Internally illuminated photocatalytic membrane via integrated optical Fibers to overcome photon transport limitations in water treatment

Photocatalytic membranes (PMs) offer a promising platform for simultaneous pollutant degradation and separation in water treatment. However, their performance is fundamentally constrained by inefficient photon delivery, particularly under turbid or light-limited conditions. Here, we introduce an Integrated Photocatalytic Optic Fiber Membrane (IPOFM) that embeds optical fibers directly within the membrane matrix to enable spatially distributed internal illumination. Using the same membrane material, we systematically compared internal and external illumination configurations to isolate the effects of photon delivery pathways. Under visible light irradiation, internal illumination increased the apparent degradation rate constant by ∼22% and achieved 3.9-fold higher apparent quantum yield (AQY) relative to external illumination, reflecting enhanced photon utilization efficiency rather than changes in intrinsic photocatalyst activity. Monte Carlo simulations predicted a ∼3.92-fold increase in photon absorption efficiency, supporting the experimental trends. The internally illuminated IPOFM also exhibited higher antifouling and self-cleaning performance, with flux recovery ratios (FRR) of 94.50% after repeated cycles, compared to the externally illuminated configuration (55.01%). This work demonstrates a membrane- scale illumination strategy that decouples photocatalytic efficiency from external optical path limitations, thereby establishing an engineering design framework for light-limited water treatment systems.