Gun-Bullet Model-Based Noncovalent Interactions Boosting Visible Light Photocatalytic Hydrogen Production in Poly Thieno[3,2-b]Thiophene/Graphitic Carbon Nitride Heterojunctions.

Linear conjugated polymer photocatalysts are still hampered by challenges involving low charge separation efficiency and poor water dispersibility, which are crucial factors during the photocatalytic water splitting process. Herein, we synthesized Poly thieno[3,2-b]thiophene (PTT) nanoparticles with excellent visible light response characteristic. Subsequently, we constructed the gun-bullet model PTT/graphitic carbon nitride (PTT/g-C₃N₄) heterojunctions for photocatalytic hydrogen production, where PTT with good visible light response characteristic serves as the bullets and g-C₃N₄ with good water dispersibility serves as the guns. The as-prepared PTT/g-C₃N₄ heterojunctions show greatly accelerated charge separation and excellent photocatalytic hydrogen production performance. Specifically, 10PTT/g-C₃N₄ demonstrates extraordinary hydrogen production performance, reaching 6.56 mmol g^-1 h^-1 (2 wt% Pt loading, 0.1 M AA as sacrificial agent, λ > 420 nm), calculated to be 15.3 and 22.6 times those of PTT and g-C₃N₄, respectively. Mechanistic studies reveal that the significantly improved performance of PTT/g-C₃N₄ heterojunctions is ascribed to the accelerated charge transfer, which originates from the C…S/N…S noncovalent interactions among PTT and g-C₃N₄. The C…S/N…S noncovalent interactions act as an efficient interface charge transmission channel (ICTC), accelerating the steady stream of excited electron transfer from the lowest unoccupied molecular orbital (LUMO) of PTT to that of g-C₃N₄. The gun-bullet model heterojunctions proposed here provide a practical strategy for achieving exceptional visible light photocatalytic hydrogen production by combining charge separation with water dispersibility in polymer/polymer heterojunctions via noncovalent interactions.