Structure and Magnetism Evolution from FeCo Nanoparticles to Hollow Nanostructure Conversion for Magnetic Applications

Hollow nanostructures have witnessed an increasing interest in emerging fields, including energy storage electrodes, nanocatalysis, photonics, and biomedical carriers. The fundamental mechanisms for hollowing conversion chemistry of complex nano-alloys are indispensable to grow such nanostructures with controlled compositions and functionalities. Here, we study the Kirkendall effect on magnetic Fe-Co bimetallic alloys with the formation of hollow nanostructures for exchange interactions. The rich diffusion kinetics of binary Fe-Co alloys accompanied by its conversion from solid, core-shell to hollow nanostructures have been captured through X-ray diffraction pattern and electron microscopy. We further report the cation exchange improved magnetic performance of hollow nanostructures by increasing the crystallinity.