Interfacial water reconstruction in high-entropy alloys breaks thermodynamic scaling relations for hydrogen evolution

The alkaline hydrogen evolution reaction (HER) is governed by the kinetic incompatibility between water dissociation and hydrogen adsorption. The conventional Pt-based catalysts are further limited by thermodynamic scaling relations that hinder the concurrent optimization of the Volmer and Tafel steps. Herein, we report a hexanary PtFeNiCoMoPd@rGO (reduced graphene oxide, rGO) high-entropy alloy (HEA) that introduces a localized electronic polarization field to regulate the interfacial water microenvironment. Density functional theory (DFT) calculations show that multimetallic integration upshifts the Pt d-band center and yields a near-thermoneutral hydrogen adsorption free energy (ΔG_H⁎ = -0.080 eV). Mechanistically, Ni and Mo sites promote water dissociation, while Fe, Co, and Pd tune the electronic structure of Pt domains to balance H* adsorption and H₂ desorption. The optimized PtFeNiCoMoPd@rGO-500 catalyst delivers 10 mA cm^-2 at an overpotential of 13 ± 1.7 (n = 3) mV with a Tafel slope of 15 ± 2.0 (n = 3) mV dec^-1, outperforming commercial Pt/C (35 mV and 38 mV dec^-1, respectively). In addition, it exhibits a mass activity of 2.7 A mg^-1 and stable operation for over 100 h. In situ Raman spectroscopy further reveals that the catalyst induces a transition of interfacial water from a disordered state to an active four-fold hydrogen-bonded network. These results highlight atomic-level polarization engineering as an effective strategy to break the scaling limitations of alkaline HER.