Functionalization of carbon nanotube AFM probes using tip-activated gases

Multiwalled carbon nanotube (MWNT) probe microscopy tips have been functionalized with gases, activated in a transient arc produced at the tip ends. Adhesion measurements between these tips and hydroxyl-terminated monolayers versus pH reveal that MWNT tips reacted in O2, H2 and N2 display acidic, pH-independent and basic properties, respectively. MWNT tips derivatized in O2/N2 and H2/N2 mixtures demonstrate the greater reactivity of carbon nanotubes towards O2 and H2, respectively. Moreover, the chemical reactivity of tips functionalized in N2 suggests termination in aromatic nitrogen heterocycles. Tip-activated gas functionalization of MWNTs provides facile generation of chemically sensitive nanoprobes.