Metal nitride catalysts for promoting a hydrogen evolution reaction

Abstract

The present invention provides metal nitrides and methods of making and using same, including using such metal nitrides as catalysts for hydrogen evolution reactions.

1 . A catalyst for promoting a hydrogen evolution reaction, the catalyst comprising a metal nitride having a formula:
   M′ x M″ y N z  
   wherein M′ is selected from the group consisting of Ag, Al, Ca, Co, Cr, Cu, Fe, Ga, In, Li, Mg, Mn, Na, Ni, Sc, Ti, V, Y, Zn, and mixtures thereof;   wherein M″ is selected from the group consisting of Hf, Mo, Nb, Re, Ru, Ta, W, Zr, and mixtures thereof;   wherein x is a number from 0 to 1;   wherein y is a number from 1 to 2;   wherein z is a number greater than 1.8 and less than 2.2; and   wherein the metal nitride comprises a hexagonal lattice with a four-layered stacking sequence that comprises two formula units of mixed close packed structure with alternating layers of M′ metals in trigonal prismatic coordination and; M′, or M′ and M″ metals in octahedral coordination.   
     
     
         2 . The catalyst of  claim 1 , wherein M′ is selected from the group consisting Ag, Ca, Co, Cr, Fe, Mg, Mn, Ni, Zn, and mixtures thereof. 
     
     
         3 . (canceled) 
     
     
         4 . The catalyst of  claim 2 , wherein M″ is Mo. 
     
     
         5 . The catalyst of  claim 1 , wherein the metal nitride comprises lattice parameters of about 2.85×2.85×11.0 Å. 
     
     
         6 . The catalyst of  claim 2 , wherein x is a number greater than 0.4 and less than 0.8 
     
     
         7 . (canceled) 
     
     
         8 . The catalyst of  claim 6 , wherein y is a number greater than 1.2 and less than 1.6. 
     
     
         9 . (canceled) 
     
     
         10 . The catalyst of  claim 8 , wherein z is a number greater than 1.9 and less than 2.1. 
     
     
         11 . (canceled) 
     
     
         12 . The catalyst of  claim 1 , wherein the metal nitride occupies a P6 3 /mmc space group. 
     
     
         13 . The catalyst of  claim 1 , wherein M′ is Co, M″ is Mo, x is about 0.6, y is about 1.4, and z is about 2. 
     
     
         14 . The catalyst of  claim 1 , wherein the catalyst promotes the hydrogen evolution reaction with a low onset potential between about −1 mV and about −200 mV under acidic conditions. 
     
     
         15 . The catalyst of  claim 14 , wherein the onset potential is between about −75 mV and about −150 mV. 
     
     
         16 . A method of producing hydrogen, the method comprising
 (a) providing a one chamber electrochemical cell comprising:
 an anode; 
 supporting electrolytes and a reagent solution; 
 a cathode comprising a hydrogen evolution reaction catalyst, wherein the catalyst comprises a metal nitride having a formula:
   M′ x M″ y N z  
 
 wherein M′ is selected from the group consisting of Ag, Al, Ca, Co, Cr, Cu, Fe, Ga, In, Li, Mg, Mn, Na, Ni, Sc, Ti, V, Y, Zn, and mixtures thereof; 
 wherein M″ is selected from the group consisting of Hf, Mo, Nb, Re, Ru, Ta, W, Zr, and mixtures thereof; 
 wherein x is a number from 0 to 1; 
 wherein y is a number from 1 to 2; 
 wherein z is a number greater than 1.8 and less than 2.2; and 
 wherein the metal nitride comprises a hexagonal lattice with a four-layered stacking sequence that comprises two formula units of mixed close packed structure with alternating layers of M″ metals in trigonal prismatic coordination; 
 
 and M′, or M′ and M″ metals in octahedral coordination; and 
   (b) applying current to the electrochemical cell, whereby hydrogen is produced at the cathode.   
     
     
         17 . The method of  claim 16 , wherein the reagent solution has a pH of about 0 to 3. 
     
     
         18 . The method of  claim 16 , wherein M′ is selected from the group consisting Ag, Ca, Co, Cr, Fe, Mg, Mn, Ni, Zn, and mixtures thereof. 
     
     
         19 . (canceled) 
     
     
         20 . The method of  claim 18 , wherein M″ is Mo. 
     
     
         21 . The method of  claim 16 , wherein the metal nitride comprises lattice parameters of about 2.85×2.85×11.0 Å. 
     
     
         22 . The method of, wherein x is a number greater than 0.4 and less than 0.8, y is a number greater than 1.2 and less than 1.6, and z is a number greater than 1.9 and less than 2.1. 
     
     
         23 - 27 . (canceled) 
     
     
         28 . The method of  claim 16 , wherein the metal nitride occupies a P6 3 /mmc space group. 
     
     
         29 . The method of  claim 16 , wherein M′ is Co, M″ is Mo, x is about 0.6, y is about 1.4, and z is about 2. 
     
     
         30 . The method of  claim 16 , wherein the catalyst promotes the hydrogen evolution reaction with a low onset potential between about −1 mV and about −200 mV under acidic conditions. 
     
     
         31 - 32 . (canceled)