Amino acid-assisted synthesis of Fe2O3/nitrogen doped graphene hydrogels as high performance electrode material

Fe(2)O3/nitrogen-doped graphene hydrogels are synthesized by a simple hydrothermal method using amino acids with different acidities as morphology-assisting and nitrogen-doping agents, simultaneously. The Fe2O3 shows a mulberry-shape in the Fe2O3/NG-Aspartic composite, which presents a three-dimensional, loose porous network with a large specific surface area. The electrostatic and metal coordination-chelation interaction among the amino acid with different net charge, Fe3+ and graphene oxide affect the morphology, structure and final electrochemical properties of the Fe2O3/NG composites. The Fe2O3/NG-Aspartic shows a higher specific capacity, longer cycle stability and better rate capability, in comparison with the Fe2O3/NG samples prepared by using basic, neutral and non-nitrogen-doped composites. The Fe2O3/NG-Aspartic electrode provides high energy and power densities. The superior electrochemical performance of the Fe2O3/NG-Aspartic composite is ascribed to the battery-type capacity of iron oxide, the active sites introduced by the nitrogen-doping and the excellent proton-transfer due to the three-dimensional porous network structure of the graphene. (C) 2018 Published by Elsevier Ltd.