Electron rearrangement at the crystalline-amorphous heterogeneous interface boosts alkaline hydrogen production.

Modifying the platinum (Pt) local reaction microenvironment is a critical and complex challenge in enhancing electrochemical performance. Herein, amorphous Co(OH)₂ and crystalline Pt (labeled as ac-Pt@Co(OH)₂) featuring abundant crystalline-amorphous (c-a) interfaces are designed to boost the hydrogen evolution reaction (HER). The engineered structure creates an advantageous chemical environment at the local level, enhancing hydrogen adsorption efficiency and resulting in exceptional HER performance. The ac-Pt@Co(OH)₂ achieves a low Tafel slope of 28.5 mV dec^-1 and requires merely 95 mV overpotential to reach 200 mA cm^-2 in alkaline electrolyte (1 M KOH), surpassing those of conventional Pt/C catalysts (39.4 mV dec^-1, 256 mV). In situ advanced characterization investigations reveal dynamic electron rearrangement at the c-a interface, where Co species initially accept electrons from Pt to optimize the adsorption of *H species and then donate electrons to Pt for accelerating reduction kinetics. Theoretical calculations reveal that amorphous Co(OH)₂ promotes the dissociation of water molecules to produce active *H, and electron rearrangement at the c-a interface downshifts the d-band center, thereby optimizing the *H adsorption strength and enhancing HER activity. The ac-Pt@Co(OH)₂-based alkaline anion-exchange membrane water electrolyzer (AEMWE) maintains a current density of 500 mA cm^-2 over 500 h.