An exemplary apparatus facilitates the formation of carbon nanotubes with desired tip structures. The apparatus includes a reaction chamber including a gas outlet, and an evacuation device. The reaction chamber is configured for receiving a catalyst from which the carbon nanotubes grow and providing an environment for growing the carbon nanotubes. The evacuation device includes an intake connected with the gas outlet. The evacuation device is configured for reducing an inner pressure in the reaction chamber and inducing the formation of carbon nanotubes with desired tip structures. Methods for synthesizing carbon nanotubes with desired tip structures are also provided.