Crab shells could help pave the way for sustainable electronics

As the consumer electronics industry continues to grow, there is also a growing demand for the raw materials and metals used to make electronic components. Scientists at Osaka University have discovered a sustainable alternative to these finite resources in an unexpected place – crab shells. 

The researchers have developed a nanocarbon material for electronics applications made from chitin, one of the most important biopolymers in nature that is found abundantly in crab shells. 

According to the experts, nanocarbon materials show significant promise for use in electronic devices. Those with porous three-dimensional (3D) structures provide efficient networks for the transport of charge as well as electrolytes and reactants. 

Energy flow through nanocarbon materials can be made even more efficient with the addition of imperfections – known as defects – in the form of nitrogen and other chemical elements.

Porous nanocarbon materials have been previously developed using synthetic polymers and biomass for energy storage, sensing, and electrocatalysis. However, many of these materials were designed with non-renewable resources or require multiple steps to prepare the network and introduce the defects.

The researchers have now developed 3D porous defective nanocarbon materials through the simple pyrolysis, or thermal decomposition, of chitin nanofiber paper. Chitin is an ideal candidate for engineering electronics materials because it contains nitrogen atoms and acts as its own source of defects.

“We were able to control various properties of the final nanocarbon materials by pyrolyzing the chitin nanofiber paper at different temperatures,” said study first author Luting Zhu. “The pore structure, specific surface area, and electