Biomimetic Parallel Vein-like Two-Dimensional Supramolecular Layers Containing Embedded One-Dimensional Conduits Driven by Cation−π Interaction and Hydrogen Bonding to Promote Photocatalytic Hydrogen Evolution

Two-dimensional supramolecular assemblies (2DSAs) with well-defined nanostructures have emerged as promising candidates for diverse applications, particularly in photocatalysis. However, it still remains a significant challenge to simultaneously achieve effective electron transport and multiple active sites in 2DSA, even though this is crucial for enhancing photocatalytic performance. This reason can be attributed to the lack of a suitable structural paradigm that enables both effective intermolecular orbital overlap and increased substrate contact. Inspired by the parallel venation of monocotyledons that can facilitate substrate transfer, we overcome the limitation, in this study, by integrating parallel-arranged one-dimensional (1D) conduits with edge-on packing motifs to construct biomimetic, parallel vein-like two-dimensional supramolecular layers (PV-2DSLs) through the hierarchical self-assembly of cationically modified, rigid multiarmed monomers. The resulting PV-2DSLs exhibit a long-range aromatic cation−π stacking that can facilitate electron transport. Importantly, the unique structural feature of these PV-2DSLs is the orderly and parallel embedding of 1D conduits within the 2D plane, which is significantly different from the conventional channels formed by the vertical stacking of 2D porous materials. These conduits promote multielectron transfer pathways, leading to enhanced charge separation and carrier transport when coupled with long-range aromatic cation−π stacking. As a consequence, these PV-2DSLs exhibit long excited state lifetime, leading to significantly improved hydrogen production rates up to 3.5 mmol g^-1 h^-1, which is approximately 17.5 times higher than that of the counterpart without 1D conduits (0.2 mmol g^-1 h^-1).