Rational Design of Carbon-Supported Platinum–Gadolinium Nanoalloys for Oxygen Reduction Reaction

Highly active and long-term stable electrocatalysts for the oxygen reduction reaction (ORR) of proton-exchange membrane fuel cells are required for alignment of material properties with sectoral demand. Herein, we have produced a series of Pt x Gd/C electrocatalysts using the carbodiimide complex route, in which the gadolinium content in the final product was systematically varied. The results reveal that the Pt/Gd ratio influences the crystalline structure, the particle size, the near-surface chemistry, and, therefore, the electrochemical activity toward ORR. A morphological transition, from solid nanoparticles to porous architecture, takes place as the Gd concentration increases, where 10 nm is the critical size for transition. Moreover, the mass activity toward the ORR displays a volcano-shaped trend, reaching a maximum value at the composition of Pt 4.7 Gd. This contribution identifies key properties of the Pt x Gd/C nanostructures that are essential to boost the ORR activity and durability, along with remaining issues that must be addressed, such as the undesirable formation of porous architecture.