In situ-grown COF/nickel foam heterostructure with interfacial charge transfer enables highly efficient hydrogen...

Achieving efficient hydrogen evolution reaction (HER) in alkaline media remains a fundamental challenge due to the sluggish kinetics of water dissociation. In this study, we introduce an in situ-grown phenolic -OH-rich 2D covalent organic framework (IPREM-COF) with an imine-enamine linkage on a nickel foam (Nif) surface (IPREM-COF@Nif). Here, Nif and IPREM-COF serve as inorganic and organic materials, respectively, where the inorganic-organic interphase electronic mobility results in a significant enhancement of the alkaline HER. A well-defined lattice matching of Ni(111) with the 2D IPREM-COF lattice permits hetero structural (inorganic-organic) correlative electronic modulation for better catalytic performance. Imine (-CN), aminal (-CC-NH-) linkage, and hydroxyl (-OH) functional groups, combined with the Nif substrate, significantly enhance the HER performance under basic conditions, which is crucial for industrial applications. Moreover, under alkaline conditions, during the Volmer step, proton donation can be facilitated by IPREM-COF, which contains phenolic -OH groups capable of serving as internal proton donors. The synergistic interactions between the catalytic active sites of COF and the electron-rich Nif substrate significantly lowers the overpotential, enhancing the HER kinetics in alkaline media, achieving a remarkable overpotential of 56 mV at 10 mA cm^-2, and surpassing the performance of the state-of-the-art Pt/C catalyst. Operando Raman spectroscopy further reveals the potential-induced evolution of the active catalytic species, providing direct mechanistic insights into the enhanced HER activity of IPREM-COF@Nif. Theoretical calculations reveal that a charge of 0.276e is transferred from the IPREM-COF@Nif surface to the adsorbed hydrogen atom, which facilitates the alkaline water splitting process. These findings position IPREM-COF@Nif as a highly promising non-precious electrocatalyst, presenting a viable alternative to noble metals for scalable and sustainable hydrogen production.