Cobalt Hydroxide/Oxide Hexagonal Ring-Graphene Hybrids through Chemical Etching of Metal Hydroxide Platelets by Graphene Oxide: Energy Storage Applications

The reaction of beta-Co(OH)(2) hexagonal platelets with graphite oxide in an aqueous colloidal dispersion results in the formation of beta-Co(OH)(2) hexagonal rings anchored to graphene oxide layers. The interaction between the basic hydroxide layers and the acidic groups on graphene oxide induces chemical etching of the hexagonal platelets, forming beta-Co(OH)(2) hexagonal rings. On heating in air or N-2, the hydroxide hybrid is morphotactically converted to porous Co3O4/CoO hexagonal ring graphene hybrids. Porous NiCo2O4 hexagonal ring graphene hybrid is also obtained through a similar process starting from beta-Ni0.33Co0.67(OH)(2) platelets. As electrode materials for supercapacitors or lithium-ion batteries, these materials exhibit a large capacity, high rate capability, and excellent cycling stability.