Dynamic Dissolution‐Deposition Equilibrium Enables Unprecedented HER Stability in Acidic PEMWE

Abstract Proton exchange membrane water electrolysis (PEMWE) holds substantial promise for effectively utilizing renewable energy to produce green hydrogen. However, it faces critical durability challenges due to acid‐driven catalyst degradation under intermittent renewable power. Here, this study reports a dynamic dissolution‐deposition equilibrium that achieves exceptional hydrogen evolution reaction (HER) stability through rational design of a high‐entropy alloy‐derived architecture. Dealloying FeCoNiNbPt HEA creates a porous scaffold with dual‐functional components: an amorphous NbOx buffer suppressing metal dissolution, while multicomponent Pt 3 (FeCoNi) nanocrystals synergistically enhancing HER activity (137 mV@1 A cm −2 , 2.5 × lower than Pt/C) that thermodynamically favors redeposition. This dynamic self‐adaptive mechanism maintains equilibrium under harsh operating conditions, demonstrating exceptional durability (>2200 h @1 A cm −2 and 1 000 000 cycles). The self‐supported catalysts can be easily mass‐produced with 8.87 wt.% Pt loading (60% reduction vs Pt/C), indicating its industrial applicability. The equilibrium‐driven design paradigm opens new avenues for industrial proton‐exchange‐membrane devices operating under fluctuating power.