Breaking Type-I heterojunction limitations: Harnessing an Ohmic-like/S-scheme cascade charge transfer mechanism for enhanced photocatalytic H2 evolution

• Published in: Separation and purification technology Vol. 354; p. 129444
• Main Authors: Li, Jiangshan, Zhang, Xiao, Xiong, Xianqiang, Wu, Chenglin, Jin, Yanxian, Lv, Kangle
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 19.02.2025
• Subjects: Ohmic-like junction; S-scheme heterojunction; Type-I photocatalyst; ZnIn2S4@Bi2S3@CuCo2S4; ZnIn2S4@Bi2S3@CuCo2S4; Type-I photocatalyst; Ohmic-like junction; S-scheme heterojunction
• ISSN: 1383-5866
• DOI: 10.1016/j.seppur.2024.129444

[Display omitted] •This study presents a new ZIS@Bi@Cu heterostructure overcoming traditional Type-I photocatalytic inefficiencies.•A unique “Ohmic-like/S-scheme” charge transfer mechanism is proposed.•The ternary ZIS@Bi@Cu photocatalysts exhibit higher activity and stability than ZIS.•This research offers insights into developing efficient photocatalysts despite ZIS@Bi’s Type-I characteristics. 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.