3D ordered macro-/mesoporous carbon supported Ag nanoparticles for efficient electrocatalytic oxygen reduction...

Area of Science:

• Materials Science
• Electrochemistry
• Nanotechnology

Background:

• Oxygen reduction reaction (ORR) is crucial for energy conversion technologies.
• Silver nanoparticles (Ag NPs) are promising ORR electrocatalysts but suffer from aggregation and low dispersion.
• Carbon supports play a vital role in enhancing catalyst performance and stability.

Purpose of the Study:

• To prepare and investigate three-dimensionally ordered macro-/mesoporous carbon (OMMC)-supported Ag nanoparticles (Ag/OMMC) as ORR electrocatalysts.
• To compare the ORR performance of Ag/OMMC with Ag nanoparticles supported on conventional carbon black (Ag/XC-72R).
• To elucidate the structure-property relationships governing the enhanced catalytic activity.

Main Methods:

• Synthesis of OMMC material with interconnected macro- and mesopores.
• Impregnation of Ag nanoparticles onto the OMMC support.
• Electrochemical characterization of Ag/OMMC and Ag/XC-72R catalysts for ORR in an alkaline medium.

Main Results:

• Ag/OMMC exhibited smaller Ag particle sizes (4.3 nm) and higher dispersion compared to Ag/XC-72R (6.5 nm).
• Ag/OMMC demonstrated superior ORR activity with a positive half-wave potential of 0.79 V vs. RHE and a higher limiting current density (5.6 mA cm⁻² at 0.4 V).
• The Ag/OMMC catalyst showed enhanced durability, likely due to the prevention of particle aggregation.

Conclusions:

• The unique 3D ordered porous structure of OMMC significantly enhances Ag nanoparticle dispersion and stability.
• Ag/OMMC serves as an effective electrocatalyst for ORR, outperforming traditional carbon supports.
• The improved mass/charge transport and dispersion in the OMMC framework are key to the enhanced ORR performance.