Sequential construction of HOF-on-HOF architectures via stepwise hemin immobilization toward enhanced photocatalytic hydrogen evolution

A facile sequential crystallization strategy is developed to fabricate isostructural HOF-on-HOF architectures with periodic interfacial lattice contrast. • Spatially stepwise immobilization of hemin across core and shell regions extends visible-light harvesting and provides reversible Fe(III)/Fe(II) redox sites. • The optimized LPFC-1@hemin@NPFC-1@hemin catalyst achieves a hydrogen evolution rate of 2345.1 μmol·g −1 ·h −1 under visible light (λ ≥ 420 nm), 1.84-fold higher than pristine LPFC-1. • The synergistic effect of interfacial charge regulation and hemin sensitization opens a new avenue for high-performance HOF-based photocatalyst design. Hydrogen-bonded organic frameworks (HOFs) have emerged as promising photocatalysts for sustainable hydrogen production, yet their performance suffers from intrinsically poor visible-light absorption and sluggish photogenerated carrier transfer kinetics. To address these issues, we herein report a facile sequential crystallization strategy to construct isostructural HOF-on-HOF materials, wherein a periodic interfacial lattice contrast spontaneously forms at the core-shell boundary. Moreover, this kind of structure further enables stepwise immobilization of hemin molecules in both the core and shell domains via hydrogen bonding and π···π stacking interactions. Benefiting from the synergistic effects between periodic interfacial lattice contrast and hemin immobilization, the optimal LPFC-1@hemin@NPFC-1@hemin (large-sized pyrene-based hydrogen-bonded organic frameworks, denoted as LPFC-1, nano-sized pyrene-based hydrogen-bonded organic frameworks, denoted as NPFC-1) catalyst exhibits an exceptional photocatalytic hydrogen evolution rate of 2345.1 μmol·g −1 ·h −1 under visible light irradiation (≥ 420 nm), which is 1.84 times higher than that of pristine LPFC-1. This work not only establishes a robust strategy to construct continuous HOF crystalline layers on preformed HOF crystals, but also presents an efficient route for stepwise hemin immobilization toward boosted photocatalytic hydrogen evolution. A stepwise layered growth strategy constructs well-defined HOF-on-HOF materials and achieves spatial immobilization of hemin for superior photocatalytic hydrogen generation. Download: Download high-res image (255KB) Download: Download full-size image