Structural perfection through imperfection: Defect-engineered MOF-GO composite membrane for high-performance water purification

Metal–organic frameworks (MOFs), with ultrahigh surface areas and tunable pore architectures, are promising for advanced separation membranes; however, despite advances in defect engineering for catalysis and adsorption, its potential in membrane separations remains largely unexplored. Here, we introduce a defect engineering strategy for the Zr-MOF MIP-202(Zr) through precise regulation of defect density. The defective MIP-202(Zr) was integrated with graphene oxide (GO) nanosheets via vacuum-assisted self-assembly to form hierarchical composite membranes. Notably, the defective composite membrane exhibited a two-fold increase in water permeability (up to 36.74 L m −2  h −1 bar −1 ) compared to the defect-free counterpart, while maintaining high rejection (>95%) for multiple model dyes, overcoming the conventional permeability–selectivity trade-off. The introduced defects created open sites and enhanced mass transport, collectively improving membrane hydrophilicity and water permeability. This work demonstrates defect engineering as a transformative strategy for designing high-efficiency MOF-based membranes, with significant implications for sustainable wastewater treatment and resource recovery.