Decoupling Zeolite-Confined Hydrated Protons from Bulk Alkalinity for Efficient Hydrogen Evolution.

The scarcity of protons in alkaline media limits many proton-coupled energy conversion processes, particularly the hydrogen evolution reaction (HER). Here, we introduce a strategy to create a confined acidic microenvironment within strongly alkaline solution. Ultramicroporous Brønsted acidic zeolites stabilize hydrated protons through a size-exclusion effect, in the presence of bulky quaternary ammonium bases. In situ diffuse reflectance infrared Fourier transform spectroscopy and first-principles simulations reveal that confined protons derived from Brønsted acid sites migrate into the hydrogen-bond network of water, forming a Zundel-Eigen continuum that supports Grotthuss transport. Complementary inelastic neutron scattering and solid-state nuclear magnetic resonance confirm the persistence of hydrated protons under highly alkaline conditions. Guided by this principle, we developed a composite catalyst combining proton-donating nanoparticles with active, conductive layers, which delivers a 19-25% reduction in overpotential, a 20-fold enhancement in Pt mass activity, and accelerated kinetics compared with commercial Pt/C. These findings establish a broadly applicable framework for decoupling local proton activity from bulk pH, opening new pathways for HER and other proton-coupled reactions in alkaline environments.