Photochemical reaction device

Abstract

The present invention provides: an oxidation reaction electrode that generates oxygen by oxidizing water; and a reduction reaction electrode that synthesizes a carbon compound by reducing carbon dioxide. The two electrodes are electrically connected. Also, the reduction reaction electrode ( 1 ) synthesizes a carbon compound by reducing carbon dioxide in a water-containing liquid using radiated light energy.

1 . A photochemical reaction device comprising:
 an oxidation reaction electrode which oxidizes water and generates oxygen; and   a reduction reaction electrode which reduces carbon dioxide and synthesizes a carbon compound, wherein   the oxidation reaction electrode and the reduction reaction electrode are electrically connected, and   the reduction reaction electrode reduces carbon dioxide and synthesizes the carbon compound in a solution containing water, by means of energy of irradiated light.   
     
     
         2 . The photochemical reaction device according to  claim 1 , wherein
 an energy level of a conduction band minimum of the oxidation reaction electrode is positioned at a potential on a negative side with respect to an energy level of a valance band minimum of the reduction reaction electrode.   
     
     
         3 . The photochemical reaction device according to  claim 1 , wherein
 the reduction reaction electrode has a structure in which a semiconductor electrode and a catalyst which presents a reduction action of carbon dioxide are coupled, and   the reduction reaction of carbon dioxide is presented by movement of excited electrons generated by radiation of light on the semiconductor electrode to the catalyst.   
     
     
         4 . The photochemical reaction device according to  claim 1 , wherein
 the reduction reaction electrode has a structure in which a semiconductor electrode and a catalyst which presents a reduction action of carbon dioxide are coupled by chemical polymerization, and   the reduction reaction electrode reduces carbon dioxide and synthesizes the carbon compound in the solution containing water by means of the energy of irradiated light.   
     
     
         5 . The photochemical reaction device according to  claim 1 , wherein
 the oxidation reaction electrode and the reduction reaction electrode are placed in two chambers separated by a proton exchange membrane, and the oxidation reaction electrode and the reduction reaction electrode are electrically connected, and   the reduction reaction electrode reduces carbon dioxide and synthesizes the carbon compound in the solution containing water by means of the energy of irradiated light.   
     
     
         6 . The photochemical reaction device according to  claim 1 , wherein
 the oxidation reaction electrode and the reduction reaction electrode are electrically connected,   the oxidation reaction electrode is a semiconductor electrode, and oxidizes water and extracts electrons by means of the energy of irradiated light, and   the reduction reaction electrode reduces carbon dioxide and synthesizes the carbon compound in the solution containing water by means of the energy of irradiated light.   
     
     
         7 . The photochemical reaction device according to  claim 3 , wherein
 the catalyst is a metal complex or a polymer thereof.   
     
     
         8 . The photochemical reaction device according to  claim 7 , wherein
 the catalyst is a mixture of a first metal complex having an anchor site which is connected to the semiconductor electrode and a second metal complex which is polymerized with the first metal complex and which has a catalytic function.   
     
     
         9 . The photochemical reaction device according to  claim 8 , wherein
 the second metal complex has a pyrrole site.   
     
     
         10 . The photochemical reaction device according to  claim 8 , wherein
 a chemical polymerization film of the first metal complex and the second metal complex is formed on a surface of the semiconductor electrode.   
     
     
         11 . The photochemical reaction device according to  claim 1 , wherein
 the oxidation reaction electrode and the reduction reaction electrode are directly connected in a state where no external bias voltage is applied, and light is irradiated on both electrodes so that water functions as an electron donor for CO 2  reduction.   
     
     
         12 . The photochemical reaction device according to  claim 1 , wherein
 the oxidation reaction electrode and the reduction reaction electrode are connected in a state where a bias power supply is applied, and light is irradiated on both electrodes so that water functions as an electron donor.   
     
     
         13 . The photochemical reaction device according to  claim 1 , wherein
 the oxidation reaction electrode comprises titanium oxide.   
     
     
         14 . The photochemical reaction device according to  claim 13 , wherein
 the oxidation reaction electrode comprises anatase-type titanium oxide.   
     
     
         15 . The photochemical reaction device according to  claim 1 , wherein
 the solution containing water is water or an aqueous solution containing an electrolyte.   
     
     
         16 . The photochemical reaction device according to  claim 1 , wherein
 the oxidation reaction electrode and the reduction reaction electrode are separated by an ion exchange membrane.   
     
     
         17 . The photochemical reaction device according to  claim 1 , wherein
 a three-electrode system structure is employed which has a reference electrode in addition to the oxidation reaction electrode and the reduction reaction electrode.   
     
     
         18 . A composite photoelectrode comprising:
 a catalyst which presents a reduction reaction of carbon dioxide, and   a semiconductor electrode coupled with the catalyst, wherein   the reduction reaction of carbon dioxide is presented by transfer to the catalyst of excited electrons generated by radiation of light on the semiconductor electrode.   
     
     
         19 . The composite photoelectrode according to  claim 18 , wherein
 the catalyst is a metal complex or a polymer thereof.   
     
     
         20 . The composite photoelectrode according to  claim 18 , wherein
 the semiconductor electrode is a sulfide semiconductor or a phosphide semiconductor.   
     
     
         21 . A light energy storage device in which the composite photoelectrode according to  claim 18  and an oxidation reaction electrode which oxidizes water and generates oxygen are connected.