A highly efficient visible-light responsive sprayed WO3/FTO photoanode for photoelectrocatalytic degradation of brilliant blue

Surface-oxygen vacancy defect-promoted electron-hole separation of defective tungsten trioxide ultrathin nanosheets and their enhanced solar-driven photocatalytic performance

Defective WO₃ ultrathin surface-engineered nanosheets are fabricated by a solvothermal and low-temperature surface hydrogenation reduction strategy. The obtained defective WO₃ ultrathin nanosheets with thicknesses of ∼4 nm possess a relatively large surface area of ∼25 m² g^-1. After surface engineering, the bandgap is narrowed to ∼2.48 eV due to the presence of surface oxygen vacancies, which further enhance the visible light absorption. The defective WO₃ ultrathin nanosheets exhibit excellent solar-driven photocatalytic degradation performance for the complete degradation of the highly-toxic metribuzin herbicide (∼100%). The first-order rate constant (k) of the defective WO₃ ultrathin nanosheets is ∼3 times higher than that of the pristine one. This can be ascribed to the formation of suitable surface-oxygen vacancy defects that promote the separation of photogenerated electron-hole pairs, and the two-dimensional ultrathin structure facilitating the surface engineering as well as furnishing a large number of surface active sites. Moreover, the defective WO₃ ultrathin nanosheets exhibit high stability because the photocatalytic activity remains almost unchanged after 10 cycles, making them favorable for practical applications. This work offers new insights into the fabrication of other high-performance ultrathin nanosheet oxide photocatalysts for environmental applications.

A novel visible-light responsive photocatalytic fuel cell with a heterostructured BiVO4/WO3 photoanode and a Pt/C air-breathing cathode

A series of heterostructured BiVO₄/WO₃ photoanodes were successfully prepared via a two-step method of hydrothermal deposition and impregnation. The optimized BiVO₄/WO₃ sample showed the highest photocurrent density of ∼880 μA/cm² at 0.8 V (vs Ag/AgCl) in 0.1 M KH₂PO₄ aqueous solution (pH 7) under simulated AM1.5 illumination. The optimized BiVO₄/WO₃ photoanode was coupled with a Pt/C air-breathing cathode to build up a visible-light responsive PFC system. The as-prepared PFC system showed outstanding photoelectrocatalytic performances in converting organics into electricity, and when glucose was used as the 'fuel', the maximum power density (P_max) and the short-circuit current density (I_sc) were 8.58 μW/cm² and 91.8 μA/cm², respectively. Degradation experiments showed that the removal rate of tetracycline hydrochloride in PFC with BiVO₄/WO₃ photoanode and Pt/C air-breathing cathode was ∼87.2% in 8 h, which was much higher than photolysis and photocatalysis process. The mechanism responsible for the enhanced photoelectrocatalytic performance of the as-prepared PFC system was also discussed.

Ultrasound assisted synthesis of WO3-ZnO nanocomposites for brilliant blue dye degradation

The present work deals with the preparation of WO₃ and WO₃-ZnO nanocomposites in presence of ultrasonic irradiation, and its use in the sonocatalytic degradation of brilliant blue dye. WO₃-ZnO nanocomposite is prepared using one step in-situ ultrasound assisted method. The successfully prepared WO₃ and WO₃-ZnO nanocomposites were characterized using different characterization techniques such as XRD, Raman, BET, FE-SEM and EDS. The XRD pattern reveals that the formation of monoclinic and hexagonal crystal structures of WO₃ and ZnO respectively. BET study shows that WO₃-ZnO nanocomposite have maximum surface area than that of the WO₃. EDS study confirms the formation of WO₃-ZnO nanocomposites. Further the use of the prepared WO₃ and WO₃-ZnO nanocomposites as a sonocatalyst for the degradation of brilliant blue dye. The rate constant (k) was evaluated as a function of the initial concentration of brilliant blue dye. It is found that WO₃-ZnO nanocomposites exhibits maximum sonocatalytic activity as compared to WO₃ photocatalyst.