Ultrafine Nanowires As Highly Efficient Electrocatalysts

Summary

UCLA researchers in the Department of Chemistry and Biochemistry have developed a novel process of synthesizing ultrafine jagged Pt nanowires with a record high utilization efficiency for fuel cell catalyst applications.

Background

Hydrogen fuel cell, with water as the only by-product, is a promising green energy source. Platinum has been used as the catalyst for oxygen reduction reaction (ORR). However, the critical limiting factor for making hydrogen fuel cells economical for transportation is the low Pt catalyst utilization efficiency, i.e. mass activity.

Innovation

Researchers at UCLA designed and synthesized ultrafine jagged Pt nanowires with a record high utilization efficiency of 13.59 A/mgPt, which nearly doubles the highest mass activity value ever reported. The Pt nanowires also exhibit the highest electrochemical active surface area, and high specific activity. These Pt nanowires can also be made in contact with carbon support via multiple points, which promises efficient charge transport and collection. 

Applications

• Electrocatalysts for different reactions:
o Oxygen reduction reaction (for fuel cells, air batteries)
o Oxygen evolution reaction and hydrogen evolution reactions (for water splitting or hydrogen generation)
o CO2 reactions
o N2 reduction reaction (ammonia synthesis),
o Methanol oxidation reaction (MOR).
• The less mobile nanowire catalyst could also offer robust and active catalysts for other important reactions in gas phase
o CO oxidation
o Methane oxidation reaction

Advantages

• Record high utilization efficiency
o Highest electrochemical active surface area
o High specific activity
• Stability using multiple-point contacts with carbon support
o No migration and aggregation during charge cycling
• Possible more efficient charge transport and collection
• Possible acceleration of the reaction speed the Pt catalyst is responsible for

State Of Development

The UCLA researchers have synthesized the ultrafine jagged Pt nanowires and demonstrated experimentally the record high mass activity (13.59 A/mgPt) for oxygen reduction reaction, and robust mass activity (7.9 A/mgPt) for hydrogen evolution reaction. 

Patent Status

Related Materials

• Ruan, L., Zhu, E., Chen, Y., Lin, Z., Huang, X., Duan, X. and Huang, Y. (2013), Biomimetic Synthesis of an Ultrathin Platinum Nanowire Network with a High Twin Density for Enhanced Electrocatalytic Activity and Durability. Angew. Chem. Int. Ed., 52: 12577–12581. doi:10.1002/anie.201304658