Engineering of MnO₂-RuO₂ for efficient alkaline hydrogen evolution reaction and stable ampere-level anion exchange...

Developing high-efficiency and ultrastable electrocatalysts is critical for advancing anion exchange membrane water electrolyzer (AEMWE) to industrial ampere-level operation. Herein one type of MnO₂-RuO₂ heterostructure catalyst is fabricated, which displays outstanding alkaline hydrogen evolution reaction (HER) activity, achieving a low overpotential of 22 mV (10 mA cm^-2) and small Tafel slope of 29.7 mV dec^-1. Comprehensive experimental characterizations (cs-HRTEM, electrochemical in situ FTIR, operando EIS and SECM) combined with theoretical simulations (DFT, AIMD) reveal that the MnO₂-RuO₂ heterostructure can efficiently reduce H₂O dissociation energy barrier (0.045 eV → 0.33 eV of pure RuO₂); meanwhile, the MnO₂ can modulate d-band center of Ru active sites, thereby modify the intermediates (H* and OH*) adsorption/desorption ability and thus accelerate reaction kinetics. Benefiting from the constructed MnO₂-RuO₂ heterostructure, the assembled AEMWE with MnO₂-RuO₂ cathode and NiFe-layered double hydroxide (NiFe-LDH) anode achieves a low cell voltage of 1.91 V at 1000 mA cm^-2 and maintains stable operation for over 100 h without significant performance degradation. Generally, this work provides a promising MnO₂-RuO₂ heterojunction catalyst with excellent performance for alkaline HER and high-current-density AEMWE application, which also offers new insights into the rational design of catalytic local environments through heterostructure engineering.