Coupling Single-Ni-Atom with Ni-Co Alloy Nanoparticle for Synergistically Enhanced Oxygen Reduction Reaction

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Developing efficient nonprecious metal electrocatalysts is vital for commercializing proton-exchange membrane (PEM) fuel cells.
• The oxygen reduction reaction (ORR) is a key bottleneck in fuel cell performance.

Purpose of the Study:

• To design and synthesize a novel metal-organic framework (MOF)-derived N-doped hollow carbon structure (NiCo/hNC) for ORR catalysis.
• To investigate the structure-activity relationship and performance of NiCo/hNC in both alkaline and acidic electrolytes and in PEM fuel cells.

Main Methods:

• Synthesis of a unique N-doped hollow carbon structure (NiCo/hNC) from MOFs.
• Characterization of the catalyst structure, including atomically dispersed single-Ni-atom (NiN4) and NiCo alloy nanoparticles (NPs).
• Density functional theory (DFT) calculations to understand the ORR mechanism and electronic structure.

Main Results:

• NiCo/hNC exhibits highly efficient and durable ORR catalysis in both alkaline and acidic media.
• DFT calculations reveal strong coupling between NiN4 sites and NiCo NPs, facilitating a direct 4e- transfer ORR pathway.
• NiCo/hNC demonstrated stable performance as a cathode electrode in PEM fuel cells.

Conclusions:

• The developed NiCo/hNC catalyst offers a promising nonprecious metal alternative for ORR.
• Understanding the synergistic effects between single-atom sites and alloy nanoparticles is crucial for designing advanced electrocatalysts.
• This work provides fundamental insights for developing next-generation ORR catalysts for fuel cell applications.