Abstract
Type-I band alignment is typically associated with poor photocatalytic efficiency, attributed to inadequate charge separation and diminished redox potential of photoexcited e-/h+. Herein, we propose a novel ternary ZnIn2S4@Bi2S3@CuCo2S4 heterostructure that challenges the current paradigm by showing enhanced photocatalytic performance, despite exhibiting the traditional Type-I straddled band alignment in the ZnIn2S4@Bi2S3 region. The enhancement in activity is attributed to the Fermi level variation causing different energy band bending, thereby leading to an Ohmic-like charge transfer at the ZnIn2S4@Bi2S3 interface and an S-scheme charge transfer at the Bi2S3@CuCo2S4 interface. The Ohmic-like/S-scheme charge transfer mechanism overcomes the inherent limitations of the Type-I heterojunction through efficient separation of photogenerated charge carriers and preservation of their high reduction potential of electrons. Owing to these factors, an optimal composition featuring 2.5 wt% CuCo2S4 in ZnIn2S4@Bi2S3@CuCo2S4 exhibits the highest H2 evolution rate of 8.1 mmol g-1h−1, which is 9.3 times greater than that of pure ZnIn2S4. This study highlights the potential for achieving improved photo-activity using a Type-I-like composite, thus broadening the prospects for subsequent research in the pertinent field.
Published Version
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