Molecularly engineered copper phthalocyanine enables flow-through electrocatalytic filtration for efficient bromate reduction.

Bromate is a toxic oxyanion disinfection byproduct whose stringent regulation calls for efficient and practical removal technologies. Electrochemical bromate reduction is promising for water treatment, yet its application remains constrained by sluggish interfacial mass transfer and the high kinetic barrier of BrO bond cleavage. Here, we developed a flow-through electrochemical filter by immobilizing copper tetraaminophthalocyanine on a carbon nanotube sponge (CuTAPc-CNTS) to simultaneously intensify bromate transport and accelerate interfacial electron transfer. Under a current density of 2.0 mA cm-2, CuTAPc-CNTS achieved 100% bromate removal within 60 min, and the flow-through configuration delivered a 3.8-fold kinetic enhancement over the flow-by mode. Mechanistic experiments combined with molecular DFT calculations suggest that bromate reduction proceeded through a pathway driven by sequential cathodic electron injection. Relative to CuPc-CNTS, amino functionalization in CuTAPc upshifts the HOMO level, narrows the energy gap, improves wettability, and increases the bromate reduction kinetics by 1.4 times. The CuTAPc-CNTS filter maintained stable performance (95.41 ± 2.81%) during 120 h of continuous operation, with a low energy consumption of 0.75 ± 0.11 kWh g-1 BrO3-. Removal efficiencies of 90.28-95.14% were obtained in the three tested real-water matrices at an influent concentration of 100 µg L-1. This work indicates that coupling molecular electronic regulation with flow-through electrofiltration is an effective strategy for bromate remediation and offers a broader framework for selective oxyanion reduction in sustainable water treatment.