxidation reactions; the configuration of the electrolyte 114, and the impact thereof on the diffusivity (e.g., diffusion rate) of generated H+therethrough; the configuration of the negative electrode 116, including the types, quantities, and properties (e.g., geometric properties, thermodynamic properties, etc.) of catalyst materials thereof; and the operational parameters (e.g., temperatures, pressures, etc.) of the electrochemical apparatus 106. Such operational factors may be controlled (e.g., adjusted, maintained, etc.) as desired to control the quantities and rate of production of the H+, O2, and e- produced at the positive electrode 112 and to control the quantity and rate of production of the NH3 produced at the negative electrode 116. The steam source 102 may include at least one apparatus configured and operated to produce the steam stream 122, which includes water in the form of steam. When the electrochemical cell 110 is operated as a fuel cell, the steam source 102 may receive an H2O recycle stream (not shown) containing one or more phases of H2O exiting the electrochemical apparatus 106. By way of non-limiting example, the steam source 102 may comprise a boiler apparatus configured and operated to heat liquid H2O to a temperature greater than or equal to about 100°C. In some embodiments, the steam source 102 is configured and operated to convert the liquid H2O to steam having a temperature within a range of an operating temperature of the electrochemical cell 110 of the electrochemical apparatus 106, such as a temperature within a range of from about 350°C to about 700°C, such as from about 350°C to about 650°C, from about 400°C to about 700°C, from about 400°C to about 650°C, or from about 400°C to about 600°C. In some embodiments, the steam source 102 is configured and operated to convert the liquid H2O into steam having a temperature below the operating temperature of the electrochemical cell 110. In such embodiments, the heating apparatus 120 may be employed to further heat the steam to the operational temperature of the electrochemical cell 110, as described in further detail below. The steam stream 122 may be formed of and include gaseous H2O. The steam stream 122 may, optionally, include one or more other materials (e.g., molecules), such as one or more of nitrogen (N2), argon (Ar), carbon dioxide (CO2), and oxygen (O2). In some embodiments, the steam stream 122 is at least substantially free of materials other than H2O. In some embodiments, the steam stream 122 is at least substantially free of carbon materials. The steam stream 122 may be substantially gaseous (e.g., may only include a single gaseous phase) or may include a combination of gaseous and liquid phases. In some embodiments, the steam stream 122 is at least substantially gaseous. One or more apparatuses (e.g., heat exchangers, pumps, compressors, expanders, mass flow control devices, etc.) may be employed within the system 100 to adjust the one or more of the temperature, pressure, and flow rate of the steam stream 122 delivered into the electrochemical apparatus 106. A single (e.g., only one) steam stream 122 may be directed into the electrochemical apparatus 106 from the steam source 102, or multiple (e.g., more than one) steam streams 122 may be directed into the electrochemical apparatus 106 from the steam source 102. If multiple steam streams 122 are directed into the electrochemical apparatus 106, each of the multiple steam streams 122 may exhibit at least substantially the same properties (e.g., at least substantially the same material composition, at least substantially the same temperature, at least substantially the same pressure, at least substantially the same flow rate, etc.), or at least one of the multiple steam streams 122 may exhibit one or more different properties (e.g., a different material composition, a different temperature, a different pressure, a different flow rate, etc.) than at least one other of the multiple steam streams 122. The N2 stream 124 entering the electrochemical apparatus 106 may be formed of and include N2. The N2may be present in the N2stream 124 in one or more of a gaseous phase and a liquid phase. The phase(s) of the N2 (and, hence, a temperature and a pressure of the N2stream 124) may at least partially depend on the operating temperature of the electrochemical cell 110 of the electrochemical apparatus 106. The N2 stream 124 may only include N2 (e.g., about 100% N2), or may include N2 and one or more other materials. In some embodiments, the N2 stream 124 is substantially free of materials other than N2. In some embodiments, the N2 stream 124 is substantially free of carbon materials. One or more apparatuses (e.g., heat exchangers, pumps, compressors, expanders, mass flow control devices, etc.) may be employed the system 100 to adjust one or more of the temperature, pressure, and flow rate of the N2stream 124 delivered into the electrochemical apparatus 106. A single (e.g., only one) N2stream 124 may be directed into the electrochemical apparatus 106, or multiple (e.g., more than one) N2 streams 124 may be directed into the electrochemical apparatus 106. If multiple N2streams 124 are directed into the electrochemical apparatus 106, each of the multiple N2 streams 124 may exhibit at least substantially the same properties (e.g., at least substantially the same material composition, at least substantially the same temperature, at least substantially the same pressure, at least substantially the same flow rate, etc.), or at least one of the multiple N2streams 124 may exhibit one or more different properties (e.g., a different material composition, a different temperature, a different pressure, a different flow rate, etc.) than at least one other of the multiple N2 streams 124. In various embodiments, the N2 stream 124 may be a so-called “wet” stream (e.g., including up to about 50% H2O by volume). The presence of water in the N2stream may facilitate formation of hydroxyl ions (OH-) on the negative electrode 116 (e.g., on the catalyst and / or support material), which in turn may improve the selectivity and efficiency of the cathode in reducing N2 to NH3. The heating apparatus 120, if present, may comprise at least one apparatus (e.g., one or more of a combustion heater, an electrical resistance heater, an inductive heater, and an electromagnetic heater) configured and operated to heat one or more of the steam stream 122, the N2 stream 124, and at least a portion of the electrochemical apparatus 106 to an operating temperature of the electrochemical apparatus 106. The operating temperature of the electrochemical apparatus 106 may at least partially depend on a material composition of the electrolyte 114 of the electrochemical cell 110, as described in further detail below. In some embodiments, the heating apparatus 120 heats one or more of the steam stream 122, the N2stream 124, and at least a portion of the electrochemical apparatus 106 to a temperature within a range of from about 350°C to about 700°C, such as from about 350°C to about 650°C, from about 400°C to about 700°C, from about 400°C to about 650°C, or from about 400°C to about 600°C. In additional embodiments, such as in embodiments where a temperature of one or more of the steam stream 122 and the N2 stream 124 is already within the operating temperature range of the electrochemical cell 110 of the electrochemical apparatus 106, the heating apparatus 120 may be omitted (e.g., absent) from the system 100. With continued reference to electrochemical apparatus 106, including the housing structure 108 and the electrochemical cell 110 thereof, is configured and operated to form the NH3 stream 126 and the O2 stream 128 from the steam stream 122 and the N2stream 124 according to the reactions of Equations (1) and (2) above. The housing structure 108 may exhibit any shape (e.g., a tubular shape, a quadrilateral shape, a spherical shape, a semi-spherical shape, a cylindrical shape, a semi-cylindrical shape, truncated versions thereof, or an irregular shape) and size able to contain (e.g., hold) the electrochemical cell 110 therein, to receive and direct the steam stream 122 to the positive electrode 112 of the electrochemical cell 110, to direct O2 formed at the positive electrode 112 