Flowers and walnuts are just some of the shapes scientists in China have made in a technique developed for making selenium microstructures.
 
A team of researchers lead by Yi Xie at the University of Science and Technology of China, Hefei, used an approach called solution-phase deposition to make different types of porous selenium microstructures. These porous structures have the potential for use in areas such as hydrogen storage and high-energy batteries, said Xie.

The structures form when a mixture of a sodium-selenium mixed-metal oxide (Na₂SeO₃) and an amine-containing compound such as hydrazine hydrate are heated in the presence of zinc foil. The coordination of the amine-containing molecules with zinc ions on the foil is thought to play an essential part in controlling the morphology of the microstructures. 

'Various selenium microstructures can be fabricated on a large scale by simply adjusting the experimental parameters such as ratio of reactants and the type of substrate,' said Xie. The team have formed porous structures ranging from flower-like patterns and lotus-root microspheres to walnut-like spheres and ear-like materials using the technique.

Jean-Marie Nedelec, a materials scientist at Blaise Pascal University, Clermont-Ferrand, France, said the technique provides one of the few examples of porous selenium preparation that has great potential for use in hydrogen storage. 'In my opinion, the main interest of the work lies in the simplicity of the procedure and its applicability to other materials making it a source of inspiration for materials chemists,' he said.

Katherine Davies