All-solid-state Z-scheme WO3/HTiNbO5-NS heterojunctions with enhanced photocatalytic performance

A novel Z-scheme WO3/HTiNbO5-NS heterojunction photocatalysts were prepared by a facile hydrothermal method. The crystalline structures, microstructures, photoelectrochemical properties and compositions of the as prepared samples were characterized in detail. Furthermore, the photocatalytic activities of the as-prepared samples were evaluated for the photodegradation of Rhodamine B solution under simulated sunlight irradiation. The photocatalytic results showed that the WO3/HTiNbO5-NS photocatalysts exhibit superior photocatalytic activity for the degradation of RhB as compared with pristine WO3 and HTiNbO5-NS. Among the photocatalysts with different mass percentages, the 10%-WO3/HTiNbO5-NS (denoted as 10-WO/HNTS) photocatalyst achieved the highest photocatalytic activity for photodegradation of RhB solution. The enhanced photocatalytic performance could be well explained by the formation of direct Z-scheme WO3/HTiNbO5-NS heterojunctions that can not only promote the separation of photo-induced electrons and holes, but also keep high redox potential. The UV-vis absorption spectra indicated that the loading of WO3 can enhance the absorption of visible light. The decreased PL intensities, the increased photocurrent intensities, and the decreased impedance all suggested that the separation rate of photo-generated electrons and holes was highly enhanced. Finally, the possible direct Z-scheme photocatalytic mechanism was also proposed.