Atomically
precise metal nanoclusters (NCs) demonstrate emerging
potential as a new generation of photosensitizers in photoredox catalysis.
However, metal NCs suffer from intrinsic poor instability, which leads
to the loss of photosensitization effect and hampers their widespread
applications in heterogeneous photocatalysis. Herein, we corroborate
the design of a spatially directional charge transfer pathway over
transition metal chalcogenide (TMC)-based heterostructures by way
of a facile and efficient electrostatic self-assembly approach. Positively
charged solid-state nonconjugated insulating polymer of poly(allylamine
hydrochloride) (PAH) and negatively charged glutathione (GSH) capped
metal NCs [Ag9@(GSH)6] as building blocks were
controllably and highly ordered anchored on the TMC substrate. It
was unveiled that owing to the appropriate energy level alignment
and interface configuration, photogenerated electrons over metal NCs
can directionally flow to the TMC substrate with the aid of PAH, which
functions as an interfacial charge transfer mediator, and simultaneously
holes migrate in the opposite direction, thereby collaboratively contributing
to substantially boosted charge separation and prolonged charge lifetime.
Benefiting from these merits, the thus self-assembled TMCs/PAH/metal
NC heterostructure unfolds conspicuously enhanced photoactivity toward
anaerobic selective photocatalytic reduction of nitroaromatics to
amino derivatives under visible light irradiation. This work would
significantly reinforce our fundamental understanding of the charge
transfer characteristic of atomically precise metal NCs and the charge-withdrawing
capability of solid insulating polymers for solar energy conversion.