Journal
ADVANCED MATERIALS
Volume 34, Issue 26, Pages -Publisher
WILEY-V C H VERLAG GMBH
DOI: 10.1002/adma.202202743
Keywords
durability; ligand carbonization; membrane electrode assembly; oxygen reduction reaction; platinum nanoparticles
Categories
Funding
- National Key Research and Development Program of China [2020YFB1505803]
- NSFC [22025501, 21872038, 21733003, 51773042, 51973040, 52003056]
- Shanghai International Science and Technology Cooperation Project [21520713800]
- Foshan Science and Technology Innovation Program [2017IT100121]
Ask authors/readers for more resources
This study presents a method to enhance the durability of Pt nanoparticles by converting the surface ligands into ultrathin graphitic shells through thermal annealing. The annealing temperature plays a critical role in determining the ORR performance of Pt catalysts, with Pt nanoparticles annealed at 700 degrees C showing high activity and exceptional stability. The graphitic-shell-coated Pt catalysts exhibit superior ORR stability and can be applied in designing durable catalysts for fuel cells.
Current protocols for synthesizing monodisperse platinum (Pt) nanoparticles typically involve the use of hydrocarbon molecules as surface-capping ligands. Using Pt nanoparticles as catalysts for the oxygen reduction reaction (ORR), however, these ligands must be removed to expose surface sites. Here, highly durable ORR catalysts are realized without ligand removal; instead, the native ligands are converted into ultrathin, conformal graphitic shells by simple thermal annealing. Strikingly, the annealing temperature is a critical factor dictating the ORR performance of Pt catalysts. Pt nanoparticles treated at 500 degrees C show a very poor ORR activity, whereas those annealed at 700 degrees C become highly active along with exceptional stability. In-depth characterization reveals that thermal treatment from 500 to 700 degrees C gradually opens up the porosity in carbon shells through graphitization. Importantly, such graphitic-shell-coated Pt catalysts exhibit a superior ORR stability, largely retaining the activity after 20 000 cycles in a membrane electrode assembly. Moreover, this ligand carbonization strategy can be extended to modify commercial Pt/C catalysts with substantially enhanced stability. This work demonstrates the feasibility of boosting the ORR performance of common Pt nanoparticles by harnessing the native surface ligands, offering a robust approach of designing highly durable catalysts for proton-exchange-membrane fuel cells.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available