Shu Wang,Yongxin Jiao,Du Peng,Wenlong Yang,Hui Zhang,Shuang Han
There is growing interest in developing artificial-photosynthesized S-scheme heterostructures in photocatalytic applications. Herein, we proposed a Zn 0.5 Cd 0.5 S/WO 3 S-scheme heterostructure, possessing the trifunctionally catalytic applications of H 2 production in water-splitting, heavy metal photoreduction degradation, and antibiotic photooxidation degradation. We have chosen the optimized component to construct this heterostructure according to the best catalytic performance of Zn 1-x Cd x S solid solutions. These heterojunction composites have been prepared by traditional two-step hydrothermal method, subsequently their heterojunction construction, the photophysical transfer process of photogenerated carriers, and the photocatalytic reaction mechanism have been revealed by systemically characterizations and theoretical simulation calculations. These findings provide new insight into photocatalytic function expansion and the mechanism of photocatalytic activity improvement guided by photophysical processes.
The artificial-photosynthetic semiconductor composites have attracted tremendous attention with respect to their enhanced photocatalytic properties. Herein, we reported the facile synthesis of Zn 0.5 Cd 0.5 S/WO 3 ·H 2 O S-scheme photocatalyst via one-pot in situ hydrothermal strategy. Density Functional Theory (DFT) calculation was employed to reveal the S-scheme photogenerated electron transfer mechanism, and the subsequent experimental characterization further illustrated the path for electron-hole transfer and separation under the effect of S-scheme heterojunction. The mass of WO 3 ·H 2 O accounted for Zn 0.5 Cd 0.5 S/WO 3 ·H 2 O 48 wt% (ZCSW48) was the best high-efficiency S-scheme photocatalyst displayed significant photocatalytic properties on pollution degradation, in detail, with the Cr (VI) photoreduction rate of 2.27 μmol·s −1 ·g −1 cat. and the Rhodamine B (RhB) photooxidation rate of 0.38 μmol·min −1 ·g −1 cat. , respectively. The designed Zn 0.5 Cd 0.5 S/WO 3 ·H 2 O photocatalysts have integrated with the three aspects of photocatalytic efficiencies including the visible light response, prolonged photogenerated carrier lifetime and the sufficient surface active sites due to amount of surface defects , therefore, this work provides more insights into the utilization of green energy for environmental treatment by artificial structured semiconductors.
In our work, Zn 0.5 Cd 0.5 S/WO 3 (ZCSW) S-scheme heterostructure composites were prepared by an innovation synthesis called electrostatic adsorption method, which supported to form high-quality hetero-interface connection to efficiently improve the photocatalytic activity . Specially, 1D Zn 0.5 Cd 0.5 S (ZCS) nanorods and 2D WO 3 nanosheets were used to construct the S-scheme photocatalysts that have fully reflected both two components’ structural and morphological features. By DFT calculation, this S-scheme photogenerated electron transfer channel could be predicted by the work function between Zn 0.5 Cd 0.5 S (4.132 eV relative to vacuum level) and WO 3 (5.175 eV), thus the practical effect of the S-scheme heterojunction could support the electron flow from the valence band of Zn 0.5 Cd 0.5 S to the conduction band of WO 3 under the built-in electric field in the space charge region. Meanwhile, PL spectra and electrochemical measurement together reveal the photogenerated electron separation enhancement of ZCSW composites. For photocatalysis , ZCSW40 (40 stands for the weight ratio of WO 3 versus Zn 0.5 Cd 0.5 S) was the best catalyst among the as-prepared samples with the Cr (VI) degradation rate of 20.4 μmol min −1 ·g −1 cat. , which was nearly 3 times and 2 times higher than those of bare ZCS and the rest of ZCSW photocatalysts under the simulated solar-driven irradiation. Furthermore, ZCSW40 possessed excellent cycling stability in photocatalytic reaction, as well as the highest reaction dynamic constant of 0.92103.
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