S-scheme heterojunction/Schottky junction tandem synergistic effect promotes visible-light-driven catalytic activity

• Published in: Nano research Vol. 16; no. 2; pp. 2152 - 2162
• Main Authors: Wang, Shuai, Du, Xin, Yao, Changhao, Cai, Yifeng, Ma, Huiyuan, Jiang, Baojiang, Ma, Jun
• Format: Journal Article
• Language: English
• Published: Beijing Tsinghua University Press 01.02.2023
• Subjects: Atomic/Molecular Structure and Spectra; Biomedicine; Biotechnology; Chemistry and Materials Science; Condensed Matter Physics; Materials Science; Nanotechnology; Research Article; MXene Ti; ZnIn; S; C; quantum dots (QDs); α-Fe; step-scheme heterojunction; Schottky junction; bisphenol A; O
• ISSN: 1998-0124; 1998-0000
• DOI: 10.1007/s12274-022-4960-8

Designing photocatalysts with high light utilization and efficient photogenerated carrier separation for pollutant degradation is one of the important topics for sustainable development. In this study, hierarchical core-shell material α-Fe 2 O 3 @ZnIn 2 S 4 with a step-scheme (S-scheme) heterojunction is synthesized by in situ growth technique, and MXene Ti 3 C 2 quantum dots (QDs) are introduced to construct a double-heterojunction tandem mechanism. The photodegradation efficiency of α-Fe 2 O 3 @ZnIn 2 S 4 /Ti 3 C 2 QDs to bisphenol A is 96.1% and its reaction rate constant attained 0.02595 min −1 , which is 12.3 times that of pure α-Fe 2 O 3 . Meanwhile, a series of characterizations analyze the reasons for the enhanced photocatalytic activity, and the charge transport path of the S-scheme heterojunction/Schottky junction tandem is investigated. The construction of the S-scheme heterojunction enables the photo-generated electrons of α-Fe 2 O 3 and the holes of ZnIn 2 S 4 to transfer and combine under the action of the reverse built-in electric field. Due to the metallic conductivity of Ti 3 C 2 QDs, the photogenerated electrons of ZnIn 2 S 4 are further transferred to Ti 3 C 2 QDs to form a Schottky junction, which in turn forms a double-heterojunction tandem mechanism, showing a remarkable charge separation efficiency. This work provides a new opinion for the construction of tandem double heterojunctions to degrade harmful pollutants.