away from the electrochemical apparatus 106 as the O2stream 128, and to direct the NH3 formed at the negative electrode 116 of the electrochemical cell 110 away from the electrochemical apparatus 106 as the NH3stream 126. In addition, the housing structure 108 may be formed of and include any material (e.g., glass, metal, alloy, polymer, ceramic, composite, combination thereof, etc.) compatible with the operating conditions (e.g., temperatures, pressures, etc.) of the electrochemical apparatus 106. The housing structure 108 may at least partially define at least one internal chamber 130 at least partially surrounding the electrochemical cell 110. The electrochemical cell 110 may serve as a boundary between a first region 132 (e.g., an anodic region) of the internal chamber 130 configured and positioned to receive the steam stream 122 and to direct the O2 stream 128 from the electrochemical apparatus 106, and a second region 134 (e.g., a cathodic region) of the internal chamber 130 configured and positioned to receive the NH3 produced at the negative electrode 116 of the electrochemical cell 110. Molecules (e.g., H2O) of the steam stream 122 may be substantially limited to the first region 132 of the internal chamber 130 by the configurations and positions of the housing structure 108 and the electrochemical cell 110. Keeping the second region 134 of the internal chamber 130 substantially free of molecules from the steam stream 122 circumvents additional processing of the produced NH3(e.g., to separate the produced NH3from H2O and / or O2) that may otherwise be necessary if the components of the steam stream 122 were also delivered to within the second region 134 of the internal chamber 130. As shown in FIG.1, the positive electrode 112 and the negative electrode 116 of the electrochemical cell 110 are electrically coupled to the power source 118, and the electrolyte 114 is disposed on and between the positive electrode 112 and the negative electrode 116. The electrolyte 114 is configured and formulated to conduct H+from the positive electrode 112 to the negative 116, while electrically insulating the negative electrode 116 from the positive electrode 112. Electrons generated at the positive electrode 112 through the reaction of Equation (1) described above may, for example, flow from the positive electrode 112 into a negative current collector (not shown), through the power source 118 and a positive electrode current collector (not shown), and into negative electrode 116 to facilitate the protonation of N2at the negative electrode 116 to form NH3through the reaction of Equation (2) described above. The electrochemical cell 110 may operate at an operational temperature within a range of from about 350°C to about 700°C, such as from about 350°C to about 650°C, from about 400°C to about 700°C, from about 400°C to about 650°C, or from about 400°C to about 600°C. The electrochemical cell 110 may operate at current densities greater than or equal to about 0.1 amperes per square centimeter (A / cm2), such as greater than or equal to about 0.5 A / cm2, greater than or equal to about 1.0 A / cm2, or greater than or equal to about 2.0 A / cm2. In some embodiments, the electrochemical cell may operate at current densities within a range of from about 0.1 A / cm2to about 3.0 A / cm2, such as within a range of from about 1.0 A / cm2to about 2.0 A / cm2. By adjusting the operational temperature and the current density, the NH3production rate of the electrochemical cell 110 may be tailored. The electrolyte 114 may be a thin, highly conductive proton-conducting membrane, such as a protonic ceramic membrane. The electrolyte 114 may be formed of and include at least one electrolyte material exhibiting an ionic conductivity (e.g., H+conductivity) greater than or equal to about 10-2S / cm, such as within a range of from about 10-2S / cm to about 1 S / cm, at one or more temperatures within a range of from about 350°C to about 700°C, such as from about 400°C to about 600°C. The electrolyte material may be formulated to remain substantially adhered (e.g., laminated) to the positive electrode 112 and the negative electrode 116 at relatively high current densities, such as at current densities greater than or equal to about 0.1 A / cm2(e.g., greater than or equal to about 0.5 A / cm2, greater than or equal to about 1.0 A / cm2, greater than or equal to about 2.0 A / cm2). In some embodiments, the electrolyte 114 is formed of and includes at least one perovskite material having an operational temperature (e.g., a temperature at which the conductivity of the perovskite material is greater than or equal to about 10-2S / cm, such as within a range of from about 10-2S / cm to about 1 S / cm) within a range of from about 350°C to about 650°C. The electrolyte 114 may be formed of and include a perovskite material exhibiting a cubic lattice structure with a general formula ABO3-δ, where A may comprise barium (Ba), B one or more of zirconium (Zr), cerium (Ce), yttrium (Y), and ytterbium (Yb), and ^ is the oxygen deficit and may be 0 ≤ ^ ≤ 0.5. By way of non-limiting example, the electrolyte 114 may be formed of and include one or more of a yttrium- and ytterbium-doped barium-zirconate-cerate (BZCYYb), such as BaZr0.8-yCeyY0.2-xYbxO3-δ, where x and y are dopant levels (e.g., 0 ≤ x ≤ 0.2, 0 ≤ y ≤ 0.8) and δ is the oxygen deficit (e.g., 0 ≤ ^ ≤ 0.5) (e.g., BaZr0.1Ce0.7Y0.1Yb0.1O3-δ(BZCYYb1711), BaZr0.4Ce0.4Y0.1Yb0.1O3-δ(BZCYYb4411), BaZr0.3Ce0.5Y0.1Yb0.1O3-δ(BZCYYb3511)), doped barium-zirconate (BaZrO3) (e.g., yttrium-doped BaZrO3 (BZY), such as BaZr0.8Y0.2O3-δ where δ is the oxygen deficit (e.g., 0 ≤ ^ ≤ 0.5)), barium-yttrium- stannate (Ba2(YSn)O5.5), and barium-calcium-niobate (Ba3(CaNb2)O9). In some embodiments, the electrolyte 114 is formed of and includes BZCYYb. The electrolyte 114 may be at least substantially homogeneous (e.g., exhibiting an at least substantially uniform material composition throughout the electrolyte 114) or may be at least substantially heterogeneous (e.g., exhibiting varying material composition throughout the electrolyte 114). In some embodiments, the electrolyte 114 is at least substantially homogeneous. In additional embodiments, the electrolyte 114 is at least substantially heterogeneous. The electrolyte 114 may, for example, include a stack of at least two (e.g., at least three, at least four, etc.) different electrolyte materials. The electrolyte 114 may exhibit any desired dimensions (e.g., length, width, thickness) and any desired shape, such as one of a cubic shape, a cuboidal shape, a tubular shape, a tubular spiral shape, a spherical shape, a semi-spherical shape, a cylindrical shape, a semi-cylindrical shape, a conical shape, a triangular prismatic shape, a truncated version of one or more of the foregoing, or an irregular shape. The dimensions and shape of the electrolyte 114 may be selected such that the electrolyte 114 at least substantially intervenes between opposing surfaces of the positive electrode 112 and the negative electrode 116. A thickness of the electrolyte 114 may at least partially depend on the material composition and thickness of the positive electrode 112. In some embodiments, a thickness of the electrolyte 114 is at least about 100 microns (µm), such as, for example, at least about 150 µm, at least about 200 µm, or at least about 250 µm. The positive electrode 112 may be formed of and include a material compatible with the material of the electrolyte 114 and a material of the negative electrode 116 under the operating conditions (e.g., temperature, pressure, current density, etc.) of the electrochemical cell 110. The material composition of the positive electrode 112 may facilitate production of H+, O2, and e- The material of the positive electrode 112 may be a porous material. The positive electrode 112 may be formed of and include at least one perovskite material (referred to herein as a “positive electrode perovskite material”) that accelerates (e.g., catalyzes) reaction rates (e.g., water oxidation reaction rates) at the positive electrode 112 to produce H+, O2, and e- from steam in accordance with Equation (1) above. The positive electrode perovskite material may comprise a catalyst material. By way of non-limiting example, the