Dataset for "Distance-Programmed Metal−Organic Layers Regulate Interfacial Water to Accelerate Hydrogen Evolution"

Interfacial water structure critically affects hydrogen evolution reaction (HER) in neutral and alkaline media, where sluggish water dissociation limits the Volmer step. Here we report a distance-programmed metal–organic layer (MOL) that is laid directly on metal electrode surfaces to regulate the near-surface microenvironment in HER. The vertical separation between the Hf6(μ3-O)4(μ3-OH)4 building units of the MOL and the underlying metal surface can be systematically tuned by post-synthetic ligand exchange on the MOL surface. Under operating conditions, deprotonation of μ3-OH on the Hf6(μ3-O)4(μ3-OH)4 cluster generates arrays of μ3-O⁻ groups that can electrostatically enrich hydrated alkali cations at the metal–electrolyte interface. In situ Infrared spectroscopy showed that interfacial water reorganized after MOL loading, from strongly hydrogen-bonded networks toward weakly bound, H-down configurations favorable for O–H bond cleavage. Shorter MOL–metal distances markedly amplify this effect, leading to accelerated hydrogen evolution kinetics. On Pt electrodes, optimized spacing reduces the overpotential at 10 mA·cm-2 by over 100 mV relative to bare metal. The enhancement persists across a broad pH range (3–13) and generalizes across multiple metal substrates including Cu, Au, W, Co, and Ni. These results establish surface-laid, distance-defined MOLs as an interesting tool to study interfacial water structure and electrochemical kinetics through spatially programmed electrostatics.