Stable Catalyst Ink Formulations, Methods of Using Such Inks in Fiber Formation, and Articles Comprising Such Fibers

Abstract

The present invention relates to stable catalyst ink formulations comprising am electrospinning polymer selected from halogen-comprising polymers. The present invention further relates to electrospinning of such ink formulation, to the so-obtained electrospun fibrous mat as well as to articles comprising such electrospun fibrous mat.

1 . Ink formulation comprising
 (i) metal supported on a carrier,   (ii) an ionomer,   (iii) an electrospinning polymer selected from the group of halogen-comprising polymers, and   (iv) a solvent.   
     
     
         2 . Ink formulation according to  claim 1 , wherein the metal is selected from the group consisting of Sc, Y, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Fe, Ru, Os, Co, Rh, Ir, Ni, Pd, Pt, Cu, Ag, Au, Zn, Cd, Hg, lanthanides, actinides and any blend thereof. 
     
     
         3 . Ink formulation according to  claim 1 , wherein the carrier is selected from the group consisting of carbon, silica, metal oxides, metal halides and any blend thereof. 
     
     
         4 . Ink formulation according to  claim 1 , wherein the ionomer comprises electrically neutral repeating units and ionized or ionizable repeating units. 
     
     
         5 . Ink formulation according to  claim 1 , wherein the halogen-comprising polymer comprises fluorine, chlorine or both, fluorine and chlorine. 
     
     
         6 . Ink formulation according to  claim 5 , wherein the halogen-comprising polymer comprises an alkanediyl monomer unit of general formula (III)
   *—[C 2 H 4-p-q-r Y 1   p Y 2   q Y 3   r ]—*  (III)
   wherein   p is selected from the group consisting of 1, 2, 3 and 4;   q is selected from the group consisting of 0, 1, 2 and 3;   r is selected from the group consisting of 0, 1, 2 and 3;   Y 1  is fluorine;   Y 2  is chlorine; and   Y 3  is, at each occurrence independently of the other, selected from the group consisting of alkyl having from 1 to 20 carbon atoms, halogenated alkyl having from 1 to 20 carbons atoms, alkoxy having from 1 to 20 carbon atoms and halogenated alkoxy having from 1 to 20 carbon atoms, and the respective alkyl and alkoxy wherein one or more carbon atoms are replaced by a heteroatom, which is selected from the group consisting of —O—, —S—, —Se—, —N(R 18 )—, ═N—, —P(R 18 )—, —Si(R 18 )(R 19 )—, and —Ge(R 18 )(R 19 )— with R 18  and R 19  being independently of one another selected from alkyl or halogenated alkyl having from 1 to 20 carbon atoms and cycloalkyl or halogenated cycloalkyl having from 3 to 20 carbon atoms,   with the provision that p+q+r≤4.   
     
     
         7 . Ink formulation according to  claim 1 , wherein the ink formulation comprises at least 1 wt % and at most 30 wt % of combined amounts of metal with carrier, ionomer and electrospinning polymer, with wt % relative to the total weight of the ink formulation. 
     
     
         8 . Ink formulation according to  claim 1 , wherein the ink formulation comprises the metal with carrier, the ionomer and the electrospinning polymer in a ratio of A:B:C with A being at least parts and at most 80 parts, B being at least 1 part and at most 40 parts and C being at most 60 parts, with the sum of A, B and C being 100 parts, with parts being given as weight parts. 
     
     
         9 . Ink formulation according to  claim 1 , wherein the solvent is selected from the group consisting of water and organic solvents. 
     
     
         10 . Ink formulation according to  claim 1 , wherein the solvent is selected from the group consisting of water, ethers of general formula R 13 —O—R 14 , alcohols of general formula R 15 —OH, ketones of general formula R 16 —C(═O)—R 17 , amides of general formula (R 16 ) 2 N—C(═O)—R 17  and any blends thereof, wherein R 13 , R 14 , R 15  and R 16  are independently of each other selected from alkyl having from 1 to 10 carbon atoms and fluorinated alkyl having from 1 to 10 carbon atoms, and R 17  is selected from the group consisting of H, alkyl having from 1 to 10 carbon atoms and fluorinated alkyl having from 1 to 10 carbon atoms, or R 13  and R 14  may together be selected from alkanediyl having from 4 to 6 carbon atoms and fluorinated alkanediyl having from 3 to 6 carbon atoms, or R 16  and R 17  may together be selected from alkanediyl having from 4 to 6 carbon atoms and from fluorinated alkanediyl having from 4 to 6 carbon atoms. 
     
     
         11 . Process for the production of an electrospun fibrous mat, said process comprising the steps of
 (a) providing to an electrospinning apparatus the ink formulation of  claim 1 , and   (b) subsequently electrospinning the ink formulation to obtain an electrospun fibrous mat.   
     
     
         12 . (canceled) 
     
     
         13 . Process according to  claim 11 , wherein step (b) is performed by nozzle-free electrospinning. 
     
     
         14 . Process according to  claim 11 , wherein the electrospinning apparatus comprises two electrodes, the distance between which is at least 0.01 m and at most 2 m. 
     
     
         15 . Electrospun fibrous mat comprising
 (i) metal supported on a carrier,   (ii) an ionomer, and   (iii) an electrospinning polymer selected from the group of halogen-comprising polymers.   
     
     
         16 . Electrospun fibrous mat having been prepared by the process according to  claim 11 . 
     
     
         17 . Membrane electrode assembly comprising the electrospun fibrous mat  claim 15 . 
     
     
         18 . Fuel cell comprising the membrane electrode assembly of  claim 17 . 
     
     
         19 . The electrospun fibrous mat according to  claim 15 , which is in a single layer.