positive electrode perovskite material of the positive electrode 112 may be formed of and include one or more of a triple conducting perovskite material, such as Pr(Co1-x-y-z, Nix, Mny, Fez)O3- ^, wherein 0 ≤ x ≤ 0.9, 0 ≤ y ≤ 0.9, 0 ≤ z ≤ 0.9, and ^ is an oxygen deficit (e.g., 0 ≤ ^ ≤ 0.5) (e.g., PrNi0.5Co0.5O3-^(PNC55)) or (Pr1-xLnx)(Ba7,Sr1-y)(Coz,Tn1-z)O5+^, wherein Ln is selected from La, Nd, Ce, Pm, Sm, Er, Gd, Dy, Ho, and Yb; Tn is selected from Fe, Ni, Cu, Zn, Mn, Cr, and Nd, 0 ≤ x ≤ 1, 0 ≤ y ≤ 1, 0 ≤ z ≤ 1, and ^ is the oxygen deficit (e.g., 0 ≤ ^ ≤ 0.5) (e.g., Pr0.5La0.5BaCo2 O5+^(PLBC)); a double perovskite material, such as MBa1- xSrxCo2-yFeyO5+δ, wherein x and y are dopant levels (e.g., 0 ≤ x ≤ 0.9, 0 ≤ y ≤ 0.9), ^ is the oxygen deficit (e.g., 0 ≤ ^ ≤ 0.5), and M is Pr, Nd, or Sm (e.g., PrBa0.5Sr0.5Co1.5Fe0.5O5+ ^(PBSCF), NdBa0.5Sr0.5Co1.5Fe0.5O5+ ^, SmBa0.5Sr0.5Co1.5Fe0.5O5+ ^) or MBa1-xCaxCo2O5+δ, wherein x is a dopant level (e.g., 0 ≤ x ≤ 0.5), ^ is the oxygen deficit (e.g., 0 ≤ ^ ≤ 0.5) and M is Pr, Nd, or Sm (e.g., PrBa0.8Ca0.2Co2O5+^(PBCC)); a single perovskite material, such as Sm1-xSrxCoO3-δ (SSC), BaZr1-x-y-zCoxFeyYzO3-δ, or SrScxNdyCo1-x-yO3-δ, wherein x, y, and z are dopant levels (e.g., 0 ≤ x ≤ 0.5, 0 ≤ y ≤ 0.5, 0 ≤ z ≤ 0.2)and ^ is the oxygen deficit (e.g., 0 ≤ ^ ≤ 0.5); a Ruddleson-Popper-type perovskite material, such as M2NiO4-δ, wherein ^ is the oxygen deficit (e.g., 0 ≤ ^ ≤ 0.5) and M is La, Pr, Gd, or Sm (e.g., La2NiO4-δ, Pr2NiO4-δ, Gd2NiO4-δ, Sm2NiO4-δ); and a single perovskite / perovskite composite material such as SSC-BZCYYb. In some embodiments, the positive electrode 112 is formed of and includes PNC55. In some embodiments, the entire positive electrode 112 is formed of and includes the positive electrode perovskite material. In some embodiments, the positive electrode 112 is formed of and includes a support material and the positive electrode perovskite material. The support material may be a porous material. The porous material of the support material may exhibit a total pore volume to a total support material volume ratio within a range of from about 1:20 to about 1:2. The porous material may include pores exhibiting an average pore size, measured by scanning electron microscopy (SEM) within a range of from about 10 nm to about 10 µm, such as, for example, of from about 10 nm to about 100 nm, from about 10 nm to about 500 nm, from about 10 nm to about 1 µm, from about 500 nm to about 2 µm, from about 1 µm to about 5 µm, from about 2 µm to about 8 µm, from about 3 µm to about 7 µm, or from about 5 µm to about 10 µm. The positive electrode perovskite material may at least partially fill the pores of the porous support material. In some embodiments, the positive electrode perovskite material at least substantially fills the pores of the porous support material. The at least one positive electrode perovskite material may be at least substantially homogeneously distributed on, over, and / or throughout the support material or may be at least substantially heterogeneously distributed on, over, and / or throughout the support material. By way of non-limiting example, the positive electrode 112 may exhibit a concentration gradient of the at least one positive electrode perovskite material on, over, and / or throughout the support material. The positive electrode 112 may be formed by impregnating or infiltrating the at least one positive electrode perovskite material into the support material. The support material may be formulated to accelerate reaction rates (e.g., water oxidation reaction rates) at the positive electrode 112 to produce H+, O2, and e- from steam in accordance with Equation (1) above. By way of non-limiting example, the support material of the positive electrode 112 may be formed of and include at least one perovskite material exhibiting an ionic conductivity (e.g., H+conductivity) greater than or equal to about 10-2S / cm, such as within a range of from about 10-2S / cm to about 1 S / cm, at one or more temperatures within a range of from about 350°C to about 700°C, such as from about 400°C to about 600°C. The support material of the positive electrode 112 may comprise a perovskite material exhibiting a cubic lattice structure with a general formula ABO3-δ, where A may comprise barium (Ba), B may comprise one or more of zirconium (Zr), cerium (Ce), yttrium (Y), and ytterbium (Yb), and ^ is the oxygen deficit (e.g., 0 ≤ ^ ≤ 0.5). By way of non-limiting example, the porous perovskite structure may be formed of and include one or more of a yttrium- and ytterbium-doped barium-zirconate-cerate (BZCYYb), such as BaZr0.8-yCeyY0.2-xYbxO3-δ, where x and y are dopant levels (e.g., 0 ≤ x ≤ 0.2, 0.1 ≤ y ≤ 0.7) and δ is the oxygen deficit (e.g., 0 ≤ ^ ≤ 0.5) (e.g., BaZr0.1Ce0.7Y0.1Yb0.1O3-δ (BZCYYb1711), BaZr0.4Ce0.4Y0.1Yb0.1O3-δ (BZCYYb4411), BaZr0.3Ce0.5Y0.1Yb0.1O3-δ(BZCYYb3511)), doped barium-zirconate (BaZrO3) (e.g., yttrium-doped BaZrO3 (BZY), such as BaZr0.8Y0.2O3-δ where δ is the oxygen deficit (e.g., 0 ≤ ^ ≤ 0.5)), barium-yttrium- (YSn)O5.5), and barium-calcium-niobate (Ba3(CaNb2)O9). In some embodiments, the support material of the positive electrode 112 is formed of and includes the same material as the electrolyte 114. In some embodiments, the support material of the positive electrode 112 is formed of and includes BZCYYb. In some embodiments, the positive electrode 112 includes the support material formed of and including BZCYYb and the positive electrode perovskite material formed of and including PNC55. The positive electrode perovskite material and / or the support material of the positive electrode 112 may be doped with a catalyst material. In some embodiments, the support material of the positive electrode 112 is doped with the catalyst material. In additional embodiments, the positive electrode 112 does not include the support material and the positive electrode perovskite material is doped with the catalyst material. The catalyst material may comprise a single (e.g., only one) element (e.g., a single metal), or may comprise multiple (e.g., more than one) elements (e.g., multiple metals). The catalyst material of the positive electrode 112 may comprise one or more of elemental particles, alloy particles, and composite particles. The catalyst material may be formulated to accelerate (e.g., catalyze) reaction rates (e.g., water oxidation reaction rates) at the positive electrode 112 to produce H+, O2, and e- from steam in accordance with Equation (1) above. The catalyst material may be formed of and include at least one metal, such as, for example, one or more of palladium (Pd), platinum (Pt), rhodium (Rh), ruthenium (Ru), iridium (Ir), nickel (Ni), cobalt (Co), and combinations thereof. In some embodiments, the catalyst material is Ni. In some embodiments, the positive electrode 112 includes the support material formed of and including BZCYYb doped with Ni (Ni-BZCYYb) and the positive electrode perovskite material formed of and including PNC55. The negative electrode 116 may be formed of and include a material compatible with the material of the electrolyte 114 and the material of the positive electrode 112 under the operating conditions (e.g., temperature, pressure, current density) of the electrochemical cell 110. The material composition of the negative electrode 116 may facilitate production of NH3from N2from the N2stream 124 and the H+and e- produced from the steam of the steam stream 122. The material of the negative electrode 116 may be a porous material. The negative electrode 116 may be formed of and include at least one perovskite material. The negative electrode 116 may include at least one catalyst material thereon, thereover, and / or therein that accelerates reaction rates (e.g., nitrogen reduction reaction rates) at the negative electrode produce NH3 from N2, H+, and e- in accordance with Equation (2) above. The catalyst material of the negative electrode 116 may, for example, comprise a metallic material (e.g., a metal, an alloy, a composite of two or more metals and / or alloys) formulated to accelerate reaction rates at the negative electrode 116 to produce NH3 from N2, H+, and e-. The catalyst material of the negative electrode 116 may comprise a single (e.g., only one) element (e.g., a