Highly crystalline multimetallic nanoframes with three-dimensional electrocatalytic surfaces

Area of Science:

• Materials Science
• Electrochemistry
• Nanotechnology

Background:

• Precise control over atomic structure is key to tuning material properties.
• Developing highly active and durable electrocatalysts is crucial for energy applications.
• Platinum-nickel (Pt-Ni) bimetallic nanocrystals offer tunable catalytic properties.

Purpose of the Study:

• To synthesize and characterize a new class of Pt-Ni bimetallic electrocatalysts.
• To investigate the structural evolution of Pt-Ni nanocrystals for enhanced catalytic performance.
• To evaluate the activity and durability of the resulting nanostructures for the oxygen reduction reaction (ORR).

Main Methods:

• Synthesis of crystalline PtNi3 polyhedra.
• Controlled structural transformation in solution to form Pt3Ni nanoframes via interior erosion.
• Characterization of the nanoframe structure and surface properties.
• Electrochemical evaluation of the oxygen reduction reaction (ORR) activity and durability.

Main Results:

• PtNi3 polyhedra transformed into Pt3Ni nanoframes with open frameworks and 3D molecular accessibility.
• The nanoframe surfaces featured a nanosegregated Pt-skin structure.
• The Pt3Ni nanoframe catalysts demonstrated a 36-fold increase in mass activity and a 22-fold increase in specific activity for ORR compared to Pt-C catalysts.
• Enhanced durability was observed during prolonged electrochemical testing.

Conclusions:

• The structural evolution of Pt-Ni nanocrystals yields highly active and durable electrocatalysts.
• The Pt3Ni nanoframe structure with its Pt-skin surface is effective for improving oxygen reduction reaction (ORR) performance.
• This approach offers a pathway for designing advanced electrocatalysts for energy conversion technologies.