A simple chemical process converts a leaf skeleton into iron carbide, which is magnetic and conducts electricity. (Image: Max Planck Institute of Colloids and Interfaces via Nanowerk.)
Via Nanowerk, researchers have developed a simple technique that could be used to make a new generation of carbide materials.
Zoë Schnepp of the Max Planck Institute of Colloids and Interfaces and her team used a simple procedure to create a complex, hierarchical microstructure of iron carbide using a biological template. By soaking a leaf skeleton in an iron acetate solution, followed by heating under nitrogen, an intact ‘magnetic leaf’ could be made.
Nanowerk describes the work as follows:
The heating process initially breaks down the biological polymers in the leaf and converts the iron acetate to iron oxide. This iron oxide coating then reacts with the carbon-rich leaf template, forming an even layer of iron carbide in an exact replica of the original leaf. Remarkably, the original biological structures such as the xylem could be seen clearly using a microscope.
Since iron carbide is conductive as well as magnetic, the use of the leaf as an electrode in a simple water splitting process was demonstrated. The base of the leaf was soldered to a copper wire and the tip submerged in the aqueous electrolyte of an electrochemical cell. Applying a voltage across the cell resulted in the evolution of bubbles of hydrogen and oxygen. The conductivity of the leaf electrode showed that the iron carbide had formed an even layer over the entire structure.
This work could lead to the development of complex metal carbide microstructures. By selecting a template from nature with specific structural characteristics, it should be possible to transfer these characteristics directly into a metal carbide product. They may offer a cheap and sustainable alternative to noble metals such as platinum in fuel cell electrodes.
The paper, “Biotemplating of Metal Carbide Microstructures: The Magnetic Leaf,” can be viewed here.