Superposition of bulk and interface electric field for boosting charge transfer in Bi2MoO6/Bi19Br3S27 S-scheme heterojunctions

Abstract

Coupling bulk and interface electric field for enhancing photogenerated charge carrier separation represents an effective strategy toward enhancing photocatalytic performance due to the potential of superposition of electric field. However, the detailed mechanism of synergistic effect of the bulk and interface electric field in facilitating photogenerated charge carrier remains underexplored, limiting its wide applications. Herein, we integrate the bulk electric field of Bi₂MoO₆ (BMO) with interface electric field (IEF) of S-scheme heterojunction formed between BMO and Bi₁₉Br₃S₂₇ (BBS) for enhancing photocatalytic performance. The two electric fields can not only superimpose for amplifying electric field strengths, but also act as the funnel for guiding photogenerated charge carrier migration towards specific regions for redox reactions. Moreover, the Mo–S bonds formed between BMO and BBS act as a channel for charge transfer, accelerating the charge transfer of the S-scheme and achieving effective charge separation. As a proof-of-concept, we employ optimized BMO/BBS S-scheme heterojunction for photocatalytic CO₂ conversion, reaching about 32.4 times and 2.0 times to that of pristine BMO and unmodulated BMO/BBS for CO production. This method of promoting the IEF by coupling bulk and interface electric field provides new insights into the construction of S-scheme heterojunctions for photocatalysis.