Hollow Core-Shell potassium Phosphomolybdate@Cadmium Sulfide@Bismuth sulfide Z-Scheme tandem heterojunctions toward optimized Photothermal-Photocatalytic performance

A hollow core-shell potassium phosphomolybdate (KMoP)@cadmium sulfide (CdS)@bismuth sulfide (Bi2S3) Z-scheme tandem heterojunction is fabricated by a simple hydrothermal strategy and kept in a water bath to continue the reaction. At the same time, the ternary structure combined Keggin-type polyoxometalate with two photosensitive sulfide semiconductors to form a stable hollow core-shell heterojunction. KMoP@CdS@Bi2S3 with a narrow band gap of similar to 1.2 eV also has excellent photothermal performance, which may further promote photocatalytic efficiency. The hollow core-shell KMoP@CdS@Bi2S3 tandem heterojunction shows excellent H-2 production performance, Cr-VI reduction ability and photocatalytic degradation performance of highly toxic tetracycline (TC). Under visible light irradiation, the photocatalytic H-2 generation rate of the KMoP@CdS@Bi2S3 tandem heterojunction reaches 831 mu mol h(-1), which is 103 times higher than that of pristine KMoP. The photocatalytic reduction efficiency of Cr-VI and degradation efficiency of TC are as high as 95.5 and 97.51%, similar to 4 times higher than that of KMoP. The boosted photocatalytic performance can be ascribed to the formation of core-shell Z-scheme tandem heterojunctions favoring spatial charge separation and the narrow band gap, which extends the photoresponse to visible light/NIR regions. When TC and Cr-VI exist at the same time, the reduction efficiency of Cr-VI can be as high as 99.64% because the intermediate of TC degradation can promote the reduction of Cr-VI. In addition, the photocatalytic performance of the KMoP@CdS@Bi2S3 heterojunction remains nearly constant after 4 recycles, which indicates high stability. The design strategy may provide new insights for preparing other high-performance core-shell tandem heterojunction photocatalysts for solar energy conversion. (C) 2021 Elsevier Inc. All rights reserved.

Automated summary

A hollow core-shell potassium phosphomolybdate (KMoP)@cadmium sulfide (CdS)@bismuth sulfide (Bi2S3) Z-scheme tandem heterojunction with a narrow band gap and excellent photothermal performance was fabricated. This structure showed outstanding photocatalytic performance in H-2 production, Cr-VI reduction, and degradation of tetracycline (TC). The high stability and boosted photocatalytic performance were attributed to the core-shell Z-scheme tandem heterojunction design strategy.