Accelerating Phosphate Transport Across Membranes via Synergistic Chemical-Electrochemical Carriers

Efficient phosphate recovery from phosphate-containing wastewater presents a dual opportunity to mitigate environmental pollution and secure nutrient supply for agriculture. Among many recovery methods, electro-membrane crystallization (e-MC) is a promising strategy for sustainable phosphate recovery, yet the low phosphate throughput of conventional electro-driven membranes constrains its efficacy. Here, we propose an ion carrier-to-carrier hopping transport principle and introduce a nanostructured electro-driven carrier-conducting membrane (e-CCM) engineered with monodispersed electro-ferrihydrite nanoparticles as a built-in phosphate carrier. This membrane architecture establishes a coordination environment where ≡FeOH acts as transient phosphate binding sites, and the applied electric field promotes directional phosphate migration, thereby accelerating phosphate permeation. Operated at 5 mA cm^-2, the resulting e-CCM membrane achieves a phosphate permeation rate of 0.92 mol m^-2 h^-1 and a recovery rate of 98.8%, outperforming state-of-the-art ion exchange membranes. We further demonstrate scalability by integrating the e-CCM membrane in e-MC for processing simulated urine, achieving 93.6% phosphate recovery and the precipitation of high-purity struvite. This work pioneers a hypothesis of carrier-conducting construction that synergizes membrane electrochemical transport with chemical affinity, establishing a scalable and energy-efficient pathway to close the phosphorus loop and advance circular resource economies.