Highly stable two-dimensional AgCrSe₂ membranes reinforced by polydopamine for contaminated water purification

Two-dimensional (2D) nanosheet membranes exhibit significant potential for molecular and ionic separation. Nonetheless, these membranes encounter swelling and oxidation issues when applied for the wastewater treatment in real-world scenarios. Herein, we report a novel approach to fabricate highly stable 2D membranes using AgCrSe₂ nanosheets reinforced through the in-situ polydopamine (PDA) crosslinking. These AgCrSe₂-PDA membranes exhibit outstanding resistance to both acidic and alkaline conditions, as well as to oxidizing agents (e.g., 0.3 wt% H₂O₂), thereby demonstrating superior anti-swelling and anti-oxidation capabilities. The membranes achieve nearly 100% rejection rates for negatively charged dyes and heavy metal ions complexed with ethylene diamine tetraacetic acid (EDTA), with a permeance of approximately 5.0 L m⁻² h⁻¹ bar⁻¹. Notably, the membrane maintains about 90% rejection efficiency for Cu-EDTA, with only a marginal decrease in flux, even after 140 h of cross-flow filtration. The robustness of the membrane is primarily attributed to the coordination interactions between PDA and the AgCrSe₂ nanosheets. This study offers an innovative strategy for the development of stable 2D membranes, thereby extending their applicability in the treatment of industrially contaminated water.