Single-Step Preparation of Ultrasmall Iron Oxide-Embedded Carbon Nanotubes on Carbon Cloth with Excellent Superhydrophilicity and Enhanced Supercapacitor Performance

Nanocomposites consisting of carbon materials and metal oxides are generally preferred as anodes in electrochemical energy storage. However, their low capacitance limits the achieved energy density of supercapacitors (SCs) in aqueous electrolytes. Herein, we propose a rapid combustion strategy to construct a novel electrode architecture—ultrasmall Fe₂O₃anchoring on carbon nanotubes (FeO-CNT)—as a superhydrophilic and flexible anode for SCs. In 1 M Na₂SO₄aqueous electrolyte, such an FeO-CNT-20 anode presents a high capacitance of 483.4 mF cm^-2(326 F g^-1) at 1 mA cm^-2. The aqueous asymmetric supercapacitor devices (ASCs) assembled by FeO-CNT-20 and MnO₂present a maximum operating potential of 2.0 V with a high areal energy density of 0.11 mWh cm^-2at a power density of 0.5 mW cm^-2. The flexible solid-state ASCs display an energy density of 0.99 mWh cm^-3at 14.3 mW cm^-3. The rapidly prepared FeO-CNT not only offers an attractive electrode for SCs but also would open up exciting new avenues to the rational design and large-scale preparation of Fe₂O₃-based nanocomposites for electrochemical energy storage.