▎ 摘　　要

Using graphene oxide and hydrous ruthenium chloride as starting materials, RuO2/graphene composites were prepared via a hydrothermal reaction under different precipitation conditions by using ammonium carbonate, urea, and sodium hydrate as precipitants. The morphology and structure of the RuO2/graphene composites were characterized by SEM, TEM, XRD. Cyclic voltammetry, galvanostatic charge-discharge, and impedance measurements were carried out to test the electrochemical performance. The results revealed that the veil-like RuO2/graphene composite prepared by sodium hydrate precipitation showed better capacitance performance than a particle-like composite prepared by ammonium carbonate and urea precipitation. A disproportionation reaction from Ru3+ to Ru and RuO2 took place in the RuO2/graphene composite when using CO(NH2)(2) as the precipitant. The RuO2/graphene composite using sodium hydrate as the precipitant exhibited the optimum electrochemical performance with superior specific capacitance of 528.5 F g(-1) at 0.1 A g(-1), minimum resistance (0.4 Omega), and excellent rate performance and cycling stability, suggesting the synergetic effects of the Ru(OH)(delta)Cl3-delta precursors and graphene oxide during the hydrothermal process. (C) 2015 Elsevier B.V. All rights reserved.