fig4

Figure 4. (A) Morphology of columnar fiber produced from a tubular and Morphology of layer structure fiber produced from a flat channel. Reproduced with permission^[16], Copyright © 2019 Springer Nature; (B) SEM images of the rGOAF cross section swelling in solvent with different ratios of water and ethanol. Reproduced with permission^[53], Copyright © 2023 Springer Nature; (C) Electrical conductivity of nanofibers annealed at different temperatures. Reproduced with permission^[54], Copyright © 2021 Springer Nature; (D) Time-dependent temperature variation of GQFF under different voltages; (E) Electrothermal temperature of GQFF under different voltages. (D and E) are reprinted with permission from Ref.^[66], Copyright © 2020 American Chemical Society; (F) The enhancement factor in electrical conductivities of reduced RGG-Ag fibers as a function of the feed AgNWs weight percentage in original GGO-AgNWs fibers. Reproduced with permission^[67], Copyright © 2013 John Wiley and Sons; (G) Photothermal reaction of the microfiber under irradiation of 0.63, 1.42, and 3.20 W·cm^-2; (H) Temperature changes of the microfiber during cyclic photothermal heating and natural cooling with different irradiance; (I) Schematic showing the microstructure of the graphene-coating microfiber during the heating period. (G-I) are reprinted with permission from Ref.^[55], Copyright © 2022 Elsevier; (J) Schematic illustrations on heat allocation. Reproduced with permission^[68], Copyright © 2022 Springer Nature. SEM: Scanning electron microscope; rGOAF: reduced graphene oxide aerogel fibers; GQFF: graphene quartz fiber fabric; RGG: reduced giant graphene oxide; AgNWs: silver nanowires; GGO: giant graphene oxide; HOPG: highly oriented pyrolytic graphite; rGNF: reduced graphene nanofiber; VC: vitamin C; HI: hydroiodic acid; SA: sodium alginate; HGAF: holey graphene aerogel fiber.