Functionnalised copper electrochemical catalysts for conversion of co2 to small molecules

Abstract

The present invention belongs to the field of catalytic chemistry, and more specifically to catalysed reduction chemical reactions, preferably of CO 2 into small molecules. The present invention relates to a new catalyst compound comprising at least a copper (Cu) layer, wherein the copper layer is functionalized with at least one aryl group and its use thereof in a reduction chemical reaction, preferably in reduction of CO 2 into CO, ethylene and other small molecules such as gaseous hydrocarbons (methane, propane) or liquid molecules (ethanol, formic acid, propanol). The invention relates to the process of manufacture of said catalyst compound and to a process electrochemical conversion of CO 2 to small molecules and in particular ethylene.

1 . A process of manufacture of a catalyst compound comprising the steps of:
 a) depositing or coating copper on a porous gas diffusion layer, the porous gas diffusion layer being optionally pre-treated, preferably by electrodepositing copper, coating of copper particles and/or depositing of Cu particles using physical vapour deposition process such as metal evaporation or sputtering,   b) functionalization of the metal catalyst obtained in step a) by contacting with a diazonium salt of formula I:   
       
         
           
           
               
               
           
         
         wherein,
 X −  represents an anion,
 a is an integer from 1 to 3, 
 
 Ar A  represents an aryl group, substituted by at least one —R A  group, 
 —R A  represents at least one substituent chosen from a halo group, —R 1 , —NO 2 , —OR 1 , —NR 2 R 3  and a group of formula II: 
 
       
       
         
           
           
               
               
           
         
         in which, 
         —R 1  represents a C 1  to C 3  alkyl group, 
         —R 2  and R 3  independently represent H or a C 1  to C 3  alkyl group, 
         b is an integer from 0 to 3, 
         F B  is a functional group chosen from —N═N— and —NH—, 
         Ar B  represents an aryl group, optionally substituted by at least one —R B  group, 
         —R B  represents at least one substituent chosen from a halo group, —R 1 , —OR 1  and —NR 2 R 3 , 
            represent the point of attachment to Ar A . 
       
     
     
         2 . The process according to  claim 1 , wherein the copper is electrodeposited in a raspberry-like morphology. 
     
     
         3 . The process according to  claim 1 , further comprising a pre-treatment step a′) of electrodepositing Ag, Bi, Zn and/or Sn on the porous gas diffusion layer. 
     
     
         4 . The process according to  claim 1 , wherein X −  is chosen from BF 4   − , Cl −  and HSO 4   − . 
     
     
         5 . The process according to  claim 1 , wherein Ar A  and/or Ar B  are phenyl groups. 
     
     
         6 . The process according to  claim 1 , wherein the diazonium salt of formula I is chosen from the following salts: 
       
         
           
           
               
               
           
         
         
           
           
               
               
           
         
       
     
     
         7 . The process according to  claim 1 , further comprising a step c) of spray coating an ionomer of formula III: 
       
         
           
           
               
               
           
         
         wherein, 
         m and n are integers from 1 to 50,000. 
       
     
     
         8 . A catalyst compound obtained by the process according to  claim 1 . 
     
     
         9 . A catalyst compound comprising a porous gas diffusion layer, said porous gas diffusion layer being at least partially coated by copper atoms, wherein at least one copper atom is functionalised by a substituent of formula I′: 
       
         
           
           
               
               
           
         
       
       wherein Ar A , R A  and a are defined as in  claim 1  and   represents the point of attachment to copper. 
     
     
         10 . The compound according to  claim 9 , further comprising a Ag, Bi, Zn and/or Sn atom layer in between the porous gas diffusion layer and the copper layer. 
     
     
         11 . The compound according to  claim 9 , wherein the copper is in a raspberry-like morphology. 
     
     
         12 . The compound according to  claim 9 , wherein the porous gas diffusion layer is a commercial conducting carbon-based gas diffusion electrode or a porous polymer substrate such as PTFE, nylon or PVDF. 
     
     
         13 . Use of the compound according to  claim 9  as a catalyst, preferably to convert CO 2  into small molecules, preferably C 2 H 4 , C 2 H 5 OH, CO, formic acid, as well as small amount of H 2 . 
     
     
         14 . A process of conversion of CO 2  into small molecules comprising a step of contacting CO 2  with a catalyst compound according to  claim 9 . 
     
     
         15 . The process according to  claim 14 , wherein the conversion reaction of CO 2  is done under atmospheric pressure and at room temperature.