Mechanistic insights into dual function of graphene oxide in preparing Starch-derived amorphous carbon for lithium storage

Abstract

Graphene oxide is demonstrated as an effective promoter for the direct conversion of starch into high-value carbon materials during carbonization process. However, the detailed mechanisms of graphene oxide in avoiding starch foaming and driving the growth of carbonaceous solid remain unclear. Herein, using thermal analysis and gas–liquid-solid products analysis, we identify the dual function of graphene oxide in the transformation of starch into porous carbon spheres. At the physical level, through a spatial confinement effect, graphene oxide coating not only separates starches from each other, but also blocks the bio-tar produced by starch foaming, inducing the secondary decomposition of tars and the formation of carbon skeleton, resulting in a high carbon yield. At the chemical level, graphene oxide coating induces the quantitative dehydration of starch, which means a controllable foaming degree and provides an adjustable pore structure of the as-obtained carbon. When serving as an anode material for lithium storage, it exhibits a high capacity of 665 mAh g−1 at 20 mA g−1 and a good cycle stable. These results provide a deeper understanding for the controllable conversion of starch into carbon driven by graphene oxide, which can potentially promote the practical application of biomass-derived carbon materials in energy storages.