Engineering the Low Coordinated Pt Single Atom to Achieve the Superior Electrocatalytic Performance toward Oxygen...

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Developing cost-effective and high-performance catalysts is crucial for fuel cell applications.
• Single-atom catalysts (SACs) offer high atom utilization efficiency and unique catalytic properties.
• Metal-organic framework (MOF)-derived nitrogen-doped carbon (NC) materials are promising supports for SACs.

Purpose of the Study:

• To synthesize platinum single-atom catalysts (Pt SACs) on MOF-derived NC supports using atomic layer deposition (ALD).
• To investigate the structure-activity relationship of Pt catalysts with varying sizes (single atoms to nanoparticles).
• To evaluate the electrocatalytic performance of Pt SACs for the oxygen reduction reaction (ORR).

Main Methods:

• Atomic layer deposition (ALD) was employed to synthesize size-controlled Pt catalysts on MOF-derived NC.
• X-ray absorption fine structure (XAFS) spectroscopy was used to characterize the electronic structure and coordination environment of Pt.
• Density functional theory (DFT) calculations were performed to understand the anchoring sites and reaction mechanisms.

Main Results:

• Pt SACs with Pt-N coordination and increased electron vacancy were successfully synthesized.
• Pt SACs exhibited a 6.5-fold higher mass activity for ORR compared to Pt nanoparticle catalysts.
• DFT calculations confirmed pyridinic N-doped carbon sites as preferred anchoring sites for Pt single atoms.

Conclusions:

• ALD is an effective strategy for fabricating Pt SACs on MOF-NC supports with tunable sizes.
• The enhanced ORR activity of Pt SACs is attributed to the low-coordination environment and electronic structure modulation.
• Pt SACs demonstrate superior activity and stability, making them promising for fuel cell applications.