Some embodiments of the present invention provide solid oxide cells and components thereof having a metal oxide electrolyte that exhibits enhanced ionic conductivity. Certain of those embodiments have two materials, at least one of which is a metal oxide, disposed so that at least some interfaces between the domains of the materials orient in a direction substantially parallel to the desired ionic conductivity.

Described herein are salt-splitting electrolysis systems, which comprise flow electrodes, and methods of operating such systems. Specifically, the flow electrodes comprise active particles (suspended in a solvent) with catalysts. These catalysts are configured to react with either cations or anions, provided in a feed stream. The flow electrodes allow using the same system for different feed streams, e.g., by flowing different types of electrodes through the system. Furthermore, the flow electrodes allow in-situ catalyst reconditioning. For example, the active particles can be flown from the current collectors to respective recovery devices where the particles are discharged or subjected to a reverse potential. The active particles can be conductive and provide more desirable electrical field distribution between the current collectors resulting in greater ionic mobility. Finally, the active particles concentrate ions around the particles thereby providing a higher concentration gradient through separating structures, which enclose the feed stream.

Described herein are salt-splitting electrolysis systems, which comprise flow electrodes, and methods of operating such systems. Specifically, the flow electrodes comprise active particles (suspended in a solvent) with catalysts. These catalysts are configured to react with either cations or anions, provided in a feed stream. The flow electrodes allow using the same system for different feed streams, e.g., by flowing different types of electrodes through the system. Furthermore, the flow electrodes allow in-situ catalyst reconditioning. For example, the active particles can be flown from the current collectors to respective recovery devices where the particles are discharged or subjected to a reverse potential. The active particles can be conductive and provide more desirable electrical field distribution between the current collectors resulting in greater ionic mobility. Finally, the active particles concentrate ions around the particles thereby providing a higher concentration gradient through separating structures, which enclose the feed stream.

A light-driven fuel cell includes a cathode, an anode, and a proton-permeable membrane between the anode and the cathode. The anode includes a photocatalyst for anaerobic methane oxidation reaction, and when the anode is supplied with methane and water and is irradiated with light, methanol, protons and electrons are generated by anaerobic methane oxidation reaction from the methane and the water supplied to the anode; the protons pass through the proton-permeable membrane and move to the cathode; and the electrons move to the cathode via an external circuit. The cathode includes a photocatalyst for aerobic methane oxidation reaction, and when the cathode is supplied with methane and oxygen and is irradiated with light, methanol and water are generated by aerobic methane oxidation reaction from the methane and the oxygen supplied to the cathode and the protons and the electrons moved from the anode.

A light-driven fuel cell includes a cathode, an anode, and a proton-permeable membrane between the anode and the cathode. The anode includes a photocatalyst for anaerobic methane oxidation reaction, and when the anode is supplied with methane and water and is irradiated with light, methanol, protons and electrons are generated by anaerobic methane oxidation reaction from the methane and the water supplied to the anode; the protons pass through the proton-permeable membrane and move to the cathode; and the electrons move to the cathode via an external circuit. The cathode includes a photocatalyst for aerobic methane oxidation reaction, and when the cathode is supplied with methane and oxygen and is irradiated with light, methanol and water are generated by aerobic methane oxidation reaction from the methane and the oxygen supplied to the cathode and the protons and the electrons moved from the anode.

To provide a membrane electrode assembly, a solid polymer electrolyte membrane, a water electrolysis apparatus, and an electrolytic hydrogenation apparatus, that can reduce the range of increase in electrolysis voltage even when the current density increases when applied to a water electrolysis apparatus or an electrolytic hydrogenation apparatus. The membrane electrode assembly of the present invention comprises an anode having a catalyst layer, a cathode having a catalyst layer, and a solid polymer electrolyte membrane disposed between the anode and the cathode, wherein the solid polymer electrolyte membrane comprises a fluorinated polymer having ion-exchange groups and a woven fabric, wherein the aperture ratio of the woven fabric is at least 50%, and the ratio TA.sub.AVE/TB.sub.AVE calculated from the average maximum membrane thickness TA.sub.AVE and the average minimum membrane thickness TB.sub.AVE of the solid polymer electrolyte membrane is at least 1.20.

Methods, apparatuses, and systems related to the electrochemical separation of target gases from gas mixtures are provided. In some cases, a target gas such as carbon dioxide is captured and optionally released using an electrochemical cell (e.g., by bonding to an electroactive species in a reduced state). Some embodiments are particularly useful for selectively capturing the target gas while reacting with little to no oxygen gas that may be present in the gas mixture. Some such embodiments may be useful in applications involving separations from gas mixtures having relatively low concentrations of the target gas, such as direct air capture and ventilated air treatment.

Methods, apparatuses, and systems related to the electrochemical separation of target gases from gas mixtures are provided. In some cases, a target gas such as carbon dioxide is captured and optionally released using an electrochemical cell (e.g., by bonding to an electroactive species in a reduced state). Some embodiments are particularly useful for selectively capturing the target gas while reacting with little to no oxygen gas that may be present in the gas mixture. Some such embodiments may be useful in applications involving separations from gas mixtures having relatively low concentrations of the target gas, such as direct air capture and ventilated air treatment.

A method of carbon dioxide hydrogenation comprises introducing gaseous water to a positive electrode of an electrolysis cell comprising the positive electrode, a negative electrode, 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.sup.−2 S/cm at one or more temperatures within a range of from about 150° C. to about 650° C. Carbon dioxide is introduced to the negative electrode of the electrolysis cell. A potential difference is applied between the positive electrode and the negative electrode of the electrolysis cell to generate hydrogen ions from the gaseous water that diffuses through the proton-conducting membrane and hydrogenates the carbon dioxide at the negative electrode. A carbon dioxide hydrogenation system is also described.

A method of carbon dioxide hydrogenation comprises introducing gaseous water to a positive electrode of an electrolysis cell comprising the positive electrode, a negative electrode, 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.sup.−2 S/cm at one or more temperatures within a range of from about 150° C. to about 650° C. Carbon dioxide is introduced to the negative electrode of the electrolysis cell. A potential difference is applied between the positive electrode and the negative electrode of the electrolysis cell to generate hydrogen ions from the gaseous water that diffuses through the proton-conducting membrane and hydrogenates the carbon dioxide at the negative electrode. A carbon dioxide hydrogenation system is also described.