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

Abstract

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 WS /graphitic carbon nitride (CN) 2D/2D nanosheet heterostructure decorated with CdS quantum dots (QDs) has been designed, for the first time. Optimized CdS/WS /CN without another cocatalyst exhibits a significantly enhanced photocatalytic H evolution rate of 1174.5 μmol h g 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/WS /CN photocatalyst shows excellent stability and reusability without apparent decay in the photocatalytic H 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.

Fabrication of interlayer β-CD/g-C3N4@MoS2 for highly enhanced photodegradation of glyphosate under simulated sunlight irradiation

“…10,11,21 As shown in Fig. 3c, deconvolution of the N 1s spectrum revealed four peaks at 404.2, 401.6, 399.7 and 398.8 eV, which correspond to charging effects and C-NH, N-(C) 3 and C-N]C bonds, respectively, which is consistent with reports by Zou et al and Ran et al 22,23 In particular, two peaks centered at 532.9 and 531.8 eV were detected in the spectra of O-C 3 N 4 and O-C 3 N 4 /MoS 2 -5, which were due to O-C]O and C-O groups. Moreover, the C/N ratio increased from 0.460 in g-C 3 N 4 to 0.503 in O-C 3 N 4 /MoS 2 -5, which led to nitrogen vacancies.…”

Facile synthesis of MoS 2 QDs/TiO 2 nanosheets via a self‐assembly strategy for enhanced photocatalytic hydrogen production

“…Generally, the separation and transfer of photo‐excited electron‐hole pairs and surface redox reactions are the most critical steps in heterogeneous photocatalytic reaction, which decides whether these photocatalysts can reach to high quantum efficiency . For the sake of addressing this problem, a great amount of effort has devoted to coupling cocatalyst on the surface of semiconductor, which can decrease the activation barriers and provide more active sites to enhance the photocatalytic activity . Therefore, it is important to seek a suitable and low‐cost cocatalyst for improving the solar conversion efficiency of semiconductor photocatalyst.…”

“…21,22 For the sake of addressing this problem, a great amount of effort has devoted to coupling cocatalyst on the surface of semiconductor, which can decrease the activation barriers and provide more active sites to enhance the photocatalytic activity. [23][24][25][26] Therefore, it is important to seek a suitable and low-cost cocatalyst for improving the solar conversion efficiency of semiconductor photocatalyst.Recently, molybdenum disulfide (MoS 2 ) as a costeffective cocatalyst to take place of precious metals has received considerable attention for hydrogen evolution…”

Recent progress of tungsten- and molybdenum-based semiconductor materials for solar-hydrogen production

“…14d). Similarly, MoSe 2 [254][255][256], WS 2 [257][258][259], and WSe 2 [260] can also be used as HER cocatalysts for solar-hydrogen production.…”