Enhancing Cs₂AgBiBr₆ Photocatalysis via Rationalizing S-Scheme Heterojunction with Zinc Phthalocyanine as the...

Area of Science:

• Materials Science
• Photocatalysis
• Environmental Chemistry

Background:

• Lead-free double perovskite Cs₂AgBiBr₆ (CABB) shows photocatalytic potential but suffers from electron-hole recombination and limited active sites.
• Zinc phthalocyanine (ZnPc) can act as an electron reduction site, beneficial for photocatalytic processes.

Purpose of the Study:

• To construct an S-scheme heterojunction photocatalyst by integrating CABB nanosheets with a ZnPc substrate.
• To enhance the photocatalytic efficiency of CABB by improving charge separation and transfer through heterojunction formation.

Main Methods:

• In situ growth of CABB nanosheets on a ZnPc substrate.
• Comprehensive characterization techniques to confirm interfacial bonding (Zn-Br) and heterojunction formation.
• Photocatalytic degradation experiments using Rhodamine B (RhB) under visible light, supported by photoelectrochemical measurements and density functional theory (DFT) calculations.

Main Results:

• Formation of robust interfacial Zn-Br bonds between ZnPc and CABB, ensuring intimate contact.
• The optimized 0.05ZnPc/CABB composite demonstrated significantly enhanced photocatalytic activity, degrading RhB completely in 20 min.
• S-scheme band alignment, facilitated by Zn-Br bonds and a built-in electric field, improved charge separation and transfer.
• The composite exhibited excellent stability, retaining 99% degradation efficiency after five cycles.

Conclusions:

• The constructed S-scheme heterojunction effectively addresses the limitations of pristine CABB, leading to superior photocatalytic performance.
• The ZnPc/CABB composite presents a novel and stable strategy for efficient environmental remediation applications.
• This work highlights the potential of S-scheme heterojunctions for advancing lead-free perovskite photocatalysts.