In present work, we report on the use of organized TiO2 nanotube layers with a regular intertube spacing for the growth of highly defined α-Fe2O3 nano-needles in the interspace. These α-Fe2O3 decorated TiO2 NTs are then explored for Li-ion battery applications and compared to classic close-packed NTs that are both decorated with various amounts of nanoscale α-Fe2O3. We show that nanotubes with tube-to-tube spacing allow a uniform decoration of individual nanotubes with regular arrangements of hematite nano-needles. The tube spacing also facilitates the electrolyte penetration as well as yields better ion diffusion. While bare close-packed NTs show higher capacitance, e.g., 71 μAh cm-2 than bare spaced NTs with e.g., 54 μAh cm-2, the hierarchical decoration with secondary metal oxide, α-Fe2O3, remarkably enhances the Li-ion battery performance. Namely, spaced nanotubes with α-Fe2O3 decoration have an areal capacitance of 477 μAh cm-2, i.e., show up to nearly ~8 times higher capacitance. However, the areal capacitance of close-packed NTs with α-Fe2O3 decoration saturates at 208 μAh cm-2, i.e., is limited to ~3 times increase.
@article{arxiv.2004.14275,
title = {TiO$_2$ nanotubes with different spacing, Fe$_2$O$_3$ decoration and their evaluation for Li-ion battery application},
author = {Selda Ozkan and Gihoon Cha and Anca Mazare and Patrik Schmuki},
journal= {arXiv preprint arXiv:2004.14275},
year = {2020}
}