Bridging regulation in graphitic carbon nitride for band-structure modulation and directional charge transfer towards...

The bridging N atom in g-C₃N₄ structure plays a decisive role in photo-generated charge transfer because it usually confines photo-generated electrons and holes in each heptazine, thus leading to severe recombination. In this work, a kind of 2-aminoterephthalic acid-derived benzene ring group with rich π-electrons was considered to integrate with bridging N to break the above-mentioned confining effect. On the basis of density-functional theory calculations and experimental analysis, this 2-aminoterephthalic acid-derived bridging structure facilitated to draw photo-generated charge out of heptazine unit, and its polarized asymmetric structure promoted the directional transfer of photo-generated charge carriers across adjacent heptazines, thus efficiently reducing the recombination. Meanwhile, the 2-aminoterephthalic acid-derived bridging structure also reinforced the connectivity of heptazine units in g-C₃N₄ framework and led to high degree of polymerization, which thus extended the π-conjugated electronic system of g-C₃N₄ and modulated the band structure favoring photocatalytic hydrogen production. Consequently, a high photocatalytic H₂-production activity of 24,595 μmol h^-1 g_cat^-1 was achieved on the bridging regulated g-C₃N₄ under visible light, with an apparent quantum yield of 48.7% at 425 nm.