Gas diffusion electrode suitable for use in carbon dioxide electrolyzer and membrane electrode assembly including said gas diffusion electrode

Abstract

Gas diffusion electrode suitable for use in a carbon dioxide electrolyzer and membrane electrode assembly including same. In one embodiment, the gas diffusion electrode may include a gas diffusion layer and a catalyst layer. The gas diffusion layer may be a porous, hydrophobic structure. The gas diffusion layer may have a set of pores designed for gas transport through the gas diffusion layer and may also have a set of openings designed for water drainage and/or water pressure relief. The gas transport pores are smaller in size than the water drainage openings. The catalyst layer may be positioned on a side of the gas diffusion layer and preferably does not cover the openings designed for water drainage and/or water pressure relief. The gas diffusion layer may or may not be electron-conductive. If the gas diffusion layer is non-conductive, the gas diffusion electrode may further include an electron conductive layer.

What is claimed is: 
     
         1 . A gas diffusion electrode suitable for use in a carbon dioxide electrolyzer, the gas diffusion electrode comprising:
 (a) a gas diffusion layer, the gas diffusion layer comprising a porous hydrophobic structure having a pair of opposing sides, the gas diffusion layer comprising a set of one or more pores designed for gas transport through the gas diffusion layer and a set of one or more openings designed for water drainage through the gas diffusion layer, wherein the one or more pores are comparatively smaller in size and the one or more openings are comparatively larger in size; and   (b) a catalyst layer, the catalyst layer being disposed on one of the pair of opposing sides.   
     
     
         2 . The gas diffusion electrode as claimed in  claim 1  wherein the catalyst layer does not cover the one or more openings of the gas diffusion layer. 
     
     
         3 . The gas diffusion electrode as claimed in  claim 1  wherein the gas diffusion layer is electron conductive. 
     
     
         4 . The gas diffusion electrode as claimed in  claim 3  wherein the gas diffusion layer comprises a material selected from the group consisting of a metal or carbon mesh, woven or felt material, paper, or disc, a porous graphite film, a metal foam, a metal sinter, and combinations thereof. 
     
     
         5 . The gas diffusion electrode as claimed in  claim 4  wherein the gas diffusion layer further comprises a hydrophobic coating. 
     
     
         6 . The gas diffusion electrode as claimed in  claim 1  wherein the gas diffusion layer is electron non-conductive, the gas diffusion electrode further comprising an electron conductive layer. 
     
     
         7 . The gas diffusion electrode as claimed in  claim 6  wherein the gas diffusion layer comprises one of a hydrophobic porous polymer membrane, a hydrophobic polymer-woven material or paper, and combinations thereof. 
     
     
         8 . The gas diffusion electrode as claimed in  claim 7  wherein the gas diffusion layer comprises one of a porous ePTFE (expanded polytetrafluoroethylene) membrane and a porous PVDF (polyvinylidene difluoride) membrane. 
     
     
         9 . The gas diffusion electrode as claimed in  claim 6  wherein the electron conductive layer is a porous structure made of at least one of carbon and a metal. 
     
     
         10 . The gas diffusion electrode as claimed in  claim 1  wherein each opening of the set of one or more openings extends entirely through the gas diffusion layer in a direct fashion from one of the opposing sides to the other of the opposing sides. 
     
     
         11 . The gas diffusion electrode as claimed in  claim 10  wherein the set of one or more openings comprises a plurality of openings that are uniformly arranged. 
     
     
         12 . The gas diffusion electrode as claimed in  claim 10  wherein the set of one or more openings comprises a plurality of openings that are randomly arranged. 
     
     
         13 . The gas diffusion electrode as claimed in  claim 10  wherein the set of one or more openings comprises a plurality of regularly-shaped openings. 
     
     
         14 . The gas diffusion electrode as claimed in  claim 13  wherein the regularly-shaped openings are circular openings. 
     
     
         15 . The gas diffusion electrode as claimed in  claim 14  wherein the circular openings have a diameter that is larger than about 30 μm. 
     
     
         16 . The gas diffusion electrode as claimed in  claim 13  wherein the regularly-shaped openings are square openings. 
     
     
         17 . The gas diffusion electrode as claimed in  claim 13  wherein the regularly-shaped openings are rectangular slits. 
     
