Pt<sub>2</sub>Gd Alloy\nNanoparticles from Organometallic\nPt and Gd Complexes and Hollow Mesoporous Carbon Spheres: Enhanced\nOxygen Reduction Reaction Activity and Durability

Pt<sub>2</sub>Gd alloy nanoparticles supported in hollow\nmesoporous\ncarbon spheres (HMCS; <b>Pt</b><sub><b>2</b></sub><b>Gd/HMCS</b>) were successfully prepared by the thermal reduction\nof organometallic Pt and Gd complexes without oxygen atoms supported\nin the pores of HMCS. The structures of Pt<sub>2</sub>Gd alloy nanoparticles\nwere fully characterized by TEM, HAADF-STEM-EDS, XRD, XAFS, and XPS,\nsuggesting the formation of uniform Pt<sub>2</sub>Gd alloy nanoparticles\nwith an average particle size of 5.9 nm. <b>Pt</b><sub><b>2</b></sub><b>Gd/HMCS</b> showed superior oxygen reduction\nreaction activity (2.4 times higher mass-specific activity to Pt nanoparticles\non HMCS (<b>Pt/HMCS</b>)) and remarkable durability even after\nthe 100,000 cycles of accelerated degradation tests compared to <b>Pt/HMCS</b> and a commercial Pt/C catalyst. The structure of the\nPt<sub>2</sub>Gd alloy nanoparticles after initial aging and the durability\ntests suggested that the Pt<sub>2</sub>Gd core–Pt shell structure\nwith a particle size similar to the pore size of HMCS was stably formed\ninside the porous structure of HMCS and maintained under the oxygen-reduction\nworking conditions.