Electrospinning Spatial Building of a Secondary S‐Scheme Heterojunction in Cs ₃ Bi ₂ Br ₉ @g‐C ₃ N ₄ −SnO ₂ /PAN Nanofiber for Real‐Time Monitoring Photocatalysis

ABSTRACT Photocatalytic technology has shown great promise in addressing energy and environmental issues, yet its practical application is still remains constrained by insufficient efficiency and absence of real‐time monitoring capability. Herein, a functional core‐shell Cs ₃ Bi ₂ Br ₉ @g‐C ₃ N ₄ −SnO ₂ /PAN (CCS/PAN) nanofiber with a dual S‐scheme heterojunction is designed and fabricated via coaxial electrospinning, which significantly enhances the separation of photo‐generated carriers, broadens the visible‐light response range, and preserves robust redox capability. Benefiting from these synergistic effects, the synthesized nanofiber exhibits efficient catalytic performance, excellent mechanical properties, and good biocompatibility, achieving degradation rates of 97.6% for rhodamine B and 99.5% for tetracycline within 50 min under visible light irradiation while retaining its catalytic activity after three cycles. Simultaneously, by leveraging the distinct temperature‐dependent luminescence responses of PAN and Cs ₃ Bi ₂ Br ₉ , real‐time temperature monitoring in complex catalytic systems facilitates the identification of optimal reaction conditions, and the maximum relative sensitivity of 0.01061 K ⁻¹ is achieved at 323 K. This study provides a novel strategy for designing smart catalytic systems that enhance photocatalytic functionality with real‐time temperature feedback, demonstrating broad application potential in environmental remediation, photocatalytic hydrogen production, and industrial catalytic process monitoring.