Figure 1From: Single-step electrochemical functionalization of double-walled carbon nanotube (DWCNT) membranes and the demonstration of ionic rectificationTEM and SEM images of DWCNT and schematic diagram of functionalized anionic dye. (A) TEM image of DWCNTs (purchased from Sigma-Aldrich). (B) SEM image of as-made DWCNT membrane in the cross-sectional view. (C) Schematic diagram of functionalized anionic dye on the CNT tip playing as gatekeeper (gray, C; red, O; blue, N; yellow, S).Back to article page