Hydrogen gas as a power source is obtained from gaseous water, including seawater vapor existing abundantly at near-surface levels of the oceans or humid air over land. An integrated system of photovoltaic cells for capturing and harnessing solar energy is combined with a water vapor electrolysis system comprising an electrolyzer with an anode compartment and a cathode compartment separated by a proton exchange membrane. The photovoltaic aspects of the system convert the energy of the sun to drive electrolysis of gaseous water from the environment. The electrolyzer aspects include an anode, a cathode, and a proton exchange membrane. At the anode, oxygen evolution reaction (OER) catalysts oxidize H.sub.2O to oxygen gas and protons, the latter being diffused through a membrane (e.g., a solid polymer electrolyte membrane such as Nafion). At the cathode, photogenerated electrons are conducted to hydrogen evolution reaction (HER) catalysts to reduce the protons to hydrogen gas, while concentration gradients drive the generated O.sub.2 back to the atmosphere.

The application relates to a process for operating in starting mode or in stand-by mode a unit, termed power-to-gas unit, comprising a number N of reactors (1) with a stack of elemental electrolysis cells of solid oxide type (SOEC), the cathodes of which are made of methanation reaction catalyst material(s).

The application relates to a process for operating in starting mode or in stand-by mode a unit, termed power-to-gas unit, comprising a number N of reactors (1) with a stack of elemental electrolysis cells of solid oxide type (SOEC), the cathodes of which are made of methanation reaction catalyst material(s).

A method of electrochemically reducing CO.sub.2 to form at least one alcohol, preferably ethanol. The method includes (a) contacting an electrode system with an aqueous solution comprising at least one electrolyte and CO.sub.2, wherein the electrode system comprises a working electrode, a counter electrode, and a reference electrode, wherein the working electrode comprises a base electrode and a coating of a composite comprising graphene nanosheets and Cu.sub.2O nanoparticles disposed on a surface of the base electrode, and (b) applying a negative potential to the working electrode to reduce the CO.sub.2 and form the at least one alcohol.

Features for an aqueous reactor include a field generator. The field generator includes a series of parallel conductive plates including a series of intermediate neutral plates. The intermediate neutral plates are arranged in interleaved sets between an anode and a cathode. Other features of the aqueous reactor may include a sealed reaction vessel, fluid circulation manifold, electrical power modulator, vacuum port, and barrier membrane. Methods of using the field generator include immersion in an electrolyte solution and application of an external voltage and vacuum to generate hydrogen and oxygen gases. The reactor and related components can be arranged to produce gaseous fuel or liquid fuel. In one use, a mixture of a carbon based material and a liquid hydrocarbon is added. The preferred carbon based material is powdered coal.

Features for an aqueous reactor include a field generator. The field generator includes a series of parallel conductive plates including a series of intermediate neutral plates. The intermediate neutral plates are arranged in interleaved sets between an anode and a cathode. Other features of the aqueous reactor may include a sealed reaction vessel, fluid circulation manifold, electrical power modulator, vacuum port, and barrier membrane. Methods of using the field generator include immersion in an electrolyte solution and application of an external voltage and vacuum to generate hydrogen and oxygen gases. The reactor and related components can be arranged to produce gaseous fuel or liquid fuel. In one use, a mixture of a carbon based material and a liquid hydrocarbon is added. The preferred carbon based material is powdered coal.

Disclosed is a method to color tune an electrochromic device by the use of a standard dye. By following the subtractive color mixing theory and selecting the appropriate standard dye to compliment or accentuate the electrochromic material, tuning of the optical and colorimetric properties of the resulting electrochromic device can be achieved. The method can also be used to prepare electrochromic devices that will switch between two neutral colors.

Disclosed is a method to color tune an electrochromic device by the use of a standard dye. By following the subtractive color mixing theory and selecting the appropriate standard dye to compliment or accentuate the electrochromic material, tuning of the optical and colorimetric properties of the resulting electrochromic device can be achieved. The method can also be used to prepare electrochromic devices that will switch between two neutral colors.

A method of forming a hydrocarbon product and hydrogen gas comprises introducing CH.sub.4 to a positive electrode of an electrochemical 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 600? C. A potential difference is applied between the positive electrode and the negative electrode of the electrochemical cell to produce the hydrocarbon product and the hydrogen gas. A CH.sub.4 activation system and an electrochemical cell are also described.

A method of forming a hydrocarbon product and hydrogen gas comprises introducing CH.sub.4 to a positive electrode of an electrochemical 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 600? C. A potential difference is applied between the positive electrode and the negative electrode of the electrochemical cell to produce the hydrocarbon product and the hydrogen gas. A CH.sub.4 activation system and an electrochemical cell are also described.