Fig. 1

a Cross-sectional SEM image of a pristine CNT fiber synthesized via the floating catalyst CVD method. The scale bar represents 20 μm. b Schematic illustration of the electroplating setup and photograph of the cathode on which pristine CNT fibers are mounted. c Schematic drawings and SEM images of the fiber surface for the spun CNT fiber and CNT–Cu microfibers with various amounts of deposited Cu. The scale bars represent 1 μm for all the samples. d Cross-sectional SEM image of a CNT–Cu microfiber belonging to the category MF5. The scale bar represents 30 μm