Zwitterionic COFs with different acidic groups reconstruct interfacial hydrogen-bond networks and accelerate water dissociation for efficient alkaline hydrogen evolution

Abstract

Rational regulation of the interfacial hydrogen-bond (HB) network to facilitate the rate-determining Volmer step involving water dissociation in alkaline hydrogen evolution reaction (HER) has emerged as a promising yet challenging strategy to break the intrinsic kinetic bottleneck. Herein, three zwitterionic COFs decorated with sulfonate, carboxylate, and phosphonate groups were designed and synthesized as interfacial microenvironment regulators to improve the HB network connectivity at the Pt/C electrode-electrolyte interface, leading to significantly accelerated HER kinetics. Specifically, a combination of in situ Raman spectroscopy, molecular dynamics (MD) simulations, and density functional theory (DFT) calculations demonstrates that COF interfacial regulators effectively disrupt the rigid HB network and induce polarization of interfacial water molecules, leading to a diminished interfacial K+ concentration and a markedly increased fraction of free water, which collectively accelerate interfacial mass transport and water dissociation kinetics. As a result, the optimized Pt/ C@S-IMR catalyst delivers exceptional HER performance, achieving an overpotential of merely 66 mV at 100 mA cm- 2 and a cell voltage of 1.85 V at 1 A cm- 2 with a negligible degradation rate over 400-h in anionexchange membrane water electrolysis (AEMWE). This study not only establishes zwitterionic COFs with different acidic groups as a versatile interfacial engineering strategy to regulate HB connectivity for efficient alkaline HER, but also provides a universal design paradigm for interfacial engineering in electrocatalysis.