Pt2Gd Alloy Nanoparticles from Organometallic Pt and Gd Complexes and Hollow Mesoporous Carbon Spheres: Enhanced Oxygen Reduction Reaction Activity and Durability

Pt2Gd alloy nanoparticles supported in hollow mesoporous carbon spheres (HMCS; Pt2Gd/HMCS) were successfully prepared by the thermal reduction of organometallic Pt and Gd complexes without oxygen atoms supported in the pores of HMCS. The structures of Pt2Gd alloy nanoparticles were fully characterized by TEM, HAADF-STEM-EDS, XRD, XAFS, and XPS, suggesting the formation of uniform Pt2Gd alloy nanoparticles with an average particle size of 5.9 nm. Pt2Gd/HMCS showed superior oxygen reduction reaction activity (2.4 times higher mass-specific activity to Pt nanoparticles on HMCS (Pt/HMCS)) and remarkable durability even after the 100,000 cycles of accelerated degradation tests compared to Pt/HMCS and a commercial Pt/C catalyst. The structure of the Pt2Gd alloy nanoparticles after initial aging and the durability tests suggested that the Pt2Gd core–Pt shell structure with a particle size similar to the pore size of HMCS was stably formed inside the porous structure of HMCS and maintained under the oxygen-reduction working conditions.