▎ 摘　　要

The paper studied preparation and formation mechanism of free-standing 3D graphene nanoribbons (GNRs) from graphite by pulsed laser ablation in liquid. The method to fabricate freestanding graphene nanoribbons directly was simple and controllable, which does not need other precursor materials and has no byproducts. Prepared graphene nanoribbons are shown composed of up to 14 layers of graphene, spaced about 0.30-0.35 nm and have a length of hundreds of nanometers. Formation mechanism of graphene nanoribbons was proposed based on the interaction between laser and material which can be demonstrated that the exfoliation of GNRs is a carbon plasma collision connecting-graphene segments-graphene sheets-multilayer graphene-graphene nanoribbons process. The high degree of repeatability and particularity found in the obtained GNRs might suggest their unique advantages and potential applications in nano-devices and spin electronics. (C) 2016 AIP Publishing LLC.