Optimal synthesis of a direct Z-scheme photocatalyst with ultrathin W18O49 nanowires on g-C3N4 nanosheets for solar-driven oxidation reactions

Constructing Z-scheme photocatalysts is an effective approach to enhance the conversion efficiency of solar to chemical energy. Herein, W 18 O 49 /g-C 3 N 4 heterostructures have been synthesized by growing W 18 O 49 ultrathin nanowires on g-C 3 N 4 nanosheets via a convenient solvothermal process. Various characterizations were performed on the materials to understand the structure-performance relationship. The photocatalytic properties of the W 18 O 49 /g-C 3 N 4 heterostructures were evaluated by the two oxidation reactions, phenol degradation and oxidative N C coupling of benzylamines , under a simulated sunlight (360 ≤  λ  ≤ 780 nm). With tuning the W 18 O 49 /g-C 3 N 4 mass ratio, the optimal photocatalyst of W 18 O 49 (30)/g-C 3 N 4 containing 30 wt% W 18 O 49 nanowires exhibited the highest activity in both the photocatalytic reactions. The generations and contributions of the active species in the photocatalytic reactions were identified by electron spin resonance (ESR) spectra and active-species-eliminating experiments. Accordingly, the photocatalytic mechanism of W 18 O 49 /g-C 3 N 4 heterostructures has been expounded based on the direct Z-scheme electron transfer between the two semiconductors as well as the synergistic actions of active sites on W 18 O 49 nanowires and g-C 3 N 4 nanosheets . This work demonstrates a rational paradigm to construct 1D/2D semiconductor heterostructures and provides further insights into Z-scheme photocatalytic mechanism for boosting solar-driven pollutant degradation and organic transformation.