Reorganization of interfacial water structure boosted OH− transfer by engineering the charge redistribution and enhanced the alkaline HER

Abstract

The structures of interfacial water and key HER intermediates significantly influence the electrochemical performance of the HER. Herein, a doping strategy was applied to induce charge redistribution within the substrate, which changed the local electron field of the entire catalyst. Boron organic polymers were selected as B and N sources to fabricate Ru NPs dispersed on a BCN substrate (Ru/BCN), which were assembled through Cs₂[closo-B₁₂H₁₂] and 4,4′-bipyridine. In situ surface-enhanced infrared absorption spectroscopy results and density functional theory calculations revealed that the local electron field of the substrate was redistributed via the synergistic effect of B and N, which not only modulated the electron density on Ru sites to decrease the OH⁻ adsorption but also increased the flexibility of the water hydrogen network for aiding OH⁻ transfer. Moreover, the charge redistribution increased the metal-support interaction, boosting the charge transfer efficiency in the HER process. As a result, Ru/BCN required an overpotential of only 17 mV to achieve 10 mA cm⁻². This work provides a new insight into engineering charge redistribution to modulate the structures of interfacial water and key HER intermediates in alkaline HER.