Fig. 1

Structural characterization of CNT/GP micro-conduits. a Schematic illustration of CNT/GP micro-conduits in a leaves-on-branchlet nanostructure on CC substrates for high-performance supercapacitor electrodes (Note that the yellow shaded areas in the schematic indicate the selected areas to be magnified). b Bare CC substrate at low magnification (inset shows the surface of a single carbon fiber). c Uniform coverage of CNT micro-conduits on carbon fibers at low magnification. d A close-up of CNT micro-conduits on a carbon microfiber. e A CNT/GP micro-conduit in a heart shape. f A single CNT decorated with many GPs at high magnification (inset shows GPs on CNT micro-conduit array walls). g TEM image of the hierarchical structure. h High-resolution TEM image of a petal emerging from a nanotube. i Comparative Raman spectra of CNT micro-conduits and CNT/GP micro-conduits on CC substrates. Scale bars: b 500 μm (inset: 3 μm), c 300 μm, d 10 μm, e 20 μm, f 300 nm (inset: 2 μm), g 100 nm, h 10 nm