Phosphorus Nitride Imide Nanotubes for Uranium Capture from Seawater

Nuclear power plays a pivotal role in the global energy supply. The adsorption-based extraction of uranium from seawater is crucial for the rapid advancement of nuclear power. The phosphorus nitride imide (PN) nanotubes were synthesized in this study using a solvothermal method, resulting in chemically stable cross-linked tubular hollow structures that draw inspiration from the intricate snowflake fractal pattern. Detailed characterization showed that these nanotubes possess a uniformly distributed five-coordinated nanopocket, which exhibited great selectivity and efficiency in binding uranium. PN nanotubes captured 97.34% uranium from the low U-spiked natural seawater (∼355 μg L^-1) and showed a high adsorption capacity (435.58 mg g^-1), along with a distribution coefficient, K_d^U > 8.71 × 10⁷ mL g^-1. In addition, PN nanotubes showed a high adsorption capacity of 7.01 mg g^-1 in natural seawater. The facile and scalable production of PN nanotubes presented in this study holds implications for advancing their large-scale implementation in the selective extraction of uranium from seawater.