▎ 摘　　要

A one-pot facile, impurity-free hydrothermal method to synthesize ultrathin alpha-FeOOH nanorods/graphene oxide (GO) composites is reported. It is directly synthesized from GO and iron acetate in water solution without inorganic or organic additives. XRD, Raman, FT-IR, XPS and TEM are used to characterize the samples. The nanorods in composites are single crystallite with an average diameter of 6 nm and an average length of 75 nm, which are significantly smaller than GO-free alpha-FeOOH nanorods. This can be attributed to the confinement effect and special electronic influence of GO. The influences of experimental conditions including reaction time and reactant concentration on the sizes of nanorods have been investigated. It reveals that the initial Fe2+ concentration and reaction time play an important role in the synthetic process. Furthermore, a possible nucleation-growth mechanism is proposed. As electrode materials for supercapacitors, the alpha-FeOOH nanorods/GO composite with 20% iron loading has the largest specific capacitance (127 F g(-1) at 10 A g(-1)), excellent rate capability (100 F g(-1) at 20 A g(-1)) and good cyclic performance (85% capacitance retention after 2000 cycles), which is much better than GO-free alpha-FeOOH nanorods. This unique structure results in rapid electrolyte ions diffusion, fast electron transport and high charging-discharging rate. In virtue of the superior electrochemical performance, the alpha-FeOOH nanorods/GO composite material has a promising application in high-performance supercapacitors. (C) 2017 Elsevier Inc. All rights reserved.