Abstract: Disclosed is an anode electrode including a nitride semiconductor layer. This nitride semiconductor layer includes an AlxGa1-xN layer (0<x?0.25), an AlyGa1-yN layer (0?y?x), and a GaN layer. The AlyGa1-yN layer is interposed between the AlxGa1-xN layer and the GaN layer. The value of x is fixed in the thickness direction of the AlxGa1-xN layer. The value of y decreases from the interface with the AlxGa1-xN layer f toward the interface with the GaN layer. The AlxGa1-xN layer is irradiated with light having a wavelength of 360 nm or less so as to reduce carbon dioxide.

Abstract: The present invention provides a method for splitting water. In the present method, first, prepared is a water splitting device comprising: cathode and anode containers in which first and second electrolyte solutions are stored respectively; a proton exchange membrane disposed therebetween; a cathode electrode in contact with the first electrolyte solution and comprises a metal or metal compound; and an anode electrode in contact with the second electrolyte solution and comprises a nitride semiconductor layer. Then, the anode electrode is irradiated with light to split water contained in the first electrolyte solution. The anode electrode comprises a cobalt oxide layer formed of Co3O4 as a main component on a surface of the nitride semiconductor layer; the surface of the nitride semiconductor layer being in contact with the second electrolyte solution. The cathode electrode is electrically connected to the anode electrode without an external power supply.

Abstract: In a method for generating formic acid by reducing carbon dioxide, a formic acid generation apparatus is prepared. The apparatus includes: a cathode container for storing a first electrolyte solution containing carbon dioxide; an anode container for storing a second electrolyte solution; a solid electrolyte membrane sandwiched between the cathode and anode containers; a cathode electrode provided in the cathode container in contact with the first electrolyte solution, the cathode electrode having a gallium oxide region on a surface thereof; an anode electrode provided in the anode container in contact with the second electrolyte solution; and an external power supply for applying a negative voltage and a positive voltage to the cathode electrode and the anode electrode, respectively. A negative voltage and a positive voltage are applied to the cathode electrode and the anode electrode, respectively, using the external power supply to generate formic acid on the cathode electrode.

Abstract: A method for reducing carbon dioxide is provided. In the present method, used is an anode electrode comprises a stacked structure of a photoelectric conversion layer, a metal layer, and an InxGa1-xN layer (where 0<x?1). The InxGa1-xN layer is of i-type or n-type. The metal layer is interposed between the photoelectric conversion layer and the InxGa1-xN layer. When irradiating the anode electrode with light, a first light part included in the light is absorbed by the InxGa1-xN layer and a second light part included in the light travels through the InxGa1-xN layer. The second light part is absorbed by the photoelectric conversion layer to generate electric power in the photoelectric conversion layer. The second light part has a longer wavelength than the first light part. The carbon dioxide contained in the first electrolyte solution is reduced on the cathode electrode.

Abstract: In a carbon dioxide reduction method according to the present disclose, used is a carbon dioxide reduction device comprising a cathode container in which a first electrolyte containing carbon dioxide is stored, an anode container in which a second electrolyte is stored, a solid electrolyte membrane, a condenser, a cathode electrode having a metal or a metal compound on the surface thereof, and anode electrode having a region formed of a nitride semiconductor layer in which a GaN layer and an AlxGa1-xN layer are stacked. The anode electrode is irradiated with light condensed by the condenser and having a wavelength of not more than 360 nanometers to reduce the carbon dioxide contained in the first electrolyte on the cathode electrode.

Abstract: Disclosed is a method for producing an alcohol using a device for reducing carbon dioxide by light energy. In this device, a cathode electrode includes copper or a copper compound, and an anode electrode includes a region including a nitride semiconductor layer in which an AlxGa1-xN layer (0<x?1) and a GaN layer are laminated. A first electrolytic solution consisting of an aqueous potassium chloride solution (aqueous KCl solution) is contained in a cathode chamber in which the cathode electrode is placed. A second electrolytic solution including an aqueous sodium hydroxide solution (aqueous NaOH solution) is contained in an anode chamber in which the anode electrode is placed.

