Abstract
Finding a low-cost and effective method at low temperatures for producing reduced graphene oxide (rGO) has been the focus of many efforts in the research community for almost two decades. Overall, rGO is a promising candidate for use in supercapacitors, batteries, biosensors, photovoltaic devices, corrosion inhibitors, and optical devices. Herein, we report the formation of rGO from two electrically insulating polymers, polytetrafluoroethylene (PTFE) and meta-polybenzimidazole fiber (m-PBI), using an excimer pulsed laser annealing (PLA) method. The results from X-ray diffraction, scanning electron microscopy, electron backscattered diffraction, Raman spectroscopy, and Fourier-transform infrared spectroscopy confirm the successful generation of rGO with the formation of a multilayered structure. We investigated the mechanisms for the transformation of PTFE and PBI into rGO. The PTFE transition occurs by both a photochemical mechanism and a photothermal mechanism. The transition of PBI is dominated by a photo-oxidation mechanism and stepwise thermal degradation. After degradation and degassing procedures, both the polymers leave behind free molten carbon with some oxygen and hydrogen content. The free molten carbon undergoes an undercooling process with a regrowth velocity (<4 m·s−1) that is necessary for the formation of rGO structures. This approach has the potential for use in creating future selective polymer-written electronics.
Highlights
Ever since graphene was discovered in 2004 by using the Scotch-tape method [1], researchers have investigated various methods for the production of bulk defect-free graphene
Similar to the reduced graphene oxide (rGO) structure obtained from PTFE, the peaks associated with GO at 3412 cm−1, 2915, ~758, 667, and ~599 cm−1 (OH out-of-plane bending) are either very weak or absent [82,83]
Raman spectroscopy indicates the presence of a multilayered structure in the rGO structures
Summary
Ever since graphene was discovered in 2004 by using the Scotch-tape method [1], researchers have investigated various methods for the production of bulk defect-free graphene. The laser writing approach is appropriate for converting carbon-source materials into rGO directly and in a single step with high spatial resolution and without affecting the properties of the adjacent materials. This method is agile, cost-effective, and well-suited for mass production. We provide a new polymer source, metapolybenzimidazole electrospun fibers (PBI, poly[2,2 -(m-phenylen)-5,5 -bisbenzimidazole]; (C20H12N4)n), for the production of rGO by the ArF excimer laser-writing method. In the case of the PBI electrospun fibers, laser annealing was performed by using 15 shots of the ArF laser with a laser fluence of 0.7 ± 0.1 J·cm−2 in air
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