Plasma-enabled graphene quantum dot-based nanofiltration membranes for water purification and dye monitoring

Nanofiltration (NF) is one of the key technologies for wastewater recycling and clean water production. How-ever, current nanofiller-based NF membranes have been hampered by the inefficient separation due to the low water transportation and self-fouling of the membranes. Here we report a unique self-diagnosis bioresource-derived nitrogen-doped graphene quantum dots (NGQDs)-based thin-film nanocomposite (TFN) membrane with controlled optical properties and tuned porous nanostructures for ultrahigh water transportation and purifica-tion. Our detailed experimental and calculation studies suggest that the NGQDs with nanoscale sizes and abundant surface functional groups can induce the formation of desired porous structures during the membrane fabrication, leading an ultrahigh water permeability of 289 L m- 2 h-1 bar- 1 (LMHB) and remarkable 99.96% separation efficiency of various organic dyes. Moreover, the stable photoluminescence (PL) emission of NGQD membranes enables the PL-based monitoring of dye-fouling during the water purification. Our work provides a green manufacturing of nanomaterials-based membranes with defined structures and an understating of mo-lecular transport in nanoscale.