Abstract: A device for reducing CO2 by light, including: a cathode chamber holding a first electrolyte solution that contains CO2; an anode chamber holding a second electrolyte solution; a proton conducting membrane disposed in a connecting portion between these chambers; a cathode electrode; and an anode electrode. The cathode electrode has a CO2 reduction reaction region composed of a metal or a metal compound, and the anode electrode has a photochemical reaction region composed of nitride semiconductors. The photochemical reaction region of the anode electrode has a multilayer structure of a GaN layer and an AlxGa1-xN layer containing Mg (0<x?0.25). The content of Mg in the AlxGa1-xN layer is 1×1015 or more and 1×1019 or less in terms of the number of Mg atom per cm3. The anode electrode is disposed in such a manner that the AlxGa1-xN layer can be exposed to light.

Abstract: The present invention provides a formic acid generation apparatus for generating formic acid by reducing carbon dioxide, comprising: a cathode container for storing a first electrolyte solution containing carbon dioxide; an anode container for storing a second electrolyte solution; a solid electrolyte membrane sandwiched between the cathode container and the anode container; a cathode electrode provided in the cathode container so as to be in contact with the first electrolyte solution, the cathode electrode having a gallium oxide region on a surface thereof; an anode electrode provided in the anode container so as to be in contact with the second electrolyte solution; and an external power supply for applying a negative voltage and a positive voltage to the cathode electrode and the anode electrode, respectively.

Abstract: The present invention provides a methanol generation device for generating methanol by reducing carbon dioxide, comprising: a container for storing an electrolyte solution containing carbon dioxide; a cathode electrode disposed in the container so as to be in contact with the electrolyte solution; an anode electrode disposed in the container so as to be in contact with the electrolyte solution; and an external power supply for applying a voltage so that a potential of the cathode electrode is negative with respect to a potential of the anode electrode. The cathode electrode has a region of Cu1-x-yNixAuy (0<x, 0<y, and x+y<1). The anode electrode has a region of a metal or a metal compound.

Abstract: The present invention provides a methanol generation device for generating methanol by reducing carbon dioxide, comprising: a container for storing an electrolyte solution containing carbon dioxide; a cathode electrode disposed in the container so as to be in contact with the electrolyte solution; an anode electrode disposed in the container so as to be in contact with the electrolyte solution; and an external power supply for applying a voltage so that a potential of the cathode electrode is negative with respect to a potential of the anode electrode. The cathode electrode includes a region of Cu1-xAux (0<x<1). The anode electrode includes a region of a metal or a metal compound.

Abstract: Provided is a biogas generation system comprising a fermenter for generating a biogas containing carbon dioxide and methane by decomposing an organic waste by the action of methane bacteria; a biogas refinery for condensing the methane contained in the biogas by dissolving the carbon dioxide contained in the generated biogas in a liquid; and a photoelectrochemical device for generating methane, carbon monoixide, or formic acid from the carbon dioxide dissolved in the liquid. The photoelectrochemical device comprises a cathode chamber for storing a first electrolyte solution containing the carbon dioxide dissolved in the liquid; an anode chamber for storing a second electrolyte solution; a solid electrolyte membrane; a cathode electrode provided in the cathode chamber; an anode electrode provided in the anode chamber; and an external power supply for applying a negative voltage and a positive voltage to the cathode electrode and the anode electrode, respectively.

Abstract: Disclosed is a method for producing an alcohol using a device for reducing carbon dioxide by light energy. In this device, a cathode electrode includes copper or a copper compound, and an anode electrode includes a region including a nitride semiconductor layer in which an AlxGa1-xN layer (0<x?1) and a GaN layer are laminated. A first electrolytic solution consisting of an aqueous potassium chloride solution (aqueous KCl solution) is contained in a cathode chamber in which the cathode electrode is placed. A second electrolytic solution including an aqueous sodium hydroxide solution (aqueous NaOH solution) is contained in an anode chamber in which the anode electrode is placed.

Abstract: Disclosed is an anode electrode including a nitride semiconductor layer. This nitride semiconductor layer includes an AlxGa1-xN layer (0<x?0.25), an AlyGa1-yN layer (0?y?x), and a GaN layer. The AlyGa1-yN layer is interposed between the AlxGa1-xN layer and the GaN layer. The value of x is fixed in the thickness direction of the AlxGa1-xN layer. The value of y decreases from the interface with the AlxGa1-xN layer f toward the interface with the GaN layer. The AlxGa1-xN layer is irradiated with light having a wavelength of 360 nm or less so as to reduce carbon dioxide.

