Bimetallic alloy electrocatalysts with multilayered platinum-skin surfaces
Compositions and methods of preparing a bimetallic alloy having enhanced electrocatalytic properties are provided. The composition comprises a PtNi substrate having a surface layer, a near-surface layer, and an inner layer, where the surface layer comprises a nickel-depleted composition, such that the surface layer comprises a platinum skin having at least one atomic layer of platinum.
1. A method of preparing a bimetallic alloy having enhanced electrocatalytic properties, comprising:
synthesizing a PtNi nanoparticle;
depleting a surface of the PtNi nanoparticle of nickel to create a platinum
skeleton; and
smoothing a surface of the platinum skeleton by annealing and creating the PtNi
nanoparticle with multilayered platinum skin surfaces.
2. The method of claim 1 , wherein the step of depleting a surface of the PtNi nanoparticle is achieved by exposing the PtNi nanoparticle to an acidic environment.
3. The method of claim 2 , wherein the acidic environment comprises a pH of at least 1.0.
4. The method of claim 2 , wherein the step of exposing the PtNi nanoparticle to the acidic environment is performed before the step of annealing the PtNi nanoparticle.
5. The method of claim 2 , further comprising the step of incorporating the PtNi nanoparticle on high surface area carbon by colloidal deposition, forming an electrocatalyst.
6. The method of claim 1 , wherein the platinum skin comprises three or less atomic layers of platinum.
7. The method of claim 1 , wherein the step of annealing is conducted at approximately 400 degrees Celsius.
8. The method of claim 7 , wherein the step of annealing is conducted for at least thirty minutes.
9. A method of preparing a platinum-nickel electrocatalyst, comprising:
synthesizing a PtNi nanoparticle;
depleting a surface of the PtNi nanoparticle of nickel by exposing the PtNi nanoparticle to an acidic environment to create a platinum skeleton surface;
smoothing a surface of the platinum skeleton by annealing to create the PtNi nanoparticle with a multilayered platinum skin; and
incorporating the PtNi nanoparticle on high surface area carbon by colloidal deposition.
10. The method of claim 9 , wherein the synthesizing step further comprises heating the PtNi nanoparticle to remove organic surfacants.
11. The method of claim 9 , wherein the platinum skin comprises 3 or less atomic layers of platinum.