single metal), or may comprise multiple (e.g., more than one) elements (e.g., multiple metals). The catalyst material of the negative electrode 116 may comprise one or more of elemental particles, alloy particles, and composite particles. In some embodiments, the catalyst material of the negative electrode 116 comprises elemental particles of one or more metals formulated to accelerate reaction rates at the negative electrode 116 to produce NH3from N2, H+, and e-. In additional embodiments, the catalyst material of the negative electrode 116 comprises alloy particles individually including an alloy comprising two or more metals, wherein at least one of the metals is formulated to accelerate reaction rates at the negative electrode 116 to produce NH3from N2, H+, and e-. In further embodiments, the catalyst material of the negative electrode 116 comprises composite particles including a first metal and a second metal partially (e.g., less than completely) coating (e.g., covering, encapsulating) the first metal, (e.g., composite particles individually including a shell of the second metal partially coating a core of the first metal), wherein at least one of the metals is formulated to accelerate reaction rates at the negative electrode 116 to produce NH3from N2, H+, and e-. In yet further embodiments, the catalyst material of the negative electrode 116 comprises composite particles including an alloy metal partially coating the another alloy, wherein at least one of the alloys includes a metal formulated to accelerate reaction rates at the negative electrode 116 to produce NH3 from N2, H+, and e-. In still further embodiments, the catalyst material of the negative electrode 116 comprises composite particles including an elemental metal partially coating an alloy, wherein at least one of the elemental metal and the alloy is formulated to accelerate reaction rates at the negative electrode 116 to produce NH3 from N2, H+, and e-. In yet still further embodiments, the catalyst material of the negative electrode 116 comprises composite particles including an alloy partially coating an elemental, wherein at least one of the alloy and the elemental metal is formulated to accelerate reaction rates at the negative electrode 116 to produce NH3 from N2, H+, and e-. As a non-limiting example, if the proton-conducting membrane 114 comprises a perovskite material (e.g., a BZCYYb, a BSNYYb, a doped BaCeO3, a doped BaZrO3, Ba2(YSn)O5.5, Ba3(CaNb2)O9, etc.) temperature within a range of from about 350°C to about 700°C, the negative electrode 116 may comprise a catalyst- doped perovskite material compatible with the perovskite material of the proton-conducting membrane 114. The negative electrode 116 may, for example, comprise a cermet material comprising at least one catalyst material including one or more (e.g., each) of ruthenium (Ru) and an Ru alloy, and at least one perovskite; such as one or more of an Ru / perovskite cermet (Ru-perovskite) material (e.g., Ru-BZCYYb, Ru-BSNYYb, Ru- PrBa0.5Sr0.5Co1.5Fe0.5O5-δ(Ru-PBSCF) where δ is the oxygen deficiut (e.g., 0 ≤ δ ≤ 0.5), Ru- PrNi0.5Co0.5O3- ^(Ru-PNC) where δ is the oygen deficit (e.g., 0 ≤ δ ≤ 0.5), Ru- Pr0.5Ba0.5CoxFe1-xO3, Ru-Pr0.5Ba0.5FeO3(e.g., 0 ≤ x ≤ 0.5), Ru-BaCeO3, Ru-BaZrO3, Ru- Ba2(YSn)O5.5, Ru-Ba3(CaNb2)O9), an RuNi / perovskite cermet (RuNi-perovskite) material (e.g., RuNi-BZCYYb, RuNi-BSNYYb, RuNi-PBSCF, RuNi-PNC, RuNi- Pr0.5Ba0.5CoxFe1-xO3 (e.g., 0 ≤ x ≤ 0.5), RuNi-Pr0.5Ba0.5FeO3, RuNi-BaCeO3, RuNi-BaZrO3, RuNi- Ba2(YSn)O5.5, RuNi-Ba3(CaNb2)O9), an RuCe / perovskite cermet (RuCe-perovskite) material (e.g., RuCe-BZCYYb, RuCe-BSNYYb, RuCe-PBSCF, RuCe-PNC, RuCe- Pr0.5Ba0.5CoxFe1-xO3(e.g., 0 ≤ x ≤ 0.5), RuCe-Pr0.5Ba0.5FeO3, RuCe-BaCeO3, RuCe-BaZrO3, RuCe-Ba2(YSn)O5.5, RuCe-Ba3(CaNb2)O9), an RuNiCe / perovskite cermet (RuNiCe- perovskite) material (e.g., RuNiCe-BZCYYb, RuNiCe-BSNYYb, RuNiCe-PBSCF, RuNiCe-PNC, RuNiCe- Pr0.5Ba0.5CoxFe1-xO3 (e.g., 0 ≤ x ≤ 0.5), RuNiCe-Pr0.5Ba0.5FeO3, RuNiCe-BaCeO3, RuNiCe-BaZrO3, RuNiCe-Ba2(YSn)O5.5, RuNiCe-Ba3(CaNb2)O9), and an Ru / La0.25Ce0.75O1.875 (LDC) / perovskite cermet (Ru-metal oxide-perovskite) material (e.g., Ru / LDC-BZCYYb, Ru / LDC-BSNYYb, Ru / LDC-PBSCF, Ru / LDC-PNC, Ru / LDC- Pr0.5Ba0.5CoxFe1-xO3 (e.g., 0 ≤ x ≤ 0.5), Ru / LDC-Pr0.5Ba0.5FeO3, Ru / LDC-BaCeO3, Ru / LDC-BaZrO3, Ru / LDC-Ba2(YSn)O5.5, Ru / LDC-Ba3(CaNb2)O9). The catalyst material may include one or more of elemental particles individually including Ru (e.g., Ru particles), alloy particles individually including Ru (e.g., RuCe particles, RuNi particles, RuNiCe particles), composite particles (e.g., core / shell particles) individually including Ru (e.g., composite particles of Ru and Ni, composite particles of Ru and Ce, composite particles of Ru, Ni, and Ce), and a composite material including Ru and a metal oxide (e.g., Ru / LDC). In some embodiments, the negative electrode 116 comprises Ru / LDC- BZCYYb. A Ru / LDC catalyst material is disclosed in U.S. Application Serial No.17 / 445,687 entitled “METHODS OF FORMING METAL NANOMATERIALS,” the disclosure of which application is incorporated by reference herein in its entirety. Particles (e.g., elemental particles, composite particles) of the catalyst material of the catalyst-doped material of the negative electrode 116 may be nano- sized (e.g., individually having a cross-sectional width or diameter less than about one (1) µm, such as less than or equal to about 100 nm, less than or equal to about 20 nm, or less than or equal to about 10 nm). In addition, the catalyst-doped material of the negative electrode 116 may exhibit any amount (e.g., concentration) and distribution of the catalyst material and any ratio of components thereof facilitating desired nitrogen reduction reaction rates at the negative electrode 116. The positive electrode 112 and the negative electrode 116 may each individually exhibit any desired dimensions (e.g., length, width, thickness) and any desired shape (e.g., a cubic shape, cuboidal shape, a tubular shape, a tubular spiral shape, a spherical shape, a semi-spherical shape, a cylindrical shape, a semi-cylindrical shape, a conical shape, a triangular prismatic shape, a truncated version of one or more of the foregoing, and irregular shape). The dimensions and the shapes of the positive electrode 112 and the negative electrode 116 may be selected relative to the dimensions and the shape of the proton-conducting membrane 114 such that the proton-conducting membrane 114 substantially intervenes between opposing surfaces of the positive electrode 112 and the negative electrode 116. Thicknesses of the positive electrode 112 and the negative electrode 116 may each individually be within a range of from about 10 µm to about 1000 µm. By selecting the proton-conducting membrane 114 to exhibit a high conductivity, and by selecting catalysts in the positive electrode 112 and the negative electrode 116 to exhibit high selectivity and activity to the WOR and NRR, the system 100 may be used to more efficiently and cheaply produce the NH3. By coupling thermocatalysis and electrocatalysis, reaction kinetics for producing the NH3may also be increased. Using intermediate operating temperatures (from about 400°C to about 600°C) provides a balance between the reaction kinetics and the thermodynamics of the WOR and the NRR. Since heat and electricity used in the system 100 may be obtained from carbon-free processes, such as from renewable, solar, nuclear, or carbon capture processes, the NH3may be formed with significant reductions in process energy and carbon intensity compared to conventional processes. Energy consumption may be reduced by at least about 20% and carbon emissions may be reduced by at least 50% compared to the conventional Haber- Bosch process. Since the NH3 stream 126 and the O2 stream 128 are produced in different regions 132, 134 of the internal chamber 130 and do not need to be subsequently separated, the purity of the produced NH3 and O2 greater than that produced by conventional processes. The electrochemical cell 110, including the positive electrode 112, the proton- conducting membrane 114, and the negative electrode 116 thereof, may be formed through conventional processes (e.g., rolling process, milling processes, shaping