In situ construction of S-scheme heterojunctions between BiOCl and Bi-MOF for enhanced photocatalytic CO2 reduction and pollutant degradation

Abstract

Recently, photocatalytic technology has been widely used as a sustainable method to address environmental pollution issues. Herein, BiOCl/Bi-MOF (BOC/Bi-MOF) based semiconductor photocatalysts with S-scheme heterojunction were fabricated by an in situ growth method, and the photocatalytic activity of the materials was explored for CO₂ reduction and pollutant degradation. As confirmed by density functional theory calculations and physiochemical characterizations, the established S-scheme heterojunction confers enhanced carrier separation efficiency and retention of redox capability to the BOC/Bi-MOF. Through an improved combination of charge separation and surface reactions, the prepared BOC/Bi-MOF efficiently reduces CO₂ solely to CO. The heterojunction as catalyst is more durable and effective than any of its single component. The CO evolution rate of the optimized composite catalyst was 7.66 and 33.10 times of those of BiOCl and Bi-MOF, respectively. In addition, BOC/Bi-MOF exhibits a high efficiency in the photocatalytic degradation of the pollutant rhodamine B (RhB) in aqueous environments, and the pollutant was completely removed within 20 min. Due to the generation of interfacial potential differences, the internal electric field (IEF) generation at heterogeneous interfaces facilitates the separation and transfer of photogenic charges. This work demonstrated a practical and effective route for in situ growth of S-scheme heterojunctions with high efficiencies in CO₂ reduction and RhB degradation.