Methods for forming electrocatalyst structures and electrodes comprising same
Described herein are methods of forming an electrocatalyst structure on an electrode, comprising depositing a first layer on the electrode using atomic layer deposition (ALD), wherein the first layer comprises a plurality of discrete nanoparticles of a first electrocatalyst, and depositing one or more of a second layer on the first layer and the electrode using ALD, wherein the one or more second layer comprises a second electrocatalyst, wherein the first layer and the one or more second layers, collectively, form a multi-layer electrocatalyst structure on the electrode. Also described are electrodes having a multi-layer electrocatalyst structure. This abstract is intended as a scanning tool for purposes of searching in the particular art and is not intended to be limiting of the present disclosure.
1. A method of forming an electrocatalyst structure on an electrode, comprising:
depositing a first layer on the electrode using atomic layer deposition (ALD), wherein the first layer comprises a plurality of discrete nanoparticles of a first electrocatalyst; and
depositing one or more of a second layer on the first layer and the electrode using ALD, wherein the each of the one or more second layers independently comprises a second electrocatalyst; and
wherein the first layer and the one or more second layers collectively form a deposited electrocatalyst structure on the electrode;
subjecting the electrode to electrochemical operation at a temperature equal to or greater than about 650° C., thereby transforming deposited electrocatalyst structure to an operated electrocatalyst structure.
2. The method of claim 1 , wherein the first electrocatalyst comprises a noble metal.
3. The method of claim 2 , wherein the first electrocatalyst comprises platinum (Pt).
4. The method of claim 1 , wherein the discrete nanoparticles of the deposited electrocatalyst structure have an average particle size of less than about 200 nanometers in the largest dimension.
5. The method of claim 1 , wherein the second electrocatalyst comprises an electronically conducting material that has catalytic activity for ORR.
6. The method of claim 1 , wherein the second electrocatalyst comprises a metal oxide comprising one or more transition metals.
7. The method of claim 1 , wherein the second electrocatalyst comprises a metal oxide comprising manganese, cobalt, or both, having the formula (Mn 1-y Co y ) 3 O 4 , wherein y has a value from 0.0 to 1.0.
8. The method of claim 1 , wherein each of the one or more second layers of the deposited electrocatalyst structure, independently, has a thickness of from about 1 nanometers to about 200 nanometers.
9. The method of claim 1 , wherein the subjecting the electrode to electrochemical operation results in a plurality of pores or fissures extending through a thickness of the second layer.
10. The method of claim 1 , wherein the subjecting the electrode to electrochemical operation results in the formation of a plurality of discrete nanograins of the second electrocatalyst separated by intergranular grain boundaries.
11. The method of claim 1 , wherein the subjecting the electrode to electrochemical operation results in the formation of a plurality of triple phase boundaries at intergranular grain boundaries.
12. The method of claim 1 , wherein the subjecting the electrode to electrochemical operation results in at least a portion of the plurality of the nanoparticles of the first electrocatalyst populating adjacent one or more of triple phase boundaries at intergranular grain boundaries.
13. The method of claim 1 , wherein the subjecting the electrode to electrochemical operation results in the formation of a plurality of coupled grains comprising one of the plurality of nanoparticles of the first electrocatalyst, and a nanograin of the second electrocatalyst.
14. The method of claim 1 , wherein the subjecting the electrode to electrochemical operation results in the formation of a plurality of core-shell nanostructures, each core-shell nanostructure comprising a core comprising a nanoparticle of the first electrocatalyst, that is at least partially covered by a shell comprising the second electrocatalyst.