Supercapacitor electrode of nano-Co3O4 decorated with gold nanoparticles via in-situ reduction method.

Nano-Co 3 O 4 decorated with gold nanoparticles is synthesized by a simple method of in-situ reduction of HAuCl 4 by sodium citrate for energy storage application, and the effect of gold content in the product on electrochemical performance is investigated in detail. Introducing gold nanoparticles into nano-Co 3 O 4 bulk would contribute to reduce internal resistance of charge transmission. The results show that after in-situ reduction reaction gold nanoparticles imbed uniformly into nano-Co 3 O 4 with irregular nanoparticles. The gold nanoparticles decorated nano-Co 3 O 4 exhibits specific capacitance of 681 F g −1 higher than that of pristine Co 3 O 4 of 368 F g −1 . It is interesting that a good cycle life with the specific capacitance retention of 83.1% is obtained after 13000 cycles at 5 A g −1 , which recovers to initial specific capacitance value when the test current density is turned to 2 A g −1 . In addition, the device of asymmetric supercapacitor, assembled with gold nanoparticles decorated nano-Co 3 O 4 as the positive electrode and activated carbon as the negative electrode, exhibits good energy density of 25 Wh kg −1 , which is comparable to the asymmetric device assembled with normal nano-Co 3 O 4 , or the symmetric device assembled just with activated carbon. [ABSTRACT FROM AUTHOR]