Exfoliated, mesoporous W18O49/g-C3N4 composites for efficient photocatalytic H2 evolution

Abstract

Rapid recombination of photogenerated carriers and lack of active sites have always been the problems for enhancing the H2 evolution performance of semiconductor-based photocatalysts, which can be solved promisingly by co-catalysis and lifting specific surface area, respectively. In this work, a simple two-step green route is developed to synthesize novel exfoliated and mesoporous W18O49/g-C3N4 composites through calcining the precursors of g-C3N4 powder impregnated with ammonium tungstate solution in a reductive atmosphere produced by the pyrolysis of polyacrylonitrile powder. With the optimal loading amount of W18O49, the obtained W18O49/g-C3N4 composite presents an excellent photocatalytic performance for H2 production in triethanolamine aqueous solution under visible light. The H2 evolution rate at 7 °C was 912.3 μmol⋅g−1h−1, 9.7-fold higher than that of pure g-C3N4. In addition, the mechanism of the H2 production over the obtained W18O49/g-C3N4 photocatalysts was also proposed. This work will provide a new strategy for improving the specific surface area of nanomaterials and constructing the heterojunctions between different nanostructures simultaneously.