Dual-template synthesis of ordered mesoporous carbon/Fe2O3 nanowires: high porosity and structural stability for supercapacitors

Abstract

Carbon/metal oxide composites are considered promising materials for high energy density supercapacitors. So far, impregnation of the oxide into ordered mesoporous carbon materials has been demonstrated either in hard-templated carbon synthesized by using ordered mesoporous silica or alumina scaffolds, or soft-templated carbon derived from surfactant micelles. The hard-template method can provide a high pore volume but the instability of these mesostructures hinders total electrode performances upon oxide impregnation. While the soft-template methods can provide a stable mesostructure, these methods produce scaffolds with a much smaller pore volume and surface area, leading to limited metal oxide loading and electrode capacitance. Herein, anodized aluminum oxide (AAO) and triblock copolymer F127 are used together as hard and soft-templates to fabricate ordered mesoporous carbon nanowires (OMCNWs) as a host material for Fe₂O₃ nanoparticles. This dual-template strategy provides a high pore volume and surface area OMCNW that retains its stable structure even for high metal oxide loading amounts. Additionally, the unique nanowire morphology and mesoporous structure of the OMCNW/Fe₂O₃ facilitate high ionic mobility in the composite, leading to >260 F g⁻¹ specific capacitance with good rate capability and cycling stability. This work highlights the dual-template approach as a promising strategy for the fabrication of next generation heterogeneous composites for electrochemical energy storage and conversion.