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 (e.g., 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 in situ 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.