Self-assembled hydrothermal synthesis for producing a MnCO3/graphene hydrogel composite and its electrochemical properties

As ultrathin and flexible materials, graphene sheets are versatile building blocks for fabricating graphene-based functional composite materials for widespread applications. In this paper, we demonstrated a facile approach to prepare MnCO3/graphene hydrogel (MGH) composites via a hydrothermal process. The MnCO3 nanoparticles are 50-100 nm in size and are deposited on graphene sheets' surfaces as spacers to prevent graphene sheets from restacking. A combination of deposited MnCO3 nanoparticles and hydration of the hydrogel could effectively keep the neighboring graphene sheets separated. The obtained MGH nanocomposite presents a high specific capacitance (C-s) of 645.5 F g(-1) at 0.5 A g(-1) in a three-electrode system, suggesting that it is a robust candidate as a supercapacitor electrode material.