processes, pressing processes, consolidation processes, etc.), which are not described in detail herein. The electrochemical cell 110 may be mono-faced or bi-faced and may have a prismatic, folded, wound, cylindrical, or jelly rolled configuration. The electrochemical cell 110 may be placed within the housing structure 108 to form the electrochemical apparatus 106 and may be electrically connected to the power source 118. Although the electrochemical apparatus 106 is depicted as including a single (i.e., only one) electrochemical cell 110 in FIG.1, the electrochemical apparatus 106 may include any number of electrochemical cells 110. Put another way, the electrochemical apparatus 106 may include a single (e.g., only one) electrochemical cell 110, or may include multiple (e.g., more than one) electrochemical cells 110. If the electrochemical apparatus 106 includes multiple electrochemical cells 110, each of the electrochemical cells 110 may be substantially the same (e.g., exhibit substantially the same components, component sizes, component shapes, component material compositions, component material distributions, component positions, component orientations, etc.) and may be operated under substantially the same conditions (e.g., substantially the same temperatures, pressures, flow rates, etc.), or at least one of the electrochemical cells 110 may be different (e.g., exhibit one or more of different components, different component sizes, different component shapes, different component material compositions, different component material distributions, different component positions, different component orientations, etc.) than at least one other of the electrochemical cells 110 and / or may be operated under different conditions (e.g., different temperatures, different pressures, different flow rates, etc.) than at least one other of the electrochemical cells 110. By way of non-limiting example, one of the electrochemical cells 110 may be configured for and operated under a different temperature (e.g., different operating temperature resulting from a different material composition of one of more components thereof, such as a different material composition of the electrolyte 114 thereof) than at least one other of the electrochemical cells 110. In some embodiments, two or more electrochemical cells 110 are provided in parallel with one another within the housing structure 108 of the electrochemical apparatus 106 and may individually portion of the N2 protonation products (e.g., NH3) directed out of the electrochemical apparatus 106 as the NH3stream 126. In addition, although the system 100 is depicted as including a single (i.e., only one) electrochemical apparatus 106 in FIG.1, the system 100 may include any number of electrochemical apparatuses 106. Put another way, the system 100 may include a single (e.g., only one) electrochemical apparatus 106, or may include multiple (e.g., more than one) electrochemical apparatuses 106. If the system 100 includes multiple electrochemical apparatuses 106, each of the electrochemical apparatuses 106 may be substantially the same (e.g., exhibit substantially the same components, component sizes, component shapes, component material compositions, component material distributions, component positions, component orientations, etc.) and may be operated under substantially the same conditions (e.g., substantially the same temperatures, pressures, flow rates, etc.), or at least one of the electrochemical apparatus 106 may be different (e.g., exhibit one or more of different components, different component sizes, different component shapes, different component material compositions, different component material distributions, different component positions, different component orientations, etc.) than at least one other of the electrochemical apparatuses 106 and / or may be operated under different conditions (e.g., different temperatures, different pressures, different flow rates, etc.) than at least one other of the electrochemical apparatuses 106. By way of non-limiting example, one of the electrochemical apparatuses 106 may be configured for and operated under a different temperature (e.g., a different operating temperature resulting from a different material composition of one of more components of an electrochemical cell 110 thereof, such as a different material composition of the proton-conducting membrane 114 thereof) than at least one other of the electrochemical apparatuses 106. In some embodiments, two or more electrochemical apparatuses 106 are provided in parallel with one another. Each of the two or more electrochemical apparatuses 106 may individually receive a steam stream 122 and a N2stream 124 and individually form an NH3stream 126 and a O2stream 128. In additional embodiments, two or more electrochemical apparatuses 106 are provided in series with one another. Still referring to FIG.1, the O2 stream 128 and the NH3 stream 126 exiting the electrochemical apparatus 106 may individually be utilized or disposed of as desired. In some embodiments, the O2 stream 128 and the NH3 stream 126 are individually delivered into one or more storage vessels (not shown) for subsequent use, as desired. In additional embodiments, at least a portion of one or more of the O2 stream 128 and the NH3 stream 126 may be utilized (e.g., heat one or more components (e.g., the heating apparatus 120 (if present); the electrochemical apparatus 106; etc.) and / or streams (e.g., the steam stream 122, the N2 stream 124) of the system 100. By way of non-limiting example, if the heating apparatus 120 (if present) is a combustion-based apparatus, at least a portion of one or more of the O2 stream 128 and the NH3 stream 126 may be directed into the heating apparatus 120 and undergo a combustion reaction to efficiently heat one or more of the steam stream 122 entering the electrochemical apparatus 106, the N2 stream 124 entering the electrochemical apparatus 106, and at least a portion of the electrochemical apparatus 106. Utilizing the O2 stream 128 and / or the NH3 stream 126 as described above may reduce the electrical power requirements of the system 100 by enabling the utilization of direct thermal energy. The NH3 stream 126 may be recovered and used as a precursor in the food, fertilizer, pharmaceutical, and cleaning product industries. In addition to the NH3 stream 126, the O2 stream 128 may be a useful co- product of the system and methods according to embodiments of the disclosure. The NH3 production rate may be greater than or comparable to conventional electrochemical routes and exhibit improved Faradaic efficiency. Thermal energy input into (e.g., through the heating apparatus 120 (if present)) and / or generated by the electrochemical apparatus 106 may also be used to heat one or more other components and / or streams of the system 100. By way of non-limiting example, the O2 stream 128 and / or the NH3 stream 126 exiting the electrochemical apparatus 106 may be directed into a heat exchanger configured and operated to facilitate heat exchange between the O2 stream 128 and / or the NH3 stream 126 of the system 100 and one or more other relatively cooler streams (e.g., the steam stream 122, the N2stream 124) of the system 100 to transfer heat from the O2 stream 128 and / or the NH3 stream 126 to the relatively cooler stream(s) to facilitate the recovery of the thermal energy input into and generated within the electrochemical apparatus 106. The recovered thermal energy may increase process efficiency and / or reduce operational costs without having to react (e.g., combust) O2 of the O2 stream 128 and / or NH3 of the NH3 stream 126. FIG.2 illustrates a simplified schematic view of a system 200 for producing NH3from steam and N2. The system 200 may be similar to the system 100 previously described with reference to FIG.1. The system 200 may include additional process components (e.g., valves, back pressure regulators, controllers, pressure indicators, pressure regulators, thermocouples, condensers, generators, separators, etc.), which are not all shown in FIG.2. In various embodiments, system an electrochemical apparatus 206, which may be similar to the electrochemical apparatus 106 previously described with reference to FIG.1, within a reactor