Underwater Disinfection Based on Upconverted Ultraviolet‐C Emission From Transparent Pr 3+ ‐Doped Fluoro‐Phosphate Glass‐Ceramic

ABSTRACT For underwater disinfection, ultraviolet‐C (UVC) light sources must exhibit waterproof integrity, corrosion resistance, and long‐term stability. To meet these requirements, we present a promising UVC‐emitting platform based on transparent Pr 3+ ‐doped fluoro‐phosphate glass‐ceramics (GCs). These GCs can be remotely excited in water using 450 nm blue‐light, which propagates effectively in seawater with minimal attenuation. This excitation produces strong upconverted UVC emission that aligns with the germicidal efficacy peak, achieving a 73% inactivation rate against Staphylococcus aureus . The GCs also exhibit high stability during a 30‐day seawater immersion test. Owing to their transparency, disinfection can be performed on both exterior and interior surfaces—a distinct advantage over optically opaque ceramic phosphors, which are limited to only exterior surface disinfection. This work provides a robust, low‐cost, and eco‐friendly photonic platform for remote underwater disinfection and biofouling control.