Conjugated polyene-functionalized graphitic carbon nitride with enhanced photocatalytic water-splitting efficiency

Photoactivity of graphitic carbon nitride (g-C3N4) is seriously restricted by high recombination rate of photoinduced charge carriers. Herein, a g-C3N4/conjugated polyene (CP) complex is synthesized for the first time via a simple low-temperature calcination process. Lower photoluminescence intensity, longer fluorescence lifetimes, and higher photocurrent density of this complex than those of pure g-C3N4 indicate that CP works effectively as electron acceptors and quickly shuttles electrons through its high conductive network to decrease the recombination rate of photogenerated electrons and holes of g-C3N4 and improve the photocatalytic hydrogen production rate from 810 to 1270 mmol/g/h under visible light irradiation. The complex prepared by calcination at 340 degrees C exhibits better photoactivity than those at 240 and 400 degrees C. Hydrogen bonds between g-C3N4 and CP not only help to transfer electrons, but also fix CP molecules firmly on the surfaces of g-C3N4. This complex shows an excellent physicochemical stability in the photocatalytic process as well. This work provides not only a novel cost-effective way towards the preparation of new efficient g-C3N4-based complexes with better photoactivity, but also a new modification route to other photocatalysts for enhanced photocatalytic hydrogen production. (C) 2017 Elsevier Ltd. All rights reserved.