A novel hybrid, highly dispersed spinel Co-Mo sulfide nanoparticles on reduced graphene oxide (Co₃S₄/CoMo₂S₄@rGO), is reported as anode for lithium and sodium ion storage. The hybrid is synthesized by one-step hydrothermal method but exhibits excellent lithium and sodium storage performances. The as-synthesized Co₃S₄/CoMo₂S₄@rGO presents reversible capacity of 595.4 mA·h·g^-1 and 408.8 mA·h·g^-1 after 100 cycles at a current density of 0.2 A·g^-1 for lithium and sodium ion storages, respectively. Such superior performances are attributed to the unique composition and structure of Co₃S₄/CoMo₂S₄@rGO. The rGO provides a good electronically conductive network and ensures the formation of spinel Co₃S₄/CoMo₂S₄ nanoparticles, the Co₃S₄/CoMo₂S₄ nanoparticles provide large reaction surface for lithium and sodium intercalation/deintercalation, and the spinel structure allows fast lithium and sodium ion diffusion in three dimensions.

Nanostructured Mn₃O₄ was introduced to activated C (AC) by a novel sonochemical reaction, and the resulting nanocomposites were examined as supercapacitor electrodes. The sonication not only catalyzed the redox reaction but also promoted the diffusion of the precursors, causing the formation of coherent nanocomposites with Mn₃O₄ nanoparticles grown and uniformly distributed inside the mesopores of the AC. In addition, the extreme local condition in the sonochemical synthesis yielded an excessive amount of divalent manganese ions and oxygen vacancies. This novel microstructure endowed the sample with a superior performance, including a specific capacitance of 150 F/g compared with the value of 93 F/g for AC at a charge/discharge rate of 100 mA/g. A Li-ion capacitor delivered an energy density of 68 Wh/kg, compared with 41 Wh/kg for the AC capacitor at a power density of 210 W/kg.