In situ construction of S-scheme heterojunction-conjugated polymer/g-C3N4 photocatalysts for enhanced H2 production and organic pollutant degradation

Herein, we report the synthesis of poly[(pyrene-1,3,6,8-yl)-phenyl-1,4-yl)-tri-phen] (PPyPP) loaded g-C3N4 nanocomposites by one-step in situ thermal condensation of 1,4-phenylenebiboronic acid, 1,3,6,8-tetrabromopyrene, 1,3,5-tribromobenzene and g-C3N4 by Suzuki reaction. The composites are characterized by FTIR, SEM, UV-vis, FL and EIS. PPyPP/g-C3N4 composites demonstrate a significantly improved H-2 evolution rate (HER) and degradation of neutral red (NR) compared to pure g-C3N4. An optimal HER of 28.2 mol h(-1)(without Pt) and the NR degradation rate of 0.739 min(-1) are demonstrated by PPyPP/g-C3N4-0.2 composite under visible light irradiation. It is noteworthy that this HER is 42 times higher and the NR degradation rate is 30 times higher than that of pure g-C3N4, which can be attributed to the formation of a polymer heterojunction and effective charge transfer between PPyPP and g-C3N4. Another reason is that there are more electrons and holes involved in the reaction because of the S-scheme.