vessel 208, such as a pressurized reactor vessel, including a heat source 220 (e.g., a furnace) that maintains the system 200 at a selected temperature. The interior of reactor vessel 208 includes an electrochemical cell 210 that may be similar to the electrochemical cell 110 previously described with reference to FIG.1. The electrochemical cell 210 includes a positive electrode 212, a negative electrode 216, and an electrolyte 214 separating the positive and negative electrode. The positive electrode 212 may be similar to the positive electrode 112 previously described with reference to FIG.1. The negative electrode 216 may also be similar to the negative electrode 116 previously described with reference to FIG.1. The electrolyte 214 also may be similar to the electrolyte 114 previously described with reference to FIG.1. In various embodiments, the internal chamber 230 containing electrochemical cell 210 is divided into two chambers: a first chamber 232 (positive electrode chamber) and a second chamber 234 (negative electrode chamber). In various embodiments, system 200 also includes at least one inlet to the positive electrode chamber and at least one outlet from the positive electrode chamber. H2O is introduced into steam generator 202 and then into the first chamber 232 and exposed to the positive electrode 212. The steam may be mixed with captured ambient air (not shown) before being introduced into the first chamber 232. The steam stream 222 interacts with the positive electrode 212 to undergo a WOR, which produces H+, e-, and O2from the H2O. The produced O2 and other gases (e.g., unreacted H2O) in the first chamber 232 are removed via one or more outlets as oxygen stream 226. The oxygen stream 226 may be introduced into a condenser 238 to liquify excess H2O. H2O 250 is separated from O2248 and any other gases (e.g., N2) in the condenser 238 into vessels 246 and 244, respectively. The H2O 250 and / or O2248 may be stored, used, or released. For example, the H2O in container 246 may be recycled back to the steam generator 202 and the O2may be recovered in container 244. The O2 may be a valuable co-product that is used to generate additional revenue. In various embodiments, the electrolyte 214 is a proton-conducting electrolyte and an electrical insulator. An electric potential is applied by a power source 218 (e.g., a DC power supply) across the electrochemical cell 210 to help drive the H+produced at the positive electrode 212 to the negative electrode 216. The electric potential may be part of an electrically conductive path positive and negative electrodes and facilitating transport of the e- between the positive and negative electrodes. In various embodiments, system 200 also includes at least one inlet to the second chamber 234 and at least one outlet from the second chamber 234. N2, which may be isolated from air, is introduced into the second chamber 234 from nitrogen source 204. In various embodiments, the N2stream 224 is substantially pure. At negative electrode 216, the N2 reacts with the H+and the e- in a NRR to form NH3. System 200 further includes at least one outlet from the second chamber 234 from which the NH3and unreacted N2exit. The NH3 stream 228 is transported to a separator 236 where the NH3252 is separated from the N2254 and the N2is moved to container 240 and may be recycled 256 back to the second chamber 234. The NH3252 may be substantially pure and is recovered as purified NH3product stream into vessel 242. The steam generator 202, reactor vessel 208, power source 218, heat source 220, and separator 236 of the system 200 may be commercially available components. FIG.3 illustrates a simplified view of a system 300 for producing NH3. The system 300 may be similar to systems 100 and 200 previously described with reference to FIGS.1 and 2. The system 300 may produce NH3using electricity and heat produced from carbon-free (e.g., so-called “green”) processes, such as from renewable, solar, nuclear, or carbon capture processes, and steam produced from a carbon-free process. Thus, the NH3produced by the system 300 may be formed with significant reductions in process energy and carbon intensity compared to conventional processes. The system 300 also may include a carbon-free process for generating heat and / or electricity used to separate N2 from air. The system 300 may also use a carbon-free electrical source to provide the DC power to apply a potential between the anode and cathode in the stack. The system 300 may include a stack of electrochemical cells 310 configured as PC- EMR units, as shown in FIG.3, to increase the production rate of NH3. The stack has an increased active area compared to a single electrochemical cell 310, increasing the production rate of NH3. One or more of the electrochemical cells 310 may be similar to the electrochemical cells 110 and 210 previously described with reference to FIGS.1 and 2. By way of example only, dimensions of the electrochemical cells 310 may be about 10 cm by about 10 cm. However, smaller or larger dimensions may be used depending on a desired production rate of NH3. The electrochemical cells 310 include a positive electrode 312, a negative electrode 316, and an electrolyte 314 separating the positive and negative electrodes. The positive electrode 312 may be similar to the positive electrodes 112 and 212 previously reference to FIGS.1 and 2. The negative electrode 316 may also be similar to the negative electrodes 116 and 216 previously described with reference to FIGS.1 and 2. The electrolyte 314 also may be similar to the positive electrodes 114 and 214 previously described with reference to FIGS.1 and 2. The enlarged region of FIG.3 illustrates the positive electrode 312, negative electrode 316, and electrolyte 314. However, it is understood that the stack of the system 300 includes additional electrochemical cells 310, positioned above and below the illustrated electrochemical cells 310 in the enlarged region, with the electrochemical cells 310 being a repeating unit in the stack. By way of example only, the stack may include two or more electrochemical cells 310, such as greater than or equal to about 5 electrochemical cells 310, greater than or equal to about 10 electrochemical cells 310, greater than or equal to about 20 electrochemical cells 310, or greater than or equal to about 50 electrochemical cells 310. The system 300 may also be configured as a modular system that contains multiple stacks. By way of example only, the system 300 may include 50 electrochemical cells 310 in a single stack and a total of 100 stacks. By way of example only, the NH3 may be produced at about 0.47 kg / day, about 47 kg / day, or about 470 kg / day depending on the configuration of the electrochemical cells 310 and the operating conditions, such as the operating temperature, the operating pressure, and the current density used. The pressure may also be slightly increased above ambient pressure to increase the production rate of the NH3. The positive electrode 312 is exposed to steam stream 322, where the H2O is converted into H+, e-, and O2. The H+are transported across the electrolyte 314 to the negative electrode 316. The e- are transported through external circuitry (not shown) to the negative electrode 316. The negative electrode 316 is exposed to nitrogen stream 324, where the N2 is disassociated and reacted with the H+and e- to form NH3. The O2 is removed from the positive electrode 312 side of the electrochemical cell 310 as an O2stream 326 and is recovered from the system 300. The NH3 is removed from the negative electrode 316 side of the electrochemical cell 310 as NH3steam 328 and is recovered from the system 300. FIG.4 provides a simplified flowchart for a method 400 of producing NH3 from H2O(g) and N2 using a PC-EMR. The method may be performed using a system similar to systems 100, 200, or 300 previously described with references to FIGS.1 to 3. Method 400 may include generating H2O(g) 402 (e.g., with a boiler or evaporator) and supplying the H2O(g) 408 to the anode PC-EMR. The method 400 may also include providing a source of N2404 (e.g., N2purified from air) and supplying the N2406 to the cathode side of the PC-EMR. The PC-EMR may include catalysts on the anode and cathode sides that