Single-atom Cu in TCPP-hydrogen-bonded organic framework/PFC-1 hydrogen-bonded organic framework Z-scheme heterojunctions for photocatalytic hydrogen production

HOF/HOF-based Z-scheme heterojunctions were successfully synthesized. • Z-scheme heterojunctions and Cu single atoms boost charge separation. • TCPP(M)-HOF/PFC-1 exhibits the highest H 2 evolution rate of 42.7 mmol g −1  h −1 . Hydrogen-bonded organic frameworks (HOFs) have exhibited extraordinarily broad application prospects in the field of photocatalysis owing to their unique structural merits. Nevertheless, pristine HOF materials generally suffer from the bottleneck of low separation efficiency for photogenerated charge carriers, which severely restricts their practical industrial applications in photocatalysis. To address this issue, herein we have successfully constructed a series of Z -scheme heterojunction photocatalysts based on the two-dimensional HOF/HOF system (denoted as TCPP (H or M)-HOF/PFC-1, where M = Cu, Zn, Ni), with the targeted composite heterostructure fabricated from TCPP(Cu)-HOF and PFC-1 HOF as the core product. Among them, the porphyrin-based TCPP(Cu)-HOF effectively broadens the spectral response range of light absorption for the composite; the precise construction of the Z -scheme heterojunction greatly enhances the separation and transport efficiency of photogenerated charges; meanwhile, the single-atom Cu sites (Cu-SA) can significantly shorten the charge migration pathway and accelerate the directional and rapid transfer of photogenerated electrons, ultimately enabling the efficient conversion of solar energy into chemical energy. Furthermore, the excellent energy level matching between TCPP(Cu)-HOF and PFC-1 HOF in the composite, coupled with the synergistic regulation of single-atom active sites, further facilitates the efficient directional migration of photogenerated charge carriers. Experimental test data confirm that the optimized TCPP(Cu)-HOF/PFC-1 heterojunction photocatalyst delivers a photocatalytic hydrogen evolution rate of up to 42.7 mmol·g −1 ·h −1 . This work fully demonstrates the outstanding advantages of HOF/HOF Z -scheme heterostructures in precisely tailoring photogenerated charge carrier dynamics, providing a novel and feasible research strategy for efficiently boosting photocatalytic hydrogen evolution performance and designing high-performance heterojunction catalysts for solar energy conversion. Here, we present a Z -scheme heterojunction photocatalyst based on two-dimensional HOF/HOF composites, specifically TCPP(M)-HOF/PFC-1 (M = Cu, Zn, Ni), with TCPP(Cu)-HOF and PFC-1 HOF as the representative system. Owing to the favorable energy level alignment between the two HOF components and the introduction of single-atom Cu sites, the directional migration of photogenerated charge carriers is significantly enhanced. Download: Download high-res image (117KB) Download: Download full-size image