Recyclable and flexible Bi(Ho³⁺-Yb³⁺)OBr/g-C₃N₄ composite porous fiber for efficient water purification and real-time temperature sensing

Herein, an electrospinning porous nanofiber with large specific surface area, excellent flexibility, remarkable tensile strength, and high stability of thermal degradation has been developed by loading Ho³⁺/Yb³⁺ co-doped BiOBr/g-C₃N₄ (BHY/CN) heterojunction photocatalysts on polyacrylonitrile (PAN) nanofibers. The optimized BHY/CN-2 nanofiber demonstrates outstanding photocatalytic activity for the degradation of 98.83% tetracycline (TC, 60 min) and 99.06% rhodamine B (RhB, 90 min) under simulated sunlight irradiation, and maintains a high level of reusability and recycling stability in three cycles. In addition, temperature monitoring of the catalytic degradation process can be feedback by (⁵F₄, ⁵S₂) → ⁵I₈ and ⁵F₅ → ⁵I₈ radiation transitions of Ho³⁺ with excellent sensitivity. More importantly, the nanofiber luminescence performance is enhanced by the doping of g-C₃N₄, which maintain the effective upconversion luminescence properties even in water, providing a reliable reference for real-time monitoring and feedback of the operating temperature, and further expanding the application fields of photocatalysts. © The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature 2023.