Concentration gradient induced in situ formation of MOF tubes.

The concentration gradient arising from the migration of metal ions and organic ligands could transform alginate fibres into MOF tubes in an aqueous environment. The tubes (10–20 μm thick) formed by alginate and ZIF-67 particles (∼500 nm and ∼1.5 μm) show high performance in contaminant removal. The facile preparation of tubular MOF composites would facilitate the application of MOFs.