Enhancing electrochemical performance of ultrasmall Fe2O3-embedded carbon nanotubes via combusting-induced high-valence dopants

Doping is a reasonable solution to improve the electronic structure and surface properties of nanomaterials. Herein, we propose a rapid and simple methodology, flame synthesis, as an effective preparation strategy for incorporating high-valence metal ions (Ti4+, Sn4+, and Zr4+) into ultrasmall Fe2O3 on carbon nanotube support (i.e., M-FeO-CNT). The resulting materials exhibit not only a boosted Na+ adsorption as shown by density functional theory (DFT) calculations, but also display an increased oxygen deficiency. The electrochemical activity and charge transfer efficiency of Fe2O3 can be improved by reasonably substituting Fe3+ with Ti4+, Sn4+, and Zr4+. The electrochemical investigation of Ti-doped Fe2O3 (Ti-FeO-CNT) electrode demonstrates a splendid specific capacitance of 1.25 F cm(-2) at 1 mA cm(-2) in 1 M Na2SO4. This is significantly higher as compared to the capacitance of 0.48 F cm(-2). Flexible solid-state asymmetric supercapacitor Ti-FeO-CNT//MnO2 is verified with operating voltage of 2.0 V and stability over 3000 cycles, and delivers a high energy density of 2.14 mWh cm(-3) at power density of 25 mW cm(-3). The flame synthesis is expected to be widely applicable for the preparation of high-valence metal ions doped nanosized Fe2O3 functionalized materials, thus opening up new avenues for energy and catalysis research. (c) 2022 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.

Automated summary

In this study, a rapid and simple flame synthesis method was proposed for the preparation of nanosized Fe2O3 functionalized materials doped with high-valence metal ions. The resulting materials exhibited enhanced Na+ adsorption and increased oxygen deficiency, as well as improved electrochemical activity and charge transfer efficiency. The Ti-FeO-CNT electrode demonstrated excellent specific capacitance, and the Ti-FeO-CNT//MnO2 solid-state flexible asymmetric supercapacitor showed high energy density and stability. The flame synthesis method opens up new avenues for energy and catalysis research.