Polymer-supported electrodes containing multi-atomic clusters and methods of making and using same
Atomic mixed metal electrodes, including electrodes containing a conductive polymer-mixed metal complex, as well as methods of making and using the same, are disclosed. In some embodiments, the atomic mixed metal electrode can be described as a conductive polymer-coated electrode having mixed metal clusters complexed to the conductive polymer at levels of between 2 and 10 metal atoms. A method for preparing the conductive polymer-mixed metal complexes is disclosed that can deposit metal atoms one at a time into a complex with the conductive polymer, allowing for highly tailored atomic clusters. A method of oxidizing alcohols, and the application to devices such as fuel cells are also disclosed.
1. A method of making an atomic metal with a desired catalytic activity comprising:
coating a substrate with a conductive polymer film;
preconditioning the conductive film by oxidizing the conductive polymer film;
forming from one metal a conductive polymer-metal-X n − complex;
reducing the conductive polymer-metal-X n − complex to form an atomic metal-conductive polymer complex; and
sequentially repeating the steps of forming and reducing (N−1) number of times to create a conductive polymer-(metal) N complex;
wherein N is 2 to 10;
wherein at least two different metals are used; and
wherein the order of selection of the single metal-X n − complex used in each step of forming and reducing is determined based upon a desired catalytic activity of the atomic metal.
2. The method of claim 1 wherein:
the substrate comprises an electrode;
the metals are noble metals;
the step of forming the conductive polymer-metal-X n − complex comprises forming a conductive polymer-noble metal-X n − complex;
the step of reducing the conductive polymer-metal-X n − complex to form an atomic metal-conductive polymer complex comprises reducing the conductive polymer-noble metal-X 4 − complex to form an atomic noble metal-conductive polymer complex; and
repeating the steps of forming and reducing (N−1) number of times creates a conductive polymer-noble metal N complex.
3. The method of claim 2 , wherein the coating step comprises treating at least a portion of the electrode with a conductive polymer solution at positive potential.
4. The method of claim 3 , wherein the conductive polymer is selected from the group consisting of polyaniline (PANI), polypyrrole, and polypyridine.
5. The method of claim 3 , wherein the conductive polymer is PANI.
6. The method of claim 2 , wherein the preconditioning step comprises cycling a potential from −0.2V to +0.7V, then holding the potential at least about +0.8V for at least 30 minutes.
7. The method of claim 2 , wherein the forming step comprises:
holding the conductive polymer at about 0.7 V; and
exposing the conductive polymer to noble metal-X 4 − in an acidic medium.
8. The method of claim 2 , wherein the reducing step comprises sweeping the potential to −0.2V.
9. The method of claim 2 , wherein the noble metals are gold and palladium.
10. The method of claim 1 , wherein N is at least 3.
11. The method of claim 2 , wherein the forming step comprises:
holding the conductive polymer at about 0.7 V; and
exposing the conductive polymer to noble metal-X n − in a buffer having a pH of approximately 7.
12. The method of claim 2 , wherein the forming step comprises:
holding the conductive polymer at about 0.7 V; and
exposing the conductive polymer to noble metal-X n − in a phosphate buffer having a pH of approximately 7.
13. The method of claim 1 , wherein the desired catalytic activity of the atomic metal is selected from the group consisting of a desired HOMO-LUMO gap energy, a desired reaction rate, a desired selectivity, and a desired lifetime.
14. The method of claim 13 , wherein the substrate comprises an electrode and the method forms an atomic metal electrode.
15. The method of claim 2 , wherein the noble metals are gold and palladium;
wherein N is 3; and
wherein palladium and gold are used in repeating the steps of forming and reducing to obtain a terminal arrangement of Pd—Au in the atomic noble metal electrode.
16. A method of making an atomic metal with a desired catalytic activity comprising:
coating a portion of a substrate with a conductive polymer film;
preconditioning a portion of the conductive film by oxidizing the conductive polymer film;
forming from one metal a conductive polymer-metal-X n − complex by:
holding the conductive polymer film at a positive potential; and
exposing the conductive polymer film to metal-X n − in a medium;
reducing the conductive polymer-metal-X n − complex to form an atomic metal-conductive polymer complex; and
sequentially repeating the steps of forming and reducing (N−1) number of times to create a conductive polymer-(metal) N complex;
wherein N is an integer greater than 1;
wherein at least two different metals are used; and
wherein the sequential order of forming and reducing the conductive polymer-one metal-X n − complex is determined based upon a desired catalytic activity of the atomic metal.
17. A method of making an atomic metal with a desired catalytic activity comprising:
coating at least a portion of a substrate with a polymer film;
preconditioning at least a portion of the polymer film by oxidizing a portion of the polymer film;
forming from one metal a polymer-metal-X n − complex;
reducing the polymer-metal-X n − complex to form an atomic metal-polymer complex; and
sequentially repeating the steps of forming and reducing (N−1) number of times to create a polymer-metal N complex;
wherein N is an integer greater than 1;
wherein (M) number of different metal-X n − complexes are used;
wherein (M) is an integer from 2 to (N−1);
wherein the number of permutations of the atomic metal formed of (M) number of different metal-X n − complexes deposited (N) times is given by:
P
(
N
,
M
)
=
N
!
(
N
-
M
)
!
(
1
)
wherein the order of selection of the metal-X n − complex used in each step of forming and reducing is determined based upon a desired catalytic activity of the atomic metal.
18. The method of claim 17 , wherein the desired catalytic activity of the atomic metal comprises selecting a desired HOMO-LUMO gap energy from among the P(N,M) choices.
19. The method of claim 17 , wherein the desired catalytic activity of the atomic metal comprises selecting a desired reaction rate from among the P(N,M) choices.
20. The method of claim 17 , wherein the desired catalytic activity of the atomic metal comprises selecting a desired selectivity from among the P(N,M) choices.
21. The method of claim 17 , wherein the desired catalytic activity of the atomic metal comprises selecting a desired lifetime from among the P(N,M) choices.
22. The method of claim 17 further comprising controlling the oxidation potential of the conductive polymer film.
23. The method of claim 22 , wherein controlling the oxidation potential of the conductive polymer film comprises cycling a potential from −0.2V to +0.7V, then holding the potential at least about +0.8V for at least 30 minutes.