Metallic nanoparticles' magnetic properties are exploited in fields as diverse as biotechnology and magnetic recording. However, the instability of pure metal particles towards oxidation in air or in solution limits their application, making nanoparticle stabilisation an important research goal.

During their research into magnetically separable catalysts, Ferdi Schüth and his colleagues at Max Planck Institut für Kohlenforschung in Mülheim, used a 'core-shell' pyrolysis strategy to deposit a protective, stable carbon layer on their catalytic cobalt nanoparticles. The coated particles were remarkably stable under harsh acidic and basic conditions.

The researchers also considered using the nanoparticles as templates to prepare hollow graphite shells with unusual properties. If isolated empty shells can be made they foresee applications in chemical storage or electronic devices.

This versatile approach to making stable magnetic nanomaterials will find applications in catalysis and beyond.

Sula Armstrong