Highly Efficient Electroosmotic Flow through Functionalized Carbon Nanotubes Membranes

Carbon nanotube membranes with inner diameter ranging from 1.5–7 nm were examined for enhanced electroosmotic flow. After functionalization via electrochemical diazonium grafting and carbodiimide coupling reaction, it was found that neutral caffeine molecules can be efficiently pumped via electroosmosis. An electroosmotic velocity as high as 0.16 cm s−1 V−1has been observed. Power efficiencies were 25–110 fold improved compared to related nanoporous materials, which has important applications in chemical separations and compact medical devices. Nearly ideal electroosmotic flow was seen in the case where the mobilecation diameter nearly matched the inner diameter of the single-walled carbon nanotuberesulting in a condition of using one ion is to pump one neutral molecule at equivalent concentrations.