Impact of carbon supports on the Pt-based catalyst activity and fuel cell performance under varied operational conditions

• A one-pot method is used to prepare Pt nanoparticles on various carbon supports. • Pt particles are characterized to be uniformly deposited with the size of 2 ∼ 3 nm. • Half and single-cell tests are performed to evaluate the catalytic performance. • Incorporating graphene into Ketjen black facilitates gas convection and diffusion. • A high peak power density of 1.17 W/cm 2 is achieved under 100 % relative humidity. Proton exchange membrane fuel cells (PEMFCs) play a pivotal role in advancing sustainable energy systems, with catalysts serving as critical components for their effectiveness and efficiency. While commercial Pt/C catalysts have made significant contributions, further improvements are still needed to meet the evolving requirements. Current methods for synthesizing high-performance catalysts often focus on composition design, morphology control and surface modification, while they face limitations related to the complicated preparation process and scalability. To address these issues, a facile one-pot synthesis approach is developed to prepare Pt nanoparticles on the Ketjenblack EC-600JD (Pt/Ket600), graphene nanoplatelets (Pt/GNP) and mixture of Ket600 and GNP (Pt/Ket600/GNP). The incorporation of GNP into Ket600 optimizes the structural properties of the carbon support, providing an effective platform for better dispersion of Pt nanoparticles. The high scalability of the proposed synthesis method yields over 750 mg of catalyst per batch, ensuring its applicability for large-scale production. As expected, Pt/Ket600/GNP demonstrates an optimal morphological structure, with Pt nanoparticles uniformly distributed with an average size of 2.15 nm and an overall Pt loading of approximately 46 %. The as-prepared Pt/Ket600/GNP also exhibits reduced permeation and diffusion resistivity, along with 1.26- and 1.68-fold higher mass activity for the oxygen reduction reaction, compared to Pt/Ket600 and Pt/GNP, respectively. The membrane electrode assembly with the Pt/Ket600/GNP catalyst achieves a peak power density of 1.17 W/cm 2 when operating on fully humidified hydrogen and air at 75 °C and 35 kPaG. This impressive performance highlights its strong potential for practical PEMFC applications.