Dual engineering of oxygen vacancies and Bi metal on BiOCl nanosheets for synergistically enhancing far-red emission of Eu3+

Realizing efficient far-red luminescence ( 5 D 0 → 7 F 4 transitions) from Eu 3+ ions in conventional hosts remains challenging due to the intrinsically limited energy transfer pathways. Herein, a novel dual-engineering strategy is proposed to synergistically increase the far-red emission of Eu 3+ within BiOCl nanosheets by co-introducing plasmonic metallic Bi and oxygen vacancies (OVs). Metallic Bi nanoparticles and the OVs are simultaneously incorporated into BiOCl:Eu nanosheets via a tailored solvothermal method, followed by in situ reduction. The synergistic interplay between the OVs and localized surface plasmon resonance of Bi drastically enhances the excitation harvesting and efficiency of energy transfer to the Eu 3+ activators. Consequently, the far-red emission intensity at 700 nm is remarkably enhanced 6.7-fold under 313 nm excitation, representing an unprecedented increase compared to that of pristine BiOCl:Eu. Furthermore, the precipitation of metallic Bi significantly enhances the thermal stability of the luminescence. This study provides fundamental insights into the synergistic plasmon-defect interactions within 2D semiconductors and establishes a promising pathway for use in developing high-performance far-red phosphors for application in advanced phosphor-converted white light-emitting diodes.