Porous transport layer for carbon dioxide electrolyzers

Abstract

Carbon oxide electrolyzers may be characterized by: (a) a membrane electrode assembly (MEA) comprising a cathode layer, an anode layer, and one or more polymeric electrolyte layers between and in contact with the cathode layer and the anode layer; (b) a porous transport layer (PTL) proximate the anode layer, and (c) optionally, a microporous layer (MPL) disposed between the MEA and the PTL.

What is claimed is: 
     
         1 . A carbon oxide electrolyzer comprising:
 a membrane electrode assembly (MEA) comprising a cathode layer, an anode layer, and one or more polymeric electrolyte layers between and in contact with the cathode layer and the anode layer; and   a porous transport layer (PTL) in contact with the anode layer and having a porous structure with an average pore size of about 10 to 50 μm, and an average porosity of about 20 to 50%.   
     
     
         2 . The carbon oxide electrolyzer of  claim 1 , wherein the carbon oxide electrolyzer is configured to operate at a temperature of about 0 to 80° C., electrolyze anode water having a metal ion concentration of at least about 0.5 mM, and operate at an anode current density of about 1000 mA/cm 2  or lower. 
     
     
         3 . The carbon oxide electrolyzer of  claim 2 , wherein the carbon oxide electrolyzer is configured to electrolyze carbon dioxide and produce carbon monoxide. 
     
     
         4 . The carbon oxide electrolyzer of  claim 2 , wherein the carbon oxide electrolyzer is configured to electrolyze carbon dioxide and produce a hydrocarbon, an alcohol, a carboxylic acid, an aldehyde, or any combination thereof. 
     
     
         5 . The carbon oxide electrolyzer of  claim 1 , wherein the carbon oxide electrolyzer is configured to electrolyze anode water at a rate of about 1 L/hr or greater. 
     
     
         6 . The carbon oxide electrolyzer of  claim 1 , further comprising an anode flow field in contact with the PTL, on a side of the PTL opposite from the anode layer. 
     
     
         7 . The carbon oxide electrolyzer of  claim 1 , wherein the PTL comprises titanium having a concentration of at least about 50% by weight. 
     
     
         8 . The carbon oxide electrolyzer of  claim 1 , wherein the PTL comprises niobium having a concentration of at least about 50% by weight. 
     
     
         9 . The carbon oxide electrolyzer of  claim 1 , wherein the PTL comprises a base material and coating comprising platinum, gold, titanium nitride, or any combination thereof. 
     
     
         10 . The carbon oxide electrolyzer of  claim 1 , wherein the PTL has a thickness about 0.2-0.5 mm. 
     
     
         11 . The carbon oxide electrolyzer of  claim 1 , wherein the PTL has a graded structure in which the average pore size and/or the average porosity varies when moving in a direction away from the anode layer of the MEA. 
     
     
         12 . The carbon oxide electrolyzer of  claim 1 , wherein the PTL has a graded hydrophobicity in which the PTL's hydrophobicity increases when moving in a direction away from the anode layer of the MEA. 
     
     
         13 . The carbon oxide electrolyzer of  claim 1 , wherein the PTL has a mesh structure, and wherein the carbon oxide electrolyzer does not include an anode flow field. 
     
     
         14 . The carbon oxide electrolyzer of  claim 1 , wherein the PTL has a compressibility, through its thickness, of about 0.7 to 1.3 μm at 1 MPa, or about 1.2 to 1.8 μm at 2 MPa, or about 1.7 to 2.3 μm at 4 MPa. 
     
     
         15 . The carbon oxide electrolyzer of  claim 1 , wherein the PTL has a flexural modulus of about 10-170 GPa. 
     
     
         16 . The carbon oxide electrolyzer of  claim 1 , wherein the PTL has a yield strength of about 800 to 900 MPa. 
     
     
         17 . The carbon oxide electrolyzer of  claim 1 , wherein the PTL comprises of sintered particles having non-spherical shapes. 
     
     
         18 . The carbon oxide electrolyzer of  claim 1 , wherein the PTL has a roughness of about 11 to 16 μm where the PTL contacts the anode layer. 
     
     
         19 . The carbon oxide electrolyzer of  claim 1 , wherein the PTL comprises a composite structure. 
     
