An electrolyzer for splitting molecular water into molecular hydrogen and molecular oxygen using electrical energy comprises an anodic half-cell with an anode and a cathodic half-cell with a cathode. The anodic half-cell and the cathodic half-cell are separated from each other by a separator. The anodic half-cell comprises an anodic electrolyte, which is in contact with the anode. The cathodic half-cell comprises a cathodic electrolyte, which is in contact with the cathode. The anodic half-cell comprises an anodic catalyst. The cathodic half-cell contains at least one cation complex for forming at least one mediator complex. The at least one cation complex is reducible to the mediator complex by taking up at least one electron at the cathode. The mediator complex is a catalytically active chemical complex for splitting the molecular water (H.sub.2O) into molecular hydrogen (H.sub.2) and hydroxide ions (OH.sup.−) while releasing at least one electron.

An electrolyzer for splitting molecular water into molecular hydrogen and molecular oxygen using electrical energy comprises an anodic half-cell with an anode and a cathodic half-cell with a cathode. The anodic half-cell and the cathodic half-cell are separated from each other by a separator. The anodic half-cell comprises an anodic electrolyte, which is in contact with the anode. The cathodic half-cell comprises a cathodic electrolyte, which is in contact with the cathode. The anodic half-cell comprises an anodic catalyst. The cathodic half-cell contains at least one cation complex for forming at least one mediator complex. The at least one cation complex is reducible to the mediator complex by taking up at least one electron at the cathode. The mediator complex is a catalytically active chemical complex for splitting the molecular water (H.sub.2O) into molecular hydrogen (H.sub.2) and hydroxide ions (OH.sup.−) while releasing at least one electron.

A method of synthesizing a three-dimensional (3D) reduced graphene oxide (RGO) foam embedded with water-splitting nanocatalysts includes providing at least one solution containing at least one precursor of nanocatalysts, and a graphene oxide (GO) aqueous suspension; mixing the GO aqueous suspension with the at least one solution to form a mixture suspension; and performing hydrothermal reaction in the mixture suspension to form a 3D RGO foam embedded with the nanocatalysts.

A method of synthesizing a three-dimensional (3D) reduced graphene oxide (RGO) foam embedded with water-splitting nanocatalysts includes providing at least one solution containing at least one precursor of nanocatalysts, and a graphene oxide (GO) aqueous suspension; mixing the GO aqueous suspension with the at least one solution to form a mixture suspension; and performing hydrothermal reaction in the mixture suspension to form a 3D RGO foam embedded with the nanocatalysts.

A carbon dioxide reduction device of the present invention is a carbon dioxide reduction device comprising a first electrode; at least any one of an electrolyte solution and an ion conducting membrane; and a second electrode, wherein the first electrode is a porous electrode having a porous carbon, and the porous carbon has at least one type of metal-nonmetal element bond represented by M-R, in which M represents a metal element of Groups 4 to 15, and R represents a nonmetal element of Groups 14 to 16.

A carbon dioxide reduction device of the present invention is a carbon dioxide reduction device comprising a first electrode; at least any one of an electrolyte solution and an ion conducting membrane; and a second electrode, wherein the first electrode is a porous electrode having a porous carbon, and the porous carbon has at least one type of metal-nonmetal element bond represented by M-R, in which M represents a metal element of Groups 4 to 15, and R represents a nonmetal element of Groups 14 to 16.

A porous solid electrolyte electrosynthesis cell and corresponding related process for the direct synthesis of high purity liquid products wherein the electrosynthesis cell comprises a cathode compartment including a cathode electrode comprising a gas diffusion layer loaded with a selective reduction reaction electrocatalyst for specific reduction reactions. The electrosynthesis cell further includes an anode compartment including an anode electrode comprising a gas diffusion layer loaded with a catalyst for oxidation reactions; and a solid electrolyte compartment comprising a porous solid electrolyte; a cation exchange membrane; and an anion exchange membrane; (or two cation exchange membranes) wherein the solid electrolyte compartment is separated from the cathode and the anode by the anion exchange membrane and the cation exchange membrane (or by the two cation exchange membranes).

In an anode side electrolytic domain (130), a radial flow is formed from an outer peripheral opening (131) to an inner side opening (141) of an anode side mesh electrode (140). Flows horizontal to the electrode surface of the anode side mesh electrode 140 are formed. Gases such as ozone generated from water electrolysis in the anode side electrolytic domain (130) are dissolved in raw water in the anode side electrolytic domain (130), and anode side electrolytic water is generated. Gas such as ozone that has been atomized by the anode side mesh electrode (140) comes into contact with the raw water, and high concentration anode side electrolytic water is generated. The anode side electrolytic water generated in the anode side electrolytic domain (130) flows in the inner side opening (141) of the anode side mesh electrode (140).

In an anode side electrolytic domain (130), a radial flow is formed from an outer peripheral opening (131) to an inner side opening (141) of an anode side mesh electrode (140). Flows horizontal to the electrode surface of the anode side mesh electrode 140 are formed. Gases such as ozone generated from water electrolysis in the anode side electrolytic domain (130) are dissolved in raw water in the anode side electrolytic domain (130), and anode side electrolytic water is generated. Gas such as ozone that has been atomized by the anode side mesh electrode (140) comes into contact with the raw water, and high concentration anode side electrolytic water is generated. The anode side electrolytic water generated in the anode side electrolytic domain (130) flows in the inner side opening (141) of the anode side mesh electrode (140).

The present invention relates to a graphene material inlaid with single metal atoms, the preparation method thereof and its application of being used as the catalyst for the electroreduction of carbon dioxide. The graphene material inlaid with single metal atoms comprises single metal atoms and graphene; the single metal atoms are dispersed in the framework of the graphene; and the graphene is at least one selected from N doped graphene and N and S co-doped graphene. The material is used for the electrochemical reduction reaction of carbon dioxide, which significantly improves the utilization efficiency of the metal atoms and enhances the catalytic activity for the electroreduction of carbon dioxide, improves the catalytic stability, inhibits effectively the hydrogen evolution reaction, improves the selectivity for CO product, and broadens the electric potential window of reducing carbon dioxide to generate CO.