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; <b>Pt</b>_<b>2</b><b>Gd/HMCS</b>) 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. <b>Pt</b>_<b>2</b><b>Gd/HMCS</b> showed superior oxygen reduction reaction activity (2.4 times higher mass-specific activity to Pt nanoparticles on HMCS (<b>Pt/HMCS</b>)) and remarkable durability even after the 100,000 cycles of accelerated degradation tests compared to <b>Pt/HMCS</b> 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.