Pioneering SubPc-Br/CdS S-scheme heterojunctions: Achieving superior photocatalytic oxidation through enhanced radical synergy and photocorrosion mitigation

Abstract

For the efficient harnessing of solar energy and mitigation of environmental pollution, the development and application of semiconductor photocatalysis technology is paramount. Herein, a novel SubPc-Br/CdS supramolecular array with an S-scheme heterojunction was synthesized through the intermolecular π-stacked self-assembly of subphthalocyanine (SubPc-Br) and nanometer cadmium sulfide (CdS). This self-assembly system features a highly structured architecture and excellent stability. Experiments and ground-state differential charge calculations demonstrate that SubPc-Br and CdS form a built-in electric field during the self-assembly process, a critical factor in promoting the dissociation of electrons and holes. Additionally, this study utilized time-dependent density functional theory (TDDFT) to simulate the dynamic adsorption behavior of excited oxygen molecules on the SubPc-Br/CdS interface for the first time. The analysis of molecular charge differential density under different excited states proved that the addition of SubPc-Br molecules not only improves the photocorrosion resistance of CdS in an O₂ adsorption environment but also enhances the production of advanced reactive oxygen species under the synergistic action of h⁺ and ·O₂^–. When subjected to visible light, the degradation efficiency of minocycline (MC) achieved 96.8% within 60 min and maintained 80.3% after 5 cycles. In summary, this study highlights the feasibility of creating advanced S-scheme heterojunction photocatalysts through the strategic incorporation of organic supramolecules with semiconductor catalysts.