Dumbbell-like Au-Fe 3 O 4 nanoparticles: a new nanostructure for supercapacitors

Monodispersed dumbbell-like Au-Fe 3 O 4 nanoparticles (NPs) were synthesized and studied for use in supercapacitors. These dumbbell NPs show Au/Fe 3 O 4 -size dependent capacitive behaviors and the 7–14 nm Au-Fe 3 O 4 NPs have the best specific capacitance of 464 F g −1 at 1 A g −1 and capacity retention of 86.4% after 1000 cycles, much larger than pure Fe 3 O 4 NPs (160 F g −1 and 72.8% retention). This capacitive enhancement is believed to arise from the Au-induced increase in electron transfer across the dumbbell-like NPs. Thise report demonstrates a new strategy to enhance oxide NP capacitance for applications in high performance supercapacitors.