Multiscale Active Site Modulation in Organic Heterojunction with Molecular‐Level Interfacial Contact for Efficient Photocatalytic Hydrogen Evolution

The commercialization of green hydrogen production through organic photocatalyst‐promoted solar water splitting for hydrogen evolution is limited by inefficient charge separation and sluggish interfacial kinetics. Herein, this problem is addressed using an ice template–assisted photochemical reduction strategy that integrates molecular‐level interfacial contact between a trefoil‐shaped donor–acceptor molecule (DTAB) and ultrathin carbon nitride nanosheets (UCNS) with Cu single atoms (SAs) anchoring and Pt nanodots (NDs) deposition. The intimate interface in the resulting DTAB–UCNS/CuPt photocatalyst generates a built‐in electric field promoting the separation of photogenerated carriers. The DTAB harvests visible light and injects electrons into UCNS, with these electrons subsequently funneled to Pt NDs via Cu SAs. The electronic coupling between Cu SAs and Pt NDs affects the position of the Pt d ‐band, thus optimizing the H* adsorption/desorption equilibrium and enhancing surface reaction kinetics. The hydrogen evolution rate of DTAB–UCNS/CuPt (261.16 mmol g −1 h −1 ) is 248.7 times higher than that of UCNS/Pt (1.05 mmol g −1 h −1 ) and ranks among the highest reported for carbon nitride–based photocatalysts under comparable conditions, highlighting the strong potential of our strategy to advance photocatalytic hydrogen evolution toward practical green hydrogen production.