Technologies Available for License

2012-040: Nitride Stabilized Core-Shell Nanoparticles

Invention: 2012-040

Patent Status: U.S. Patent Number 9,882,222 was issued on January 30, 2018

For technical and licensing related questions, email tcp@bnl.gov.

Summary

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A) Comparison of surface strain versus predicted binding energy of oxygen (BE-O) on the Pt₂MLNi₄N and Pt nanoparticle models with ~1.7 nm. (B) Pt specific activity against BE-O on PtNiN/C and Pt/C. (C) Schematic of the inner Pt diffusion process to the defective sites at the vertex during cycling in the electrolyte. For clarity, the inner Pt atoms involved in diffusion are described in green, while the defects are in yellow.

Polymer electrolyte membrane (PEM) fuel cells offer exciting possibilities as alternative energy sources. The limiting reaction in these fuel cells is the oxygen reduction reaction (ORR) for which platinum is the best catalyst. Great strides have been made in reducing the overall amount of Pt required, and thus reducing the cost of the fuel cell, by coating a base metal nanoparticle core with a monolayer shell of Pt. Nevertheless, under voltage cycling conditions, as would be found in start-stop driving in a fuel cell electric vehicle, the core can dissolve, leaving the Pt shell vulnerable to dissolution itself. This invention addresses the challenge by stabilizing the core material against dissolution in the extremely acidic environment of a PEM fuel cell. During accelerated testing the stabilized core-shell nanocatalysts showed minimal (11mV) loss in half-wave potential over 35,000 cycles. The nanocatalysts also showed higher mass and specific activity than commercially available Pt/carbon catalysts.

Description

Nitride stabilized metal nanoparticles and methods for their manufacture are disclosed. In one embodiment the metal nanoparticles have a continuous and nonporous shell with a nitride-stabilized metal core. The nitride-stabilized core provides a stabilizing effect under high oxidizing conditions suppressing the noble-metal dissolution during potential cycling. The nitride stabilized nanoparticles may be fabricated by a process in which a core is coated with an ultrathin shell layer that encapsulates the entire core. Introduction of nitrogen into the core by annealing produces metal nitride(s) that are less susceptible to dissolution during potential cycling under high oxidizing conditions.

Journal Publication & Intellectual Property

• Nitride Stabilized PtNi Core Shell Nanocatalyst for high Oxygen Reduction Activity (.pdf)
• US 9,882,222 (.pdf)
• US 10,501,321 (.pdf)
• US 10,680,249 (.pdf)