Catalyst for water splitting
Methods for producing a carbon-free, PGM-free support for PGM catalyst. The catalytic material comprises PGM metals disposed on a carbon-free support which is catalytic but free of PGM.
1. A method comprising:
preparing a platinum group metal (PGM)-free metal organic framework (MOF) material comprising MOF crystals;
forming a mixture of MOF crystals suspended in a polymer solution;
electrospinning the MOF crystals and polymer mixture, forming porous and interconnected nanofibers having MOF crystals uniformly dispersed;
subjecting the metal organic framework containing porous nanofiber to a first heat treatment forming carbon-based nanofibers;
depositing a platinum group metal on the carbon-based nanofibers forming a platinum group metal on nanofiber structure; and
annealing the platinum group metal on nanofiber structure, removing carbon and forming a PGM catalyst on a non-PGM metal oxide, carbon-free catalytic support.
2. The method of claim 1 , wherein the metal organic framework comprises a cobalt metal organic framework.
3. The method of claim 1 , wherein the metal organic framework comprises La co-doped with a transition metal selected from the group consisting of Co, Fe, Mn, Mo, Li, Nb, Ta, Zr, Y, and W.
4. The method of claim 1 , wherein the first heat treatment is a sequential thermolysis of the porous nanofiber.
5. The method of claim 4 , wherein the thermolysis comprises a thermal conversion temperature of between 300° C. and 900° C. for a thermal treatment period of 3-9 hours.
6. The method of claim 4 , wherein the thermolysis comprises a thermal conversion temperature of between 250° C. and 500° C. for a thermal treatment period of 1-6 hours.
7. The method of claim 4 , further comprising, following thermolysis, reducing the platinum group metal over the carbon based nanofibers.
8. The method of claim 7 , wherein reducing the platinum group metal comprises a solvothermal process and the use of a surfactant and a reducing agent selected from the group consisting of Benzyl alcohol, or salicylic acid or oleylamine.
9. The method of claim 1 , wherein depositing platinum group metal comprises depositing a metal selected from the group consisting of Ir, Ru, Pt, Rh, Pd, and combinations thereof.
10. The method of claim 1 , wherein the thermolysis is undergone in an environment selected from the group consisting of inert, reducing, and oxidizing.
11. The method of claim 1 , wherein the deposited platinum group metal has a mixture of amorphous and crystalline structure.
12. The method of claim 1 , further comprising oxidizing a portion of the platinum group metal after deposition.
13. A nanofiber catalyst comprising:
a transition metal oxide fibrous material having a plurality of pores within a series of transition metal oxide particles inter-connected and fused together in a nanofibrous network wherein the transition metal oxide particles comprise one or more of Co, Fe, Mn, Mo, Li, Nb, Ta, Zr, Y, and W; and
a plurality of platinum group metal particles disposed on the transition metal oxide particles wherein the plurality of platinum group particles comprise a metal selected from the group consisting of Ir, Ru, Pt, Rh, Pd, and combinations thereof, further wherein the plurality of platinum group metal particles have a mixture of amorphous and crystalline structures.
14. The nanofiber catalyst of claim 13 , wherein the transition metal oxide fibrous material is carbon-free.