Laser-induced graphene fibers

In our previous research, we found that the laser induction process on commercially available polyimide sheets is a cost-effective method for the formation of porous graphene that can be subsequently fabricated into mechanically flexible devices. Here we study the parameters required for the formation of varied laser-induced graphene (LIG) morphologies by tuning the laser radiation energy. It was found that a critical fluence point of similar to 5 J/cm(2) is needed to initiate the carbonization process regardless of the laser power. When increasing the radiation energy, the physical formation of LIG follows a fluid dynamics process in that the morphology of the LIG progressively changes from sheets to fibers and finally to droplets. We then demonstrate that a morphology of LIG nanomaterial, LIG fibers (LIGF), can be generated by this one-step laser photothermolysis process at a radiation energy >40 J/cm(2). The LIGF are hollow with a LIG wall and form vertically aligned fibers up to 1 mm in height. Microsupercapacitor (MSC) devices fabricated from LIGF and LIGF-LIG hybrids show 2x the specific areal capacitance over MSCs made entirely from LIG, thereby underscoring the potential for LIGF in flexible device applications. (C) 2017 Elsevier Ltd. All rights reserved.