Bonding-site-locked interfacial engineering in NH₂-MIL-125(Ti)/copper chlorophyllin S-scheme enabling spatially...

Interfacial electronic coupling critically determines the performance of S-scheme photocatalysts, yet spatial mismatching between anchoring sites and charge-accumulation regions often limits charge transfer efficiency. Herein, a bonding-site-locked interfacial engineering strategy is proposed to construct an S-scheme heterojunction between NH₂-MIL-125(Ti) and sodium copper chlorophyllin (SCC), enabling spatially matched charge transfer pathways through ester linkages between Ti-OH and -COOH groups. The ester-linked composite (eNS) achieves a CO generation rate of 90.6 μmol g^-1 h^-1, which is 1.65 times higher than that of the amide-linked counterpart (aNS) and maintains over 80% activity after seven cycles under AM 1.5 G illumination without sacrificial agents. Comprehensive characterization and theoretical calculations reveal that ester linkage precisely anchors SCC at the Ti-OH electron-rich region, facilitating vectorial electron migration and enhancing CO₂ adsorption/activation, whereas the non-site-specific amide linkage in aNS leads to inefficient charge transfer. This study highlights bonding-site-locked interfacial design as a general route to optimize spatial charge transfer and photocatalytic efficiency in MOF-organic hybrid systems.