▎ 摘　　要

Ultralow platinum loading and high electrocatalytic performance at the cathode are critical to lower costs of proton-exchange membrane fuel cells (PEMFCs). Encaging platinum catalysts into pore channels by geometric constraints and chemical interactions can orchestrate spatial organization, stabilize multitype sites, minimize platinum loading, and resist surface poisoning. Here, we report the design and synthesis of encaging platinum single atoms and ultrafine nanoparticles to periodic nanopores of three-dimensional graphene-like architecture carbon by a transformative strategy. The PEMFC with such unique cathodic configuration at an ultralow platinum loading of 0.02 mgPt cm-2 exhibits a superior mass activity of 8.30, 1.64 times that of commercial Pt/C, DOE 2025 activity target, respectively, and a great stability with a power density retention of 70.8% after the longterm stability test. This work offers an insight into the design of unique confinement electrocatalysts for electrochemical energy technologies and the industrial implementation of fuel cells.