Abstract: An optical device includes an intermetallic compound of a first metal and a second metal having a lower work function than the first metal, or a solid-solution alloy of the first metal and the second metal and includes an n-type semiconductor in Schottky junction with the intermetallic compound or the solid-solution alloy.

Abstract: An optical device includes an intermetallic compound of a first metal and a second metal having a lower work function than the first metal, or a solid-solution alloy of the first metal and the second metal and includes an n-type semiconductor in Schottky junction with the intermetallic compound or the solid-solution alloy.

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: The present invention provides a method for reducing carbon dioxide electrochemically to generate ethylene selectively. In the present method, a carbon dioxide reduction catalyst comprising a crystalline copper phthalocyanine is used to generate ethylene selectively by reducing carbon dioxide electrochemically on a cathode electrode.

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: 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 disclosure provides a fuel production method and a fuel production apparatus which efficiently convert solar light energy into a fuel. The fuel production apparatus of the present disclosure includes a laminate, an electrolytic bath, and a support tool or a proton permeable membrane. The laminate includes a photoelectromotive layer having a p-n junction structure, a cathode electrode, an anode electrode and a side surface insulating layer, and the photoelectromotive layer includes a semiconductor layer that absorbs light in a near-infrared region with a wavelength of 900 nm or more.

Abstract: The present disclosure provides an electrode for an electrolysis device, which allows performance of a catalyst to be efficiently exhibited in an electrochemical reaction of reducing an electrolysis reactant to generate an electrolysis product material. Specifically, a carbon fiber that has a structure in which the carbon fiber contains a part of and/or a whole of a catalyst particle is used as a cathode electrode to greatly improve adherence force of the catalyst particle and enable efficient generation of an electrolysis product material.

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: 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 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: 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: 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: 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 disclosure provides a light concentrating device for a photochemical reaction device capable of decreasing abnormal chemical reactions that occur when intensity of sunlight is too strong for an electrode of a photochemical reaction device. The light concentrating device includes a lens for concentrating sunlight on the electrode of the photochemical reaction device, a lens movement device for moving the lens in an optical axis direction, an image pickup device for picking up an image of transmitted sunlight that passes through the electrode, an abnormal chemical reaction detector for detecting presence of an abnormal chemical reaction on the electrode based on information on the image picked up by the image pickup device, and a lens position controller for controlling the lens movement device to move the lens to decrease occurrence of the abnormal chemical reaction when the abnormal chemical reaction detector detects the abnormal chemical reaction.

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.