Exploring Halogenation and Hydrogen Bonding in Conjugated Poly (3‐Thienylboronic Acid)/g‐C₃N₅ Nanosheet Heterojunctions for Highly Efficient Photocatalytic Hydrogen Production Under Visible Light Irradiation

To generate hydrogen efficiently by using visible light, it is important to investigate closely contacted halogens (Cl, Br, I)‐conjugated polymer semiconductors/g‐C 3 N 5 heterojunction photocatalysts with photogenerated‐carrier separation. This work demonstrated the successful fabrication of halogens (Cl, Br, I)‐conjugated poly [3‐thienylboronic acid (BA)]/g‐C 3 N 5 nanosheet heterojunctions for hydrogen evolution utilizing visible light. Photoluminescence spectra (PL), time‐resolved photoluminescence spectra, and density functional theory suggest that the improved photocatalytic performance results from charge separation generated by photo‐generated electron transfer from g‐C 3 N 5 to IBA. To maintain tight interface contacts, boronic acid groups [–B(OH) 2 ] of (Cl, Br, I) poly‐BA and amino groups (–NH 2 ) of g‐C 3 N 5 exhibit hydrogen bonding interactions. When comparing the ratio‐optimized 5IBA–CN to g‐CN, it demonstrates a 34‐fold improvement in hydrogen (H 2 ) production activity up to 4107.5 μmol g h −1 during visible‐light radiation exposure. An abundant hydrogen bonding network on the surfaces of heterojunctions facilitates the uniform layering of Pt nanoparticles as cocatalysts. This research persents a feasible method for designing heterojunctions from polymeric materials to be used as solar‐light‐driven photocatalysts.