Dense Heterointerfaces and Unsaturated Coordination Synergistically Accelerate Electrocatalysis in Pt/Pt5P2 Porous Nanocages

Designing cost‐effective and durable Pt‐based catalysts is vital and challenging for practicable energy storage and conversion technologies. Here, a fast phosphating strategy to establish a Pt/Pt5P2 porous nanocage with numerous heterointerfaces and defects is presented. It exhibits extraordinary activity and stability for both hydrogen evolution reaction (HER) with a small overpotential of 29 mV at 10 mA cm−2 and methanol oxidation reaction (MOR) with a high mass activity of 1.37 A mg−1Pt at peak values, surpassing Pt/C. Microstructural analyzes show that many stacking faults are induced around heterointerfaces, while rich vacancies and atomic steps are created by the phosphorus‐induced thermal migration of Pt atoms, serving as highly active low‐coordination sites. X‐ray absorption spectroscopy and theoretical calculations reveal that introducing P atoms can modify the electronic configuration of Pt, thus optimizing H2O/H* binding strength and lowering water dissociation energy to accelerate HER, while decreasing the energy barrier of the rate‐limiting step (*CHO to *HCOOH) to facilitate MOR. The Pt/Pt5P2 porous nanocage is fabricated via a fast phosphating strategy for accelerating electrocatalysis.