Old pieces of bread can be transformed into precisely shaped electrodes using water and heat. The bread-based components could replace metal electrodes in devices while reducing the hundreds of tonnes of bread wasted daily.
鈥淏read has all sorts of stuff in it, such as starch, protein and water,鈥� says at the University of Pennsylvania. 鈥淵ou can just heat it at a really high temperature without oxygen and you get the carbon backbone out of that.鈥�
This leftover carbon material is a good electrical conductor. But previous approaches didn鈥檛 allow for control of the shape of the final carbon electrode as it was heated, reducing its practical value. The technique was 鈥渞eally limited by the geometry of a slice of bread鈥�, says Bujdos.
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That led Bujdos and his colleagues to test different processes to carbonise bread while keeping the shape of the heated electrode intact. In one trial, they used a 3D-printed mould to manually stamp pieces of bread into a zig-zag shape before heating. In another, they blended pieces of bread into small particles and mixed them with water before heating this doughy material on the 3D-printed mould. They used slices of wholemeal bread in all tests.
The researchers found that the bread electrodes retained the zig-zag shape using both methods, but the blending approach produced a denser, sturdier form. The zig-zag pattern doesn鈥檛 have a particular function, but it was selected to demonstrate how well they could control the electrode鈥檚 shape. 鈥淵ou get tighter control over the geometry,鈥� says Bujdos. 鈥淭he next step will be to figure out what kind of circuit we can build with this.鈥�
In earlier work, the researchers used bread-based water. But Bujdos says the added control could enable other applications, from generating hydrogen fuel to replacing copper wires with bread-based wires.
Making electrodes at home from your own uneaten crusts will be a challenge, however. The process requires temperatures of 800掳C (1500掳F) in a furnace without oxygen.
Royal Society Open Science