Abstract: The carbon dioxide reducing method using light includes: (a) preparing a carbon dioxide reducing cell including: a cathode chamber that holds first electrolytic solution containing carbon dioxide; an anode chamber that holds second electrolytic solution; a proton exchange membrane inserted between the cathode and anode chambers; a cathode set inside the cathode chamber to contact the first electrolytic solution, and the cathode having copper, gold, silver, indium, etc. on the cathode; and an anode set inside the anode chamber to contact the second electrolytic solution, the anode having first semiconductor layer constituted by nitride semiconductor including AlxGa1-xN layer wherein 0?x?0.

Abstract: A method for reducing carbon dioxide utilizes a carbon dioxide reduction device including a cathode chamber, an anode chamber, a solid electrolyte membrane, a cathode electrode and anode electrode. The cathode electrode includes copper or copper compound. The anode electrode includes a region formed of a nitride semiconductor layer where an AlxGa1-xN (0<x?1) layer and a GaN layer are stacked. The anode electrode is irradiated with a light having a wavelength of not more than 350 nanometers to reduce the carbon dioxide on the cathode electrode.

Abstract: A method for reducing carbon dioxide utilizes a carbon dioxide reduction device including a cathode chamber, an anode chamber, a solid electrolyte membrane, a cathode electrode and anode electrode. The cathode electrode includes indium or indium compound. The anode electrode includes a region formed of a nitride semiconductor layer where an AlxGa1-xN (0<x?1) layer and a GaN layer are stacked. The anode electrode is irradiated with a light having a wavelength of not more than 350 nanometers to reduce the carbon dioxide on the cathode electrode.

Abstract: The present subject matter provides a method for reducing carbon dioxide with the use of a device for reducing carbon dioxide. The device includes a cathode chamber, an anode chamber and a solid electrolyte membrane. The cathode chamber includes a working electrode which includes a metal or a metal compound. The anode chamber includes a counter electrode which includes a region formed of a nitride semiconductor. First and second electrolytic solutions are held in the cathode and anode chamber, respectively. The working electrode and the counter electrode are in contact with the first and second electrolytic solution, respectively. The solid electrolyte membrane is interposed between the cathode and anode chambers. The first electrolyte solution contains the carbon dioxide. An electric source is not interposed electrically between the working electrode and the counter electrode.

Abstract: The method for reducing carbon dioxide of the present invention includes a step (a) and a step (b) as follows. A step (a) of preparing an electrochemical cell. The electrochemical cell comprises a working electrode (21), a counter electrode (23) and a vessel (28). The vessel (28) stores an electrolytic solution (27). The working electrode (21) contains boron carbide. The electrolytic solution (27) contains carbon dioxide. The working electrode (21) and the counter electrode (23) are in contact with the electrolytic solution (27). A step (b) of applying a negative voltage and a positive voltage to the working electrode and the counter electrode, respectively, to reduce the carbon dioxide.

Abstract: The method for reducing carbon dioxide of the present disclosure includes a step (a) and a step (b) as follows. A step (a) of preparing an electrochemical cell. The electrochemical cell comprises a working electrode, a counter electrode and a vessel. The vessel stores an electrolytic solution. The working electrode contains at least one nitride selected from the group consisting of titanium nitride, zirconium nitride, hafnium nitride, tantalum nitride, molybdenum nitride and iron nitride. The electrolytic solution contains carbon dioxide. The working electrode and the counter electrode are in contact with the electrolytic solution. A step (b) of applying a negative voltage and a positive voltage to the working electrode and the counter electrode, respectively, to reduce the carbon dioxide.

Abstract: A device for reducing carbon dioxide includes a cathode chamber including a cathode electrolyte solution and a cathode electrode, an anode chamber including an anode electrolyte solution and an anode electrode, and a solid electrolyte membrane. The anode electrode includes a nitride semiconductor region on which a metal layer is formed. The metal layer includes at least one of nickel and titanium. A method for reducing carbon dioxide by using a device for reducing carbon dioxide includes steps of providing carbon dioxide into the cathode solution, and irradiating at least part of the nitride semiconductor region and the metal layer with a light having a wavelength of 250 nanometers to 400 nanometers, thereby reducing the carbon dioxide contained in the cathode electrolyte solution.