PEG crosslinking constructs superhydrophilic S-scheme heterojunction: A novel strategy for highly efficient H2 production over Fe-MOF/C3N5 photocatalyst

Photocatalysis hydrogen production is a sustainable method for generating clean energy from solar power, yet a critical challenge lies in developing photocatalysts with both high activity and facile synthesis. Herein, we propose an innovative interfacial crosslinking strategy, for the first time employing the bifunctional crosslinker CHO-PEG-CHO to mediate the construction of C 3 N 5 /Fe-MOF heterojunctions. Terminal aldehydes of PEG specifically react with amino groups in Fe-MOF and hydroxyl groups in C 3 N 5 to form a stable superhydrophilic PEG@C 3 N 5 /Fe-MOF composite with a remarkable H₂ evolution rate of 4311 μmol·g −1 ·h −1 (7.9 times higher than pure C 3 N 5 ). The exceptional performance originates from the combined effect of a S-scheme charge transfer mechanism for efficient charge separation and optimized redox potentials, and a PEG-enhanced C 3 N 5 -Fe-MOF interaction, validated by time-resolved photoluminescence (PL) alongside transient absorption spectroscopy (TA). This rational crosslinking strategy and elucidated S-scheme pathway provide a new platform for designing highly efficient and stable photocatalysts for solar-driven hydrogen production and broader photocatalytic applications. • The efficient H 2 production photocatalyst C 3 N 5 /Fe-MOF was modified by PEG with a super-hydrophilic surface. • The influence of photo-charge at PEG@C 3 N 5 /Fe-MOF interfaces was studied by time-resolved spectroscopy. • The potential mechanism of H 2 production or enhanced photocatalytic performance of PEG@C 3 N 5 /Fe-MOF is proposed.