Patent ID: 8414758

Claim:
A method for reducing carbon dioxide with use of a device for reducing carbon dioxide, the method comprising steps of: a step (a) of preparing the device for reducing carbon dioxide, wherein: the device comprises: a cathode chamber; an anode chamber; and a solid electrolyte membrane, the cathode chamber comprises a cathode electrode including a metal or a metal compound, the anode chamber comprises an anode electrode including a nitride semiconductor region on the surface thereof, a part of the surface of the nitride semiconductor region is covered with a nickel or titanium region, the nickel or titanium region is in contact with the nitride semiconductor region, a first electrolyte solution is held in the cathode chamber, a second electrolyte solution is held in the anode chamber, the cathode electrode is in contact with the first electrolyte solution, the anode electrode is in contact with the second electrolyte solution, the solid electrolyte membrane is interposed between the cathode chamber and the anode chamber, the first electrolyte solution contains the carbon dioxide, the cathode electrode is electrically connected to the anode electrode, a battery or a potentiostat as an external power supply is not electrically interposed between the cathode electrode and the anode electrode, the anode electrode comprises an anode electrode terminal for collecting electrons generated in the anode electrode, and the nickel or titanium region is apart from the anode electrode terminal; and a step (b) of irradiating at least part of the nitride semiconductor region on which the nickel or titanium region are formed with a light having a wavelength of 250 nanometers to 400 nanometers so as to cause a current to flow between the cathode electrode and the anode electrode and to reduce the carbon dioxide contained in the first electrolyte solution at the cathode electrode, the nickel or titanium region being irradiated with the light.