Kinetic-oriented design of pyrrolic-N induced Ni and C dual sites for exceptional H2O dissociation and alkaline HER

Due to the sluggish water dissociation in the alkaline hydrogen evolution reaction (HER), the developed electrocatalysts are crucial for enhanced water electrolysis. Herein, we present the nickel metal confined in pyrrolic-N-rich carbon nanoplates (Ni@NCP) for efficient alkaline HER. Benefiting from the polydopamine-derived pyrrolic-N-rich carbon, the uniformly distributed nickel nanoparticles maximize the electrocatalytic sites and are stable without severe corrosion under alkaline media. The in-situ and ex-situ analyses and density functional theory demonstrate that the pyrrolic-N modulates the Ni and C as dual active sites to facilitate the cleavage of the HO-H bond and the proton spillover, resulting in an acceleration of water dissociation and HER kinetics. As a result, Ni@NCP exhibits a low overpotential of 42 mV at 10 mA/cm2 current density and a Tafel slope of 94.9 mV/dec. This study not only provides insights into the structure-properties relationships, also emphasizes the importance of kinetically designing for various electrocatalytic applications. [Display omitted] •Ni@NCP was obtained by the reduction of PDA-coated novel 2D Ni Hofmann-type MOF.•N-functional-rich PDA serves sufficient pyrrolic-N on carbon substrate.•Pyrrolic-N-modified Ni and C sites optimized H2O, OH* and H* intermediates.•Dual active sites effectively facilitate the HO-H cleavage and H2O dissociation.•Kinetic-oriented design of Ni@NCP efficiently enhances the H+ spillover.