Ligand-amplified quantum tunneling in polymer-mediated artificial photosystems

Quantum tunneling offers a fascinating paradigm for orchestrating spatial charge transport in artificial photosynthesis. However, precisely manipulating electron tunneling across well-defined heterointerfaces remains a formidable challenge, with conventional designs largely confined to classical Semiconductor-Insulator-Metal (S-I-M) architectures. Herein, we report a conceptual endeavor by fundamentally departing from the traditional S-I-M model, constructing a unique and novel semiconductor-insulator-ligand/metal tunneling platform. Specifically, an ultrathin insulating poly(sodium 4-styrenesulfonate) (PSS) layer is engineered onto a transition metal chalcogenide (TMC, e.g., CdS) substrate. Subsequently, poly(diallyldimethylammonium chloride) (PDDA)-capped metal nanocrystals (M@PDDA, M = Au, Pd) are precisely anchored via electrostatic self-assembly, yielding well-defined TMC@PSS/M@PDDA heterostructures. Distinct from conventional systems, the PDDA ligands synergistically couple with the metal core to form an integrated, highly potent electron capture center driven by the Schottky-junction effect. This unique synergistic driving force triggers non-classical, directional electron tunneling from the photoexcited TMC substrate directly through the insulating PSS barrier. Benefiting from this advantageous quantum tunneling, TMC@PSS/M@PDDA heterostructures demonstrate significantly enhanced and multifarious visible-light-driven photoredox activities including selective organic transformations and H₂O₂ production. This work establishes an elegant conceptual paradigm for decoding and customizing quantum tunneling pathways, offering profound fundamental insights into advanced solar energy conversion.