Interlayer-engineering of covalent organic framework -confined superlattice for enhanced hydrazine-assisted seawater splitting.

Van der Waals superlattice heterostructures assembled by integrating diverse single-layer two-dimensional (2D) nanosheets, can synergistically combine the advantages of individual layers offering a promising strategy for highly efficient electrocatalytic hydrogen evolution. Here, a heterostructure with a well-order superlattice of alternating monolayer Ni-doped 1 T-MoS2 and amidated guanidinium-based covalent organic framework (A-DhaTG) nanosheets was constructed on carbon cloth (CC) through an interlayer confinement strategy (A-DhaTG/1 T-MoS2/NiS/CC). The guanidine- and hydroxyl-rich A-DhaTG not only constructs efficient hydroxide ion (OH-) transport channels but also endows the material with outstanding superhydrophilicity, which significantly promote the rapid desorption of small-sized bubbles (70-130 μm). When applied to hydrazine-assisted water electrolysis, the rapid miss/gas transport capabilities and abundant active sites, enable the A-DhaTG/1 T-MoS2/NiS/CC superlattice heterojunction to demonstrate exceptional hydrogen evolution reaction (HER) and hydrazine oxidation reaction (HzOR) activity. With the A-DhaTG/1 T-MoS2/NiS/CC-assembled two-electrode system, a current density of 0.1 A cm-2 can be achieved at 0.351 V, substantially outperforming conventional water electrolysis, with excellent long-term stability. This study provides new insights into the design of two-dimensional van der Waals superlattice heterostructures incorporating COFs, while demonstrating the promoting effect of interlayer porous structures on gas evolution reaction.