Nanoengineering of NiO/MnO2/GO Ternary Composite for Use in High-Energy Storage Asymmetric Supercapacitor and Oxygen Evolution Reaction (OER)

Designing multifunctional nanomaterials for high performing electrochemical energy conversion and storage devices has been very challenging. A number of strategies have been reported to introduce multifunctionality in electrode/catalyst materials including alloying, doping, nanostructuring, compositing, etc. Here, we report the fabrication of a reduced graphene oxide (rGO)-based ternary composite NiO/MnO2/rGO (NMGO) having a range of active sites for enhanced electrochemical activity. The resultant sandwich structure consisted of a mesoporous backbone with NiO and MnO2 nanoparticles encapsulated between successive rGO layers, having different active sites in the form of Ni-, Mn-, and C-based species. The modified structure exhibited high conductivity owing to the presence of rGO, excellent charge storage capacity of 402 F center dot g(-1) at a current density of 1 A center dot g(-1), and stability with a capacitance retention of similar to 93% after 14,000 cycles. Moreover, the NMGO//MWCNT asymmetric device, assembled with NMGO and multi-wall carbon nanotubes (MWCNTs) as positive and negative electrodes, respectively, exhibited good energy density (28 Wh center dot kg(-1)), excellent power density (750 W center dot kg(-1)), and capacitance retention (88%) after 6000 cycles. To evaluate the multifunctionality of the modified nanostructure, the NMGO was also tested for its oxygen evolution reaction (OER) activity. The NMGO delivered a current density of 10 mA center dot cm(-2) at the potential of 1.59 V versus RHE. These results clearly demonstrate high activity of the modified electrode with strong future potential.

Automated summary

Designing multifunctional nanomaterials for high performing electrochemical energy conversion and storage devices has been challenging. The researchers in this study reported the fabrication of a reduced graphene oxide-based ternary composite NiO/MnO2/rGO (NMGO) that had a range of active sites for enhanced electrochemical activity. The modified structure exhibited high conductivity, excellent charge storage capacity, and stability. The NMGO//MWCNT asymmetric device demonstrated good energy density, excellent power density, and capacitance retention.