Facile synthesis of nanoporous Fe2O3 with internal nanocavities for highly reversible lithium storage

Abstract Citrate-capped magnetites (cit-Fe3O4) are electrostatically conjugated with 3-aminopropyl trimethoxysilane (APS), forming APS-complexed Fe3O4 (A-Fe3O4). Atmospheric calcination induces the direct conversion of A-Fe3O4 into silica-coated Fe2O3 (Fe2O3@SiO2) while preserving its nanoscale dimension (∼15 nm). One-pot chemical etching of the Fe2O3@SiO2 leads to iron oxide particles (Fe2O3) with internal nanocavities, so called nanoporous Fe2O3. After 200 cycles at the current density of 100 mA g−1, the nanoporous Fe2O3 delivers a high reversible capacity of ∼700 mAh g−1 without distinct capacity fading. The excellent cycling stability of the nanoporous Fe2O3 is attributed to the superior buffering effect contributed by its nanoscale dimension and multiple internal nanocavities inside particles, which significantly retard the pulverization process of iron oxide particles. The facile one-pot synthesis of the nanoporous Fe2O3 is an effective, inexpensive route in designing high-performance electrode materials for sustainable energy conversion and storage applications.