     
         18 . The gas diffusion electrode as claimed in  claim 17  wherein the rectangular slits are intersecting lines arranged in a rectangular grid pattern. 
     
     
         19 . The gas diffusion electrode as claimed in  claim 17  wherein the rectangular slits are non-intersecting lines arranged in a rectangular grid pattern. 
     
     
         20 . The gas diffusion electrode as claimed in  claim 10  wherein the set of one or more openings comprises a plurality of irregularly-shaped openings. 
     
     
         21 . The gas diffusion electrode as claimed in  claim 20  wherein the irregularly-shaped openings are slits. 
     
     
         22 . The gas diffusion electrode as claimed in  claim 10  wherein the set of one or more openings comprises a plurality of slits and wherein the slits have a length that exceeds about 1 millimeter. 
     
     
         23 . The gas diffusion electrode as claimed in  claim 1  wherein the gas diffusion layer consists of a single piece of material. 
     
     
         24 . The gas diffusion electrode as claimed in  claim 1  wherein the gas diffusion layer comprises a plurality of distinct pieces separated from one another by spaces and wherein the spaces form the one or more openings of the gas diffusion layer. 
     
     
         25 . The gas diffusion electrode as claimed in  claim 24  wherein the plurality of distinct pieces are arranged uniformly in a single plane in a rectangular grid pattern. 
     
     
         26 . The gas diffusion electrode as claimed in  claim 24  wherein the plurality of distinct pieces are arranged randomly in a single plane. 
     
     
         27 . A membrane electrode assembly suitable for use in a carbon dioxide electrolyzer, the membrane electrode assembly comprising:
 (a) an ion exchange membrane, the ion exchange membrane having an anode side and a cathode side;   (b) an anode coupled to the anode side of the ion exchange membrane; and   (c) the gas diffusion electrode of  claim 1  coupled to the cathode side of the ion exchange membrane.   
     
     
         28 . The membrane electrode assembly as claimed in  claim 27  wherein the gas diffusion layer is electron conductive, the membrane electrode assembly further comprising a water barrier layer positioned between the catalyst layer and the ion exchange membrane. 
     
     
         29 . The membrane electrode assembly as claimed in  claim 28  wherein the water barrier layer is a porous structure comprising one or more materials selected from the group of hydrophobic polymer particles, porous hydrophobic polymer particles, hydrophobic polymer fibers, and hydrophobic polymer pellets. 
     
     
         30 . The membrane electrode assembly as claimed in  claim 28  wherein the water barrier layer has a thickness in a range of about 200 nm to about 1 mm. 
     
     
         31 . The membrane electrode assembly as claimed in  claim 28  wherein the gas diffusion layer is electron conductive, the membrane electrode assembly further comprising a water capillary membrane positioned between the catalyst layer and the ion exchange membrane. 
     
     
         32 . The membrane electrode assembly as claimed in  claim 31  wherein the water capillary membrane is a porous and hydrophilic structure having a thickness in a range of about micrometers to about 1 millimeter. 
     
     
         33 . The membrane electrode assembly as claimed in  claim 31  further comprising a water barrier layer positioned between the water capillary membrane and the catalyst layer. 
     
     
         34 . The membrane electrode assembly as claimed in  claim 27  wherein the gas diffusion layer is electron non-conductive, the membrane electrode assembly further comprising an electron conductive layer positioned between the catalyst layer and the ion exchange membrane. 
     
     
         35 . The membrane electrode assembly as claimed in  claim 34  wherein the electron conductive layer is a porous structure comprising one or more materials selected from the group of carbon, copper, iron, stainless steel, silver, gold, nickel, aluminum, molybdenum, zinc, titanium, brass, and a metal alloy. 
     
     
         36 . The membrane electrode assembly as claimed in  claim 35  wherein the electron conductive layer has a thickness in a range from about 30 micrometers to about 2 millimeters. 
     
     
         37 . The membrane electrode assembly as claimed in  claim 34  further comprising a water capillary membrane positioned between the ion exchange membrane and the electron conductive layer. 
     
     
         38 . A carbon dioxide electrolyzer, the carbon dioxide electrolyzer comprising:
 (a) the membrane electrode assembly as claimed in  claim 27 ; and   (b) a voltage source, the voltage source operatively coupled to the membrane electrode assembly.