WO_3–x/PbS/Au Ternary Heterojunction Nanostructures for Visible-Light-Driven Photocatalytic Hydrogen Generation

The design of photocatalyst with excellent light-harvesting and charge-separation abilities is quite important for high-performance photocatalysis. Herein, narrow-bandgap PbS, wide-bandgap WO3–x, and Au nanoparticles were combined to form a plasmon-mediated Z-scheme nanostructure for the first time. Particularly, PbS nanoparticles were deposited on oxygen-abundant WO3–x nanobricks, then Au nanoparticles were grown on the hybrids to form WO3–x/PbS/Au ternary nanostructures. Because of the cooperation of wide and narrow bandgaps as well as the oxygen vacancies and plasmon, the ternary hybrids displayed wide light absorption ranging from ultraviolet to near-infrared region. Meanwhile, the energy band arrangement of PbS and WO3–x provides a direct Z-scheme pathway and built-in electric field for charge transfer and separation. As a result, WO3–x/PbS hybrids displayed a large enhancement on photocatalytic hydrogen generation activity compared with the components under visible light irradiation, which is 9.2 and 9.8 times of WO3–x and PbS, respectively. Furthermore, the WO3–x/PbS/Au ternary hybrids showed the best photocatalytic performance that is 21.8 and 2.4 times of WO3–x and WO3–x/PbS hybrids. Meanwhile, the ternary photocatalysts possessed prominent apparent quantum efficiency under near-infrared light irradiation. The prominent photocatalytic performance can be attributed to the broadband light absorption, enhanced specific surface area, efficient charge transfer and separation induced by the oxygen-vacancy and plasmon-mediated Z-scheme band energy structure.