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

A hydrogen-bonded hybrid photocatalyst composed of graphitic carbon nitride (g-CN) and a boron-functionalized polymer has been developed to achieve efficient solar-driven hydrogen evolution. The heterostructure not only enhances light harvesting but also facilitates charge transfer. Using a platinum cocatalyst and triethanolamine as a sacrificial agent further boosts the overall photocatalytic performance, demonstrating synergistic effects for visible-light-driven hydrogen production.

To generate hydrogen efficiently by using visible light, it is important to investigate closely contacted halogens (Cl, Br, I)-conjugated polymer semiconductors/g-C₃N₅ heterojunction photocatalysts with photogenerated-carrier separation. This work demonstrated the successful fabrication of halogens (Cl, Br, I)-conjugated poly [3-thienylboronic acid (BA)]/g-C₃N₅ 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-C₃N₅ to IBA. To maintain tight interface contacts, boronic acid groups [–B(OH)₂] of (Cl, Br, I) poly-BA and amino groups (–NH₂) of g-C₃N₅ exhibit hydrogen bonding interactions. When comparing the ratio-optimized 5IBA–CN to g-CN, it demonstrates a 34-fold improvement in hydrogen (H₂) 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.

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