Design of a 2D/1D Bi2MoO6/Bi19S27Br3 direct Z-scheme heterojunction with a built-in internal electric field for enhanced photocatalytic CO2 reduction performance

Abstract

Bi-based heterojunctions have garnered extensive attention for photocatalytic carbon dioxide (CO₂) reduction due to their efficient charge separation and strong redox ability. The built-in internal electric field (IEF) at the interface of a direct Z-scheme heterojunction interface serves as the driving force for charge transfer; however, suboptimal interfacial contact often restricts carrier migration efficiency. Herein, we meticulously tune the contact interface over a Bi-based heterojunction by modulating the morphologies of the semiconductor components. Specifically, we synthesize a 2D/1D Bi₂MoO₆/Bi₁₉S₂₇Br₃ (BMO/BSBr) direct Z-scheme heterostructure by embedding 1D BSBr nanorods onto 2D BMO nanosheets. Such a contact interface can optimize photogenerated charge carrier migration between BMO and BSBr, thereby significantly promoting their separation. As a result, the photocatalytic CO₂ conversion performance of the optimized BMO/BSBr reaches 34.4 μmol g⁻¹ h⁻¹, exceeding those of BMO and BSBr by 4.5- and 19.8-fold, respectively. The mechanisms underlying this enhanced photocatalytic performance are revealed via in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), X-ray photoelectron spectroscopy and radical trapping tests, showing that the internal electric field along with the fine-tuned contact interface holds the key to significantly boosting photogenerated charge carrier utilization efficiency. This study provides a novel design strategy for constructing high-performance photocatalysts via interfacial chemical bonding, offering efficient charge transfer and high catalytic activity.