are formulated to accelerate WOR and NRR reactions, respectively. H+produced at the cathode are diffused 410 across an electrolyte to the anode. The e- also produced at the cathode are conducted (e.g., routed) 412 through external circuitry to the anode. The N2 reacts with the H+and e- to produce NH3. The cathode product stream, including NH3and N2, is removed 414 from the PC-EMR and separated 416 into NH3product stream 418 and the N2 is recycled 426 back to the N2 source. The anode product stream, including O2and H2O(g), is removed 420 from the PC-EMR and the H2O is separated 422 and recycled 428 back to the steam generator. The O2 and any other gases form another product stream 424. Additional non-limiting example embodiments of the disclosure are set forth below: Embodiment No.1: A method of forming ammonia (NH3), comprising: introducing H2O to a positive electrode of an electrochemical cell, the electrochemical cell comprising: the positive electrode, comprising a catalyst formulated to accelerate an oxidation reaction; a negative electrode comprising a catalyst formulated to accelerate a nitrogen reduction reaction; and an electrolyte between the positive electrode and the negative electrode, the electrolyte comprising a proton conducting material; introducing N2to the negative electrode of the electrochemical cell; and applying a potential difference between the positive electrode and the negative electrode of the electrochemical cell, the applying a potential difference comprising: oxidizing the H2O to produce H+, O2, and e- at the positive electrode; transporting the H+from the positive electrode to the electrolyte; and reducing the H+and N2 at the negative electrode to produce a stream comprising NH3. Embodiment No.2: The method of embodiment 1, further comprising selecting the electrolyte to comprise an electrolyte material exhibiting an ionic conductivity greater than or equal to about 10-2S / cm at one or more temperatures within a range of from about 350°C to about 700°C. Embodiment No.3: The method of embodiments 1-2, further comprising selecting the positive electrode to comprise a support material and the positive electrode catalyst, the positive electrode catalyst comprising a first perovskite material formulated to accelerate the oxidation reaction to produce the H+, the O2, and the e-, and the support material comprising a second perovskite material exhibiting an ionic conductivity greater than or equal to about 10-2S / cm at one or more within a range of from about 350°C to about 700°C. Embodiment No.4: The method of embodiments 1-3, wherein introducing H2O to a positive electrode of an electrochemical cell comprises introducing steam to the positive electrode. Embodiment No.5: The method of embodiments 1-4, wherein reducing the H+and N2 at the negative electrode to produce a stream comprising NH3 comprises producing a the stream comprising NH3that is at least substantially free of carbon. Embodiment No.6: The method of embodiments 1-5, wherein applying a potential difference between the positive electrode and the negative electrode comprises maintaining the electrochemical cell at a temperature of from about 400°C to about 600°C. Embodiment No.7: The method of embodiments 1-6, wherein oxidizing the H2O to produce H+, O2, and e- at the positive electrode and reducing the H+and N2 at the negative electrode to produce a stream comprising NH3 comprises concurrently producing the NH3 and the O2. Embodiment No.8: The method of embodiment 1-7, wherein oxidizing the H2O to produce H+, O2, and e- at the positive electrode comprises producing a O2stream that is substantially free of carbon at the positive electrode. Embodiment No.9: The method of embodiment 1-8, further comprising directing the e- generated at the positive electrode to a power source. Embodiment No.10: The method of embodiment 1-9, further comprising introducing H2O to the negative electrode of the electrochemical cell. Embodiment No.11: The method of embodiment 10, wherein introducing N2and H2O to the negative electrode of the electrochemical cell comprises introducing a mixture of N2and H2O comprising about 3% H2O. Embodiment No.12: An electrochemical cell, comprising: a positive electrode formulated to facilitate an oxidation reaction to produce H+, O2, and e- from H2O, the positive electrode comprising a first perovskite material and a support material, the support material comprising a second perovskite material exhibiting an ionic conductivity greater than or equal to about 10-2S / cm at one or more temperatures within a range of from about 350°C to about 700°C; a negative electrode formulated to facilitate a reduction reaction to produce NH3 from N2 and the H+; an electrolyte between the positive electrode and the negative electrode; and a power source configured to apply a potential difference between the positive electrode and the negative electrode. Embodiment No.13: The cell of embodiment 12, wherein the negative electrode comprises a catalyst material formulated to accelerate the reduction reaction to produce the NH3 from the N2 and the H+, the catalyst material comprising one or more of Ru and an Ru alloy. Embodiment No.14: The electrochemical cell of embodiments 12-13, wherein the electrolyte comprises a proton-conducting membrane. Embodiment No.15: The electrochemical cell of embodiment 14, wherein the proton-conducting membrane comprises a perovskite material exhibiting a cubic lattice structure with a general formula ABO3-δ, wherein: A comprises barium (Ba); B comprises one or more of zirconium (Zr), cerium (Ce), yttrium (Y), and ytterbium (Yb); and ^ is an oxygen deficit. Embodiment No.16: A system for producing ammonia, comprising: a source of steam; a source of N2; an electrochemical apparatus in fluid communication with the source of steam and the source of N2, and comprising: a housing structure configured and positioned to receive a steam stream from the source of steam and to receive a N2 stream from the source of N2; an electrochemical cell within an internal chamber of the housing structure, and comprising: a positive electrode formulated to facilitate an oxidation reaction to produce H+, O2, and e- from H2O; a negative electrode formulated to facilitate a reduction reaction to produce NH3 from N2 and the produced H+; and a proton-conducting membrane between the positive electrode and the negative electrode and comprising an electrolyte material having an ionic conductivity greater than or equal to about 10-2S / cm at one or more temperatures within a range of from about 350°C to about 700°C; and a power source configured to apply a potential difference between the positive electrode and the negative electrode. Embodiment No.17: The system of embodiment 16, further comprising: an outlet from the housing structure configured to receive a stream of O2 produced at the positive electrode; and an outlet from the housing structure configured to receive NH3produced at the negative electrode. Embodiment No.18: The system of embodiments 16-17, wherein the internal chamber of the housing structure comprises a first chamber adjacent to the positive electrode and a second chamber adjacent to the negative electrode. Embodiment No.19: The system 16-18, wherein the positive electrode comprises a first perovskite material and a support material, the support material comprising a second perovskite material. Embodiment No.20: The system of embodiment 19, wherein the second perovskite material comprises a material exhibiting an ionic conductivity greater than or equal to about 10-2S / cm at one or more temperatures within a range of from about 350°C to about 700°C. While the disclosure is susceptible to various modifications and alternative forms, specific embodiments have been shown by way of example in the drawings and have been described in detail herein. However, the disclosure is not limited to the particular forms disclosed. Rather, the disclosure is to cover all modifications, equivalents, and alternatives falling within the scope of the following appended claims and their legal equivalent. For example, elements and features disclosed in relation to one embodiment may be combined with elements and features disclosed in relation to other embodiments of the disclosure.

