▎ 摘　　要

Multiwalled carbon nanotubes (MWCNTs) are split along the longitudinal direction to form quasi graphene oxide (QGO) by modified Hummers method and quasi graphene nanosheet/RuO2 (QGN/RuO2) composites with 40.0 wt% RuO2 loading are prepared by a one-step hydrothermal synthesis without any reducing agent. The characterization of morphology and structure shows that the amorphous RuO2 nanoparticles are uniformly dispersed on all the surfaces of QGN. The electrochemical measurements show that the QGN/RuO2 composites exhibit good capacitive properties compared to pure RuO2 and pure QGN in acidic, alkaline and even in neutral electrolytes. The specific capacitances of QGN/RuO2 in 1 M KOH, 1 M H2SO4, and 1 M Na2SO4 are 453.7, 415.7, 287.5 F g(-1). Significantly, the QGN/RuO2 composites can achieve a high voltage window of 1.6 V and greatly increase the energy density (102.2 W h kg(-1)) and power density (1600 W kg(-1)) of supercapacitors in 1 M Na2SO4 (1 A g(-1)). These results demonstrate that the QGN/RuO2 composites are a promising material for high-performance supercapacitors.