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

Abstract

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.