A facile solution-free etching preparation of porous graphene nanosheets with high performances for lithium storage

•A novel solution-free method is developed to prepare porous graphene nanosheets.•Ferrocene is selected as precursor to form γ-Fe2O3 nanoparticles as etchant.•The phase transitions and pore forming process have been systematically studied.•Porous graphene nanosheets have good rate capability and high reversible capacity.

Porous graphene nanosheets (PGNs) have attracted tremendous attention and research interest due to their unique porous structure in combination with inherent properties of graphene such as large specific surface area and excellent conductivity. Although several methods have been developed to prepare PGNs, solution-free synthesis of PGNs which could avoid the stacking of graphene nanosheets (GNs) in the solvent system has not been referred. Herein, we report a facile solution-free synthesis of PGNs through the etching of GNs by hematite nanoparticles (NPs) that derived from ferrocene. Microstructure and composition analyses reveal that ferrocene primarily transfers to α-Fe2O3 NPs depositing on GNs at 180 °C and then to γ-phase at 900 °C under Ar atmosphere. During high-temperature treatment, the nano-channels form accompanying the reduction of γ-Fe2O3 NPs by consuming the lattice carbon atoms of GNs. The PGNs electrode retains a high reversible specific capacity of 963.4 mA h g−1 at 100 mA g−1 after rate tests and 200 activated cycles, and also exhibits good cycling stability and excellent rate performance. PGNs prepared by this solution-free etching method should be a promising high-performance support and conductive agent for LIBs.