Structure regulation of ZnS@g-C3N4/TiO2 nanospheres for efficient photocatalytic H2 production under visible-light irradiation

Abstract

High-quality mesoporous or hollow ZnS@g-C3N4/TiO2 nanospheres were fabricated successfully via structure regulation strategy for efficient photocatalytic H2 production under visible-light irradiation. The entire process was started with the construction of solid ZnS@g-C3N4/TiO2 (S-ZnS@g-C3N4/TiO2) nanospheres. Then, via TiO2 nanosheets (NSs) in situ growth or Ostwald ripening treatment, S-ZnS@g-C3N4/TiO2 could be converted into mesoporous or hollow ZnS@g-C3N4/TiO2 nanospheres automatically. The obtained porous ZnS@g-C3N4/TiO2 nanospheres were featured of regular shape, high porosity, large specific surface area and adjustable g-C3N4 content. In mesoporous ZnS@g-C3N4/TiO2 (M-ZnS-g-C3N4/TiO2) nanospheres, the specially constructed mesoporous served as channels for the access of reactants in heterogeneous catalysis. Besides, the electron-sink function of ZnS NPs and C–SOx–C sulfone bridges between ZnS and g-C3N4 could improve visible-light H2 production of M-ZnS-g-C3N4/TiO2 significantly. Additionally, the prepared hollow ZnS@g-C3N4/TiO2 (H-ZnS@g-C3N4/TiO2) nanospheres showed a lower photocatalytic H2 production than M-ZnS-g-C3N4/TiO2 due to the decreased specific surface area. Compared with traditional g-C3N4 wrapping method, the proposed structure regulation strategy is simple, effective and structural controllable. Finally, a possible photocatalytic mechanism for visible-light H2 production by porous ZnS@g-C3N4/TiO2 nanospheres was tentatively proposed.