Compositions and processes for optimizing oxygen reduction and oxygen evolution reactions

Abstract

Compositions and processes for optimizing oxygen reduction and oxygen evolution reactions are provided. Oxygen reduction and oxygen evolution catalysts include oxide compositions having a general formula a formula A2-xMOy, where x is electrochemically tuned to find optimal A content that delivers the best catalytic performance in a chemical system. The process provides the ability to find the optimal catalytic performance by tuning A and hence, the binding strength of O.

What is claimed is: 
     
         1 . An oxygen reduction reaction (ORR) and/or oxygen evolution reaction (OER) catalyst comprising a formula A 2-x MO y ;
 wherein A is Li,   wherein y is 2 to 3,   wherein M comprises a precious metal,   wherein the ORR and/or OER catalyst has an oxygen vacancy formation energy or oxygen binding energy of about −1 to about 1 eV/atom obtained by electrochemically tuning x in a range of 0 to 2.   
     
     
         2 . The ORR and/or OER catalyst of  claim 1  wherein M comprises at least one of Rh, Jr, Ru, Pd, Au, Ag, Os and mixtures thereof. 
     
     
         3 . The ORR and/or OER catalyst of  claim 1  wherein M is at least one of Rh, Pd, and mixtures thereof. 
     
     
         4 . The ORR and/or OER catalyst of  claim 1  wherein M is at least one Ru, Jr, and mixtures thereof. 
     
     
         5 . The ORR and/or OER catalyst of  claim 1  wherein M is selected from the group consisting of Pt/Fe, Rh/Ni, and Pd/Mn. 
     
     
         6 . The ORR and/or OER catalyst of  claim 1  wherein the ORR and/or OER catalyst is a layered crystal structure capable of insertion and desorption of lithium ions. 
     
     
         7 . The ORR and/or OER catalyst of  claim 1  wherein the ORR and/or OER catalyst is provided in a nanoparticle structure. 
     
     
         8 . The ORR and/or OER catalyst of  claim 1  wherein the ORR and/or OER catalyst is provided in a nanosheet structure. 
     
     
         9 . An oxygen reduction reaction (ORR) and/or oxygen evolution reaction (OER) catalyst comprising a formula A 2-x MO y ;
 wherein A is Li,   wherein y is 3,   wherein M comprises is a precious metal selected from at least one of Rh, Jr, Ru, Pd, Au, Ag, Os and mixtures thereof,   wherein the ORR and/or OER catalyst has an oxygen vacancy formation energy or oxygen binding energy of about −1 to about 1 eV/atom obtained by electrochemically tuning x in a range of 0 to 2, and the ORR and/or OER catalyst is provided in an at least one of a nanoparticle structure and a nanosheet structure.   
     
     
         10 . The ORR and/or OER catalyst of  claim 9  wherein M is at least one of Rh, Pd, and mixtures thereof. 
     
     
         11 . The ORR and/or OER catalyst of  claim 9  wherein M is at least one Ru, Jr, and mixtures thereof. 
     
     
         12 . The ORR and/or OER catalyst of  claim 9  wherein M is selected from the group consisting of Pt/Fe, Rh/Ni, and Pd/Mn. 
     
     
         13 . The ORR and/or OER catalyst of  claim 9  wherein the ORR and/or OER catalyst is a layered crystal structure capable of insertion and desorption of lithium ions. 
     
     
         14 . A process for optimizing oxygen reduction or oxygen evolution catalytic activity, the process comprising:
 providing an oxygen reduction (ORR) and/or oxygen evolution reaction (OER) catalyst of a formula A 2-x MO y ;
 wherein A is Li, 
 wherein x is 0 to 2, 
 wherein y is 2 to 3, 
 wherein M comprises a precious metal selected from at least one of Rh, Jr, Ru, Pd, Au, Ag, Os and mixtures thereof; and 
 electrochemically tuning an initial value of x to improve catalytic activity of oxygen reduction or oxygen evolution reactions. 
   
     
     
         15 . The process of  claim 14  wherein M is at least one of Rh, Pd, and mixtures thereof. 
     
     
         16 . The process of  claim 14  wherein M is at least one of Ru, Jr, and mixtures thereof. 
     
     
         17 . The process of  claim 14  wherein M is selected from the group consisting of Rh/Ni and Pd/Mn. 
     
     
         18 . The process of  claim 14  wherein the electrochemically tuning of an initial value of x includes applying a bias to the ORR and/or OER catalyst. 
     
     
         19 . The process of  claim 14  wherein the process includes electrochemically tuning an amount of A by applying a current to the ORR and/or OER catalyst to provide an oxygen binding strength for absorption or desorption of oxygen. 
     
     
         20 . The process of  claim 14  wherein the ORR and/or OER catalyst is a layered crystal structure capable of insertion and desorption of lithium ions.