     
         20 . A carbon oxide electrolyzer comprising:
 a membrane electrode assembly (MEA) comprising a cathode layer, an anode layer, and one or more polymeric electrolyte layers between and in contact with the cathode layer and the anode layer;   a microporous layer (MPL) in contact with the anode layer; and   a porous transport layer (PTL) in contact with the MPL on a side of the MPL opposite the anode layer, wherein the PTO has a porous structure with an average pore size of about 10 to 50 μm, and an average porosity of about 20 to 50%.   
     
     
         21 . The carbon oxide electrolyzer of  claim 20 , wherein the MPL has a roughness of about 11 to 16 μm where the MPL contacts the anode layer. 
     
     
         22 . The carbon oxide electrolyzer of  claim 20 , wherein the carbon oxide electrolyzer is configured to electrolyze anode water flow rate of about 1 L/hr or greater. 
     
     
         23 . The carbon oxide electrolyzer of  claim 20 , further comprising an anode flow field in contact with the PTL, on a side of the PTL opposite from the MPL. 
     
     
         24 . A method of operating a carbon oxide electrolyzer, the method comprising:
 providing anode water to an anode portion of a carbon oxide electrolyzer comprising: (a) a membrane electrode assembly (MEA) comprising a cathode layer, an anode layer, and one or more polymeric electrolyte layers between and in contact with the cathode layer and the anode layer, and (b) a porous transport layer (PTL) proximate to the anode layer and having a porous structure with an average pore size of about 10 to 50 μm, and an average porosity of about 20 to 50%;   electrochemically oxidizing the anode water at the anode layer to produce oxygen; and   electrochemically reducing the carbon oxide at the cathode layer to produce a carbon-containing product.   
     
     
         25 . The method of  claim 24 , wherein electrochemically oxidizing the water at the anode layer is performed at a temperature of about 0 to 80° C. and an anode current density of about 1000 mA/cm 2  or lower. 
     
     
         26 . The method of  claim 24 , wherein the anode water has a metal ion concentration of at least about 0.5 mM. 
     
     
         27 . The method of  claim 24 , wherein electrochemically reducing the carbon oxide at the cathode layer comprises electrolyzing carbon dioxide to produce carbon monoxide. 
     
     
         28 . The method of  claim 24 , wherein electrochemically reducing the carbon oxide at the cathode layer comprises electrolyzing carbon dioxide to produce a hydrocarbon, an alcohol, a carboxylic acid, an aldehyde, or any combination thereof. 
     
     
         29 . The method of  claim 25 , wherein electrochemically oxidizing the anode water at the anode layer comprises flowing the anode water to the anode layer at a flow rate of about 1 L/hr or greater. 
     
     
         30 . The method of  claim 24 , wherein the carbon oxide electrolyzer further comprises an anode flow field in contact with the PTL, on a side of the PTL opposite from the anode layer. 
     
     
         31 . The method of  claim 24 , wherein the PTL has a graded structure in which the average pore size and/or the average porosity varies when moving in a direction away from the anode layer of the MEA. 
     
     
         32 . The method of  claim 24 , wherein the PTL has a graded hydrophobicity in which the PTL's hydrophobicity increases when moving in a direction away from the anode layer of the MEA. 
     
     
         33 . The method of  claim 24 , wherein the PTL has a compressibility, through its thickness, of about 0.7 to 1.3 μm at 1 MPa, or about 1.2 to 1.8 μm at 2 MPa, or about 1.7 to 2.3 μm at 4 MPa. 
     
     
         34 . The method of  claim 24 , wherein the PTL has a flexural modulus of about 10-170 GPa. 
     
     
         35 . The method of  claim 24 , wherein the PTL has a yield strength of about 800 to 1300 MPa. 
     
     
         36 . The method of  claim 24 , wherein the carbon oxide electrolyzer further comprises a microporous layer (MPL) between the anode layer and the PTL, and in contact with the anode layer. 
     
     
         37 . The method of  claim 36 , wherein the MPL has a roughness of about 11 to 16 μm where the MPL contacts the anode layer. 
     
     
         38 . The method of  claim 36 , wherein the carbon oxide electrolyzer further comprises an anode flow field in contact with the PTL, on a side of the PTL opposite from the MPL.