Ultralow platinum catalysts for high performance fuel cells: in situ encapsulation of platinum atoms and CoPt3 in 3D hollow nanoshells

Abstract

Reducing the use of platinum is urgently needed while maintaining the activity and stability in proton exchange membrane fuel cells (PEMFCs). Currently, single-atom platinum (Pt SA) catalysts are greatly developed and show substantially increased catalytic activity. However, most reports show that small and highly exposed Pt nanoparticles have rapid degradation issues. Here, we employ a method of confining Pt SAs and CoPt₃ alloy nanoparticles (NPs) within three-dimensional (3D) hollow nanoshells to obtain high activity and durability in ultra-low Pt-loaded Pt SAs/CoPt₃@NC catalysts. The catalyst is formed by in situ reduction of platinum in a fresh metal framework reserve solution, followed by segmented calcination in a reducing atmosphere. What's exciting is that the Pt SAs/CoPt₃@NC mass activity was measured to be 1.323 A cm_Pt⁻¹ at 0.9 V and 13.5 times more than commercial Pt/C mass activity as well as exceeding the Department of Energy (DOE) 2025 (0.44 A cm_Pt⁻¹) activity targets. Besides, the half-cell shows only 2.3% loss of mass activity after 30 000 cycles, which is higher than those of most reported noble metal catalysts. More importantly, the single cell demonstrates ultra-high durability, reaching 0.9635 W cm⁻² even after 30 000 cycles. There is great potential for ultralow Pt catalysts to replace commercial Pt/C catalysts.