Two types of fiber-based electrodes, i.e. hierarchically structured MnO₂/graphene/carbon fiber and 3D porous graphene hydrogel wrapped copper wire, were successfully fabricated for high performance flexible all-solid-state asymmetric supercapacitors.

We report a facile and green method to synthesize a new type of catalyst by coating Pd nanoparticles (NPs) on reduced graphene oxide (rGO)-carbon nanotube (CNT) nanocomposite. An rGO–CNT nanocomposite with three-dimensional microstructures was obtained by hydrothermal treatment of an aqueous dispersion of graphene oxide (GO) and CNTs. After the rGO–CNT composites have been dipped in K₂PdCl₄ solution, the spontaneous redox reaction between the GO–CNT and PdCl₄²⁻ led to the formation of nanohybrid materials consisting rGO–CNT decorated with 4 nm Pd NPs, which exhibited excellent and stable catalytic activity: the reduction of 4-nitrophenol to 4-aminophenol using NaBH₄ as a catalyst was completed in only 20 s at room temperature, even when the Pd content of the catalyst was 1.12 wt%. This method does not require rigorous conditions or toxic agents and thus is a rapid, efficient, and green approach to the fabrication of highly active catalysts.