WS₂ /Graphitic Carbon Nitride Heterojunction Nanosheets Decorated with CdS Quantum Dots for Photocatalytic Hydrogen...

Two-dimensional/two-dimensional (2D/2D) stacking heterostructures are highly desirable in fabricating efficient photocatalysts because face-to-face contact can provide a maximized interfacial region between the two semiconductors; this largely facilitates the migration of charge carriers. Herein, a WS₂ /graphitic carbon nitride (CN) 2D/2D nanosheet heterostructure decorated with CdS quantum dots (QDs) has been designed, for the first time. Optimized CdS/WS₂ /CN without another cocatalyst exhibits a significantly enhanced photocatalytic H₂ evolution rate of 1174.5 μmol h^-1  g^-1 under visible-light irradiation (λ>420 nm), which is nearly 67 times higher than that of the pure CN nanosheets. The improved photocatalytic activity can be primarily attributed to the highly efficient charge-transfer pathways built among the three components, which effectively accelerate the separation and transfer of photogenerated electrons and holes, and thus, inhibit their recombination. Moreover, the extended light-absorption range also contributes to excellent photocatalytic efficiency. In addition, the CdS/WS₂ /CN photocatalyst shows excellent stability and reusability without apparent decay in the photocatalytic H₂ evolution within 4 cycles in 20 h. It is believed that this work may shed light on specifically designed 2D/2D nanosheet heterostructures for more efficient visible-light-driven photocatalysts.