Niobium (nb)-based atomically distributed electrocatalysts for water electrolysis

Abstract

The present disclosure relates to a catalyst composition with a plurality of niobium atoms that are atomically dispersed and coordinated to heteroatoms within a doped carbon support. The method for synthesizing the catalyst composition involves dissolving a carbon source in a first solution, dissolving a niobium source and a dopant source in a second solution, mixing the solutions to form a mixture, drying the mixture to form a precursor material, and pyrolyzing the precursor material. The catalyst composition exhibits exceptional performance in catalyzing electrochemical reactions, particularly hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), in both acidic and alkaline conditions. The catalyst composition demonstrates low overpotentials and high current densities at industrially relevant current densities with superior stability, enabling its application in scalable, cost-effective, and energy-efficient water electrolyzers.

We claim: 
     
         1 . A catalyst composition, comprising:
 a plurality of niobium atoms that are atomically dispersed; and   a doped carbon support;   wherein each niobium atom of the plurality of niobium atoms is coordinated to heteroatoms within the doped carbon support.   
     
     
         2 . The catalyst composition of  claim 1 , wherein the heteroatoms within the doped carbon support comprise at least one heteroatom selected from the group consisting of nitrogen, sulfur, boron, oxygen, and phosphorus. 
     
     
         3 . The catalyst composition of  claim 1 , wherein the plurality of niobium atoms are atomically dispersed such that each niobium atom is isolated from other niobium atoms or is grouped with no more than two other niobium atoms. 
     
     
         4 . The catalyst composition of  claim 1 , wherein the plurality of niobium atoms are atomically dispersed such that any cluster of niobium atoms of the plurality of niobium atoms has a maximum dimension of less than 0.5 nanometers. 
     
     
         5 . The catalyst composition of  claim 1 , wherein the doped carbon support has a hierarchical porous structure. 
     
     
         6 . The catalyst composition of  claim 1 , wherein the doped carbon support is graphitic. 
     
     
         7 . The catalyst composition of  claim 1 , further comprising a plurality of atoms of a second metal that are atomically dispersed and coordinated to heteroatoms within the doped carbon support. 
     
     
         8 . The catalyst composition of  claim 7 , wherein the second metal is molybdenum. 
     
     
         9 . A method for synthesizing a catalyst composition, the method comprising:
 dissolving a carbon source in a first solution;   dissolving a niobium source and a dopant source in a second solution;   mixing the first solution with the second solution to form a mixture;   drying the mixture to form a precursor material; and   pyrolyzing the precursor material to form the catalyst composition;   wherein the catalyst composition comprises niobium atoms that are atomically dispersed and coordinated to heteroatoms within a doped carbon support.   
     
     
         10 . The method of  claim 9 , wherein the carbon source is a carbohydrate, the niobium source is niobium (V) chloride, and the dopant source is hydroxylamine hydrochloride. 
     
     
         11 . The method of  claim 9 , wherein the doped carbon support is graphitic. 
     
     
         12 . The method of  claim 9 , wherein pyrolyzing is conducted beginning at room temperature and ending at a temperature of at least 600° C. under an argon atmosphere. 
     
     
         13 . The method of  claim 12 , wherein pyrolyzing is conducted with a temperature ramp rate of approximately 5° C./min. 
     
     
         14 . The method of  claim 9 , wherein drying is conducted at 70° C. or less, for at least 12 hours. 
     
     
         15 . A method of catalyzing an electrochemical reaction, comprising:
 loading at least one electrode of an electrochemical cell with a catalyst composition comprising niobium atoms that are atomically dispersed and coordinated to heteroatoms within a doped carbon support; and   applying a potential across the electrochemical cell;   wherein the catalyst composition catalyzes at least one of a hydrogen evolution reaction (HER) and an oxygen evolution reaction (OER).   
     
     
         16 . The method of  claim 15 , wherein the electrochemical reaction occurs in both alkaline and acidic conditions. 
     
     
         17 . The method of  claim 15 , wherein an overpotential required to achieve a current density of 100 mA/cm 2  is less than 175 mV for HER and less than 325 mV for OER. 
     
     
         18 . The method of  claim 15 , wherein the catalyst composition exhibits stability under continuous operation at a current density of 100 mA/cm 2  for at least 35 hours, with a performance degradation of less than 2%. 
     
     
         19 . The method of  claim 15 , wherein the catalyst composition is bifunctional and is loaded at a cathode and an anode within the electrochemical cell. 
     
     
         20 . The method of  claim 15 , wherein the catalyst composition catalyzes both HER and OER.