Cathode electrode, and composite of cathode electrode and substrate

Abstract

The present disclosure provides a cathode electrode in which selectivity of hydrogen decreases and selectivity of a carbon dioxide reduction product increases in a catalytic reaction producing carbon monoxide, an olefinic hydrocarbon such as ethylene, and an alcohol such as ethanol by a reduction reaction of carbon dioxide. A cathode electrode that electrically reduces carbon dioxide, including: a first layer containing cuprous oxide, copper, and at least one additional metal element selected from the group consisting of silver, gold, zinc, cadmium, and tin; and a second layer formed on the first layer and containing a constituent element composed of at least one metal element selected from the group consisting of copper, silver, gold, zinc, cadmium, and tin.

What is claimed is: 
     
         1 . A cathode electrode that electrically reduces carbon dioxide, comprising:
 a first layer containing cuprous oxide, copper, and at least one additional metal element selected from the group consisting of silver, gold, zinc, cadmium, and tin; and   a second layer formed on at least a part of a region on the first layer and containing a constituent element composed of at least one metal element selected from the group consisting of copper, silver, gold, zinc, cadmium, and tin.   
     
     
         2 . A cathode electrode that electrically reduces carbon dioxide, comprising:
 a first layer containing cuprous oxide and at least one additional metal element selected from the group consisting of silver, gold, zinc, cadmium, and tin; and   a second layer formed on at least a part of a region on the first layer and containing a constituent element composed of at least one metal element selected from the group consisting of copper, silver, gold, zinc, cadmium, and tin.   
     
     
         3 . The cathode electrode according to  claim 2 , wherein a part of cuprous oxide in the first layer is reduced to copper by a reduction treatment. 
     
     
         4 . The cathode electrode according to  claim 1 , wherein the second layer is a protective layer for the first layer. 
     
     
         5 . The cathode electrode according to  claim 2 , wherein the second layer is a protective layer for the first layer. 
     
     
         6 . The cathode electrode according to  claim 1 , wherein the constituent element of the second layer contains a silver element. 
     
     
         7 . The cathode electrode according to  claim 2 , wherein the constituent element of the second layer contains a silver element. 
     
     
         8 . The cathode electrode according to  claim 6 , wherein the silver element as the constituent element is in a state of simple substance of silver or an oxide of silver. 
     
     
         9 . The cathode electrode according to  claim 7 , wherein the silver element as the constituent element is in a state of simple substance of silver or an oxide of silver. 
     
     
         10 . The cathode electrode according to  claim 1 , wherein the additional metal element of the first layer contains a zinc element. 
     
     
         11 . The cathode electrode according to  claim 2 , wherein the additional metal element of the first layer contains a zinc element. 
     
     
         12 . The cathode electrode according to  claim 1 , wherein a value of the number of moles of a copper element/the number of moles of an oxygen element in the first layer is 1.5 or more and 5.1 or less. 
     
     
         13 . The cathode electrode according to  claim 2 , wherein a value of the number of moles of a copper element/the number of moles of an oxygen element in the first layer is 1.5 or more and 5.1 or less. 
     
     
         14 . The cathode electrode according to  claim 1 , wherein the first layer has a porous structure. 
     
     
         15 . A composite of a cathode electrode and a substrate, comprising: a substrate having a porous structure; and the cathode electrode according to  claim 1  in which a side of the first layer is disposed on the substrate. 
     
     
         16 . The composite according to  claim 15 , wherein the substrate is porous carbon. 
     
     
         17 . An electrolytic reduction apparatus that electrically reduces carbon dioxide to carbon monoxide, an olefinic hydrocarbon, and/or an alcohol, comprising the cathode electrode according to  claim 1 . 
     
     
         18 . An electrolytic reduction apparatus that electrically reduces carbon dioxide to carbon monoxide, an olefinic hydrocarbon, and/or an alcohol, comprising the composite according to  claim 15 . 
     
     
         19 . A method of manufacturing a composite of a cathode electrode and a substrate, comprising:
 a step of providing a substrate having a porous structure;   a first coelectrodeposition layer forming step of coelectrodepositing cuprous oxide and at least one additional metal element selected from the group consisting of silver, gold, zinc, cadmium, and tin on the substrate to form a first coelectrodeposition layer that is a first layer; and   a second layer forming step of forming a film with a constituent element composed of at least one metal element selected from the group consisting of copper, silver, gold, zinc, cadmium, and tin to form a second layer on at least a part of a region on the first coelectrodeposition layer.   
     
     
         20 . The manufacturing method according to  claim 19 , further comprising a partial reduction step of partially reducing the first coelectrodeposition layer and the second layer after the second layer forming step.