Min Zhang,Yunyuan Dong,Mengling Peng,Xiaobin Chen,Qifu Zheng,Jianming Liao,Wei Chen
Construction of carbon-based heterostructural photocatalyst materials with high electron transfer rates is a practical and effective strategy for the mineralization of organic pollutants and removal of toxic metal ions under visible-light irradiation. This study developed a facile hydrothermal route to prepare a series of heterojunction photocatalysts, wherein Zn x Cd 1- x In 2 S 4 nanosheets were immobilized on nitrogen and phosphorus co-doped hollow carbon spheres (N, P-C) to form N, P-C@Zn x Cd 1- x In 2 S 4 nanocomposites. Comprehensive characterization of the nanocomposites revealed that the tuning of the Zn/Cd molar ratio could effectively modulate the Zn x Cd 1− x In 2 S 4 energy band structure. Moreover, Zn 0.5 Cd 0.5 In 2 S 4 had the most negative conduction band position and loads on non-metal-doped carbon, with superior carrier transport properties and separation efficiency. N, P-C@Zn 0.5 Cd 0.5 In 2 S 4 (N, P-C@ZCIS2) exhibited the best photocatalytic activity for tetracycline hydrochloride degradation and Cr(VI) reduction, with rate constants of 0.04822 mg −1 min −1 and 0.14303 min −1 , respectively. Notably, the photocatalysts exhibited good activity and stability even after cycle experiment. This study provides new insights into the design of carbon-based heterojunction photocatalysts for the removal of harmful chemicals.
The design of energy band structures and the construction of composite materials are effective ways to improve photocatalytic activity. Hence, Zn x Cd 1−x In 2 S 4 /MoS 2 composites were first prepared in this work by combining Zn x Cd 1−x In 2 S 4 solid solution and MoS 2 nanosheets. The solid solution strategy partly avoided the potential conflicts between visible-light absorption and redox capacity through energy band modulation, and MoS 2 provided more active sites and facilitated the separation of photogenerated carriers. This reasonable structural design improved the visible-light absorption capacity, achieved the appropriate redox potential, promoted carrier separation and transfer during photocatalysis. As-prepared composites of Zn 1/2 Cd 1/2 In 2 S 4 /MoS 2 -18.9% showed excellent photocatalytic hydrogen evolution performance under visible-light illumination, which provided a hydrogen evolution rate of 2255.21 μmol g −1 h −1 with an quantum yield of 19.55% under incident monochromatic light of 420 nm. Zn 1/2 Cd 1/2 In 2 S 4 /MoS 2 composites also displayed long-term stability after five photocatalytic cycles. Finally, the relevant photogenerated charge transfer and catalytic mechanisms of Zn x Cd 1−x In 2 S 4 and Zn 1/2 Cd 1/2 In 2 S 4 /MoS 2 composites were proposed and analyzed.
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