Covalent organic framework catalytic membranes for durable multitasking water purification

Heterogeneous catalysis has emerged as a promising approach for sustainable and efficient water purification due to its high catalytic efficacy and low energy consumption. However, the complex nature of nontraditional water resources (<i>e.g.</i>, trace toxic metals, organic molecules, and high salinity) leads to gradual catalyst deactivation, hindering large-scale implementation. Here we introduce the concept of sieving-coupled nanoconfined catalytic water pollutant conversion for rapid purification of complex water sources. This dual-function system was achieved by integrating <i>in situ</i> recycled palladium nanoclusters within covalent organic framework (COF) membranes. The strong interaction between Pd and the pyrazine nitrogen in the COF facilitates the formation of a Pd layer within a 40 nm-thick COF nanofilm. The resultant Pd⁰-TpPz membrane exhibited a high permeability of 85.4 L m^-2 h^-1 bar^-1 while achieving 99.8% for Eriochrome black T. This precise-sieving effect of the membrane enables the efficient catalytic reduction of various pollutants such as rhodamine B (RhB), Cr(vi), and 4-nitroaniline in complex systems. The reported Pd⁰-TpPz membrane evinced favorable long-term stability, recyclability, antimicrobial activity, and acid-base resistance (pH = 2-12), demonstrating its high potential for water treatment. This work paves the way towards the development of sieving-coupled nanoconfined catalysis for rapid water purification.