Non-platinum group metal electrocatalysts using metal organic framework materials and method of preparation
First Claim
1. A method of preparing a high surface area electrode catalyst free of platinum group metals (PGM) for use in a fuel cell, comprising:
- preparing a metal-organic framework (MOF) material consisting of a plurality of pores and also a non-PGM first transition metal catalytic center chemically bonded via a metal-nitrogen containing bond to an organic multidentate ligand in of the MOF material, the organic multidentate ligand and a first organic solvent contained within a portion of the plurality of pores, comprising;
dissolving a first transition metal salt in the first organic solvent to form a metal salt solution, wherein the non-PGM transition metal in the transition metal salt is selected from the group consisting of;
Co, Fe, Ni, Cr, Cu, Mn, Ta and W;
dissolving the organic multidentate ligand in the first organic solvent to form a ligand solution;
mixing a predetermined molar ratio of the metal salt solution and the ligand solution wherein the multidentate ligand is selected from the group consisting of imidazolate, pyrazolate, piperazine, tetrazolate, and combinations thereof into a reaction mixture; and
forming the MOF material by the step consisting of chemically bonding the non-PGM transition metal to the organic multidentate ligand to form the MOF material through a chemical reaction of forming a metal-nitrogen containing bond to the organic multidentate ligand and then separating the MOF material from the reaction mixture;
substituting at least a portion of the contained first organic solvent with a second chemical moiety to enhance formation of electrocatalytic active sites in the MOF material; and
thermally treating the MOF material for a predetermined period within an environment at a thermal conversion temperature to form the high surface area electrode catalyst having a plurality of uniformly distributed electrocatalytic active sites with catalytic centers arising from the non-PGM first transition metal chemically bonded in the thermally converted MOF material.
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Abstract
A method of preparing a nitrogen containing electrode catalyst by converting a high surface area metal-organic framework (MOF) material free of platinum group metals that includes a transition metal, an organic ligand, and an organic solvent via a high temperature thermal treatment to form catalytic active sites in the MOF. At least a portion of the contained organic solvent may be replaced with a nitrogen containing organic solvent or an organometallic compound or a transition metal salt to enhance catalytic performance. The electrode catalysts may be used in various electrochemical systems, including a proton exchange membrane fuel cell.
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Citations
15 Claims
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1. A method of preparing a high surface area electrode catalyst free of platinum group metals (PGM) for use in a fuel cell, comprising:
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preparing a metal-organic framework (MOF) material consisting of a plurality of pores and also a non-PGM first transition metal catalytic center chemically bonded via a metal-nitrogen containing bond to an organic multidentate ligand in of the MOF material, the organic multidentate ligand and a first organic solvent contained within a portion of the plurality of pores, comprising; dissolving a first transition metal salt in the first organic solvent to form a metal salt solution, wherein the non-PGM transition metal in the transition metal salt is selected from the group consisting of;
Co, Fe, Ni, Cr, Cu, Mn, Ta and W;dissolving the organic multidentate ligand in the first organic solvent to form a ligand solution; mixing a predetermined molar ratio of the metal salt solution and the ligand solution wherein the multidentate ligand is selected from the group consisting of imidazolate, pyrazolate, piperazine, tetrazolate, and combinations thereof into a reaction mixture; and forming the MOF material by the step consisting of chemically bonding the non-PGM transition metal to the organic multidentate ligand to form the MOF material through a chemical reaction of forming a metal-nitrogen containing bond to the organic multidentate ligand and then separating the MOF material from the reaction mixture; substituting at least a portion of the contained first organic solvent with a second chemical moiety to enhance formation of electrocatalytic active sites in the MOF material; and thermally treating the MOF material for a predetermined period within an environment at a thermal conversion temperature to form the high surface area electrode catalyst having a plurality of uniformly distributed electrocatalytic active sites with catalytic centers arising from the non-PGM first transition metal chemically bonded in the thermally converted MOF material. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A method of preparing a nitrogen containing electrode catalyst free of precious group metals (PGM), comprising:
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synthesizing a metal-organic framework (MOP) electrode catalyst precursor, the MOF electrode catalyst precursor consisting of a plurality of pores, a first non-PGM transition metal chemically bonded with a metal-nitrogen bond to the MOF electrode catalyst precursor, with a multidentate ligand containing nitrogen, and a first organic solvent disposed within the plurality of pores in the MOF electrode catalyst precursor; wherein the multidentate ligand is selected from the group consisting of imidazolate, pyrazolate, piperazine, tetrazolate, and combinations thereof; substituting at least a portion of the first organic solvent disposed within the plurality of pores in the MOF electrode catalyst precursor with one of a nitrogen-containing organic solvent and a second non-PGM transition metal; and thermally activating the MOF electrode catalyst precursor by an elevated temperature treatment to form a plurality of uniformly distributed electrocatalytic active sites. - View Dependent Claims (12, 13, 14, 15)
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Specification