Claims

What is claimed is:

1. A method of forming ammonia (NH3), comprising: introducing H2O to a positive electrode of an electrochemical cell, the electrochemical cell comprising: the positive electrode, comprising a catalyst formulated to accelerate an oxidation reaction; a negative electrode. comprising a catalyst formulated to accelerate a nitrogen reduction reaction; and an electrolyte between the positive electrode and the negative electrode, the electrolyte comprising a proton conducting material; introducing N2 to the negative electrode of the electrochemical cell; and applying a potential difference between the positive electrode and the negative electrode of the electrochemical cell, the applying a potential difference comprising: oxidizing the H2O to produce H+, O2, and e- at the positive electrode; transporting the H+from the positive electrode to the electrolyte; and reducing the H+and N2at the negative electrode to produce a stream comprising NH3.

2. The method of claim 1, further comprising selecting the electrolyte to comprise an electrolyte material exhibiting an ionic conductivity greater than or equal to about 10-2S / cm at one or more temperatures within a range of from about 350°C to about 700°C.

3. The method of claim 1, further comprising selecting the positive electrode to comprise a support material and the positive electrode catalyst, the positive electrode catalyst comprising a first perovskite material formulated to accelerate the oxidation reaction to produce the H+, the O2, and the e-, and the support material comprising a second perovskite material exhibiting an ionic conductivity greater than or equal to about 10-2S / cm at one or more temperatures within a range of from about 350°C to about 700°C.

4. The method of claim 1, introducing H2O to a positive electrode of an electrochemical cell comprises introducing steam to the positive electrode.

5. The method of claim 1, wherein reducing the H+and N2at the negative electrode to produce a stream comprising NH3 comprises producing a the stream comprising NH3that is at least substantially free of carbon.

6. The method of claim 1, wherein applying a potential difference between the positive electrode and the negative electrode comprises maintaining the electrochemical cell at a temperature of from about 400°C to about 600°C.

7. The method of claim 1, wherein oxidizing the H2O to produce H+, O2, and e- at the positive electrode and reducing the H+and N2 at the negative electrode to produce a stream comprising NH3 comprises concurrently producing the NH3 and the O2.

8. The method of claim 1, wherein oxidizing the H2O to produce H+, O2, and e- at the positive electrode comprises producing an O2stream that is substantially free of carbon at the positive electrode.

9. The method of claim 1, further comprising directing the e- generated at the positive electrode to a power source.

10. The method of claim 1, further comprising introducing H2O to the negative electrode of the electrochemical cell.

11. The method of claim 10, wherein introducing N2 and H2O to the negative electrode of the electrochemical cell comprises introducing a mixture of N2and H2O comprising up to about 50% H2O.

12. An electrochemical cell, a positive electrode formulated to facilitate an oxidation reaction to produce H+, O2, and e- from H2O, the positive electrode comprising a first perovskite material and a support material, the support material comprising a second perovskite material exhibiting an ionic conductivity greater than or equal to about 10-2S / cm at one or more temperatures within a range of from about 350°C to about 700°C; a negative electrode formulated to facilitate a reduction reaction to produce NH3 from N2 and the H+; an electrolyte between the positive electrode and the negative electrode; and a power source configured to apply a potential difference between the positive electrode and the negative electrode.

13. The electrochemical cell of claim 12, wherein the negative electrode comprises a catalyst material formulated to accelerate the reduction reaction to produce the NH3from the N2and the H+, the catalyst material comprising one or more of Ru and an Ru alloy.

14. The electrochemical cell of claim 12, wherein the electrolyte comprises a proton-conducting membrane.

15. The electrochemical cell of claim 14, wherein the proton-conducting membrane comprises a perovskite material exhibiting a cubic lattice structure with a general formula ABO3-δ, wherein: A comprises barium (Ba); B comprises one or more of zirconium (Zr), cerium (Ce), yttrium (Y), and ytterbium (Yb); and ^ is an oxygen deficit.

16. A system for producing ammonia, comprising: a source of steam; a source of N2; an electrochemical apparatus in fluid communication with the source of steam and the source of N2, and comprising:a housing structure configured to receive a steam stream from the source of steam and to receive a N2stream from the source of N2; an electrochemical cell within an internal chamber of the housing structure, and comprising: a positive electrode formulated to facilitate an oxidation reaction to produce H+, O2, and e- from H2O; a negative electrode formulated to facilitate a reduction reaction to produce NH3from N2and the produced H+; and a proton-conducting membrane between the positive electrode and the negative electrode and comprising an electrolyte material having an ionic conductivity greater than or equal to about 10-2S / cm at one or more temperatures within a range of from about 350°C to about 700°C; and a power source configured to apply a potential difference between the positive electrode and the negative electrode.

17. The system of claim 16, further comprising: an outlet from the housing structure configured to receive a stream of O2 produced at the positive electrode; and an outlet from the housing structure configured to receive NH3 produced at the negative electrode.

18. The system of claim 16, wherein the internal chamber of the housing structure comprises a first chamber adjacent to the positive electrode and a second chamber adjacent to the negative electrode.

19. The system of claim 16, wherein the positive electrode comprises a first perovskite material and a support material, the support material comprising a second perovskite material.

20. The system of claim 19, wherein the second perovskite material comprises a material exhibiting an ionic conductivity greater than or equal to about 10-2S / cm at one or more temperatures within a range of from about 350°C to about 700°C.

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