Tapered carbon nanocone tips obtained by dynamic oxidation in air

Carbon nanocones (CNCs) are conical and seamless microstructures formed by curved multiple-walled graphene layers. CNCs may be used as a kind of novel and stable atomic force microscopy (AFM) tips because of their unique conical shape and high stability. However, the relatively dull multi-walled apex structure hinders the above practical application. Here, we present an approach to sharpen the CNC tip structure to make the material more appropriate for AFM applications. Simply by oxidization in air under optimized conditions, tapered nanocone tips can be obtained. It is notable that no additional structural defects or amorphous carbon impurities were generated after the oxidation process. The sharpened CNCs are believed to be excellent AFM tips with a superb spatial resolution and high stability. Moreover, based on the step-shaped structures in the sidewalls of the processed CNCs, a possible oxidation mechanism is discussed.