One-step accurate synthesis of shell controllable CoFe₂O₄ hollow microspheres as high-performance electrode materials in supercapacitor

Multi-shelled CoFe₂O₄ hollow microspheres with a tunable number of layers (1–4) were successfully synthesized via a facile one-step method using cyclodextrin as a template, followed by calcination. The structural features, including the shell number and shell porosity, were controlled by adjusting the synthesis parameters to produce hollow spheres with excellent capacity and durability. This is a straightforward and general strategy for fabricating metal oxide or bimetallic metal oxide hollow microspheres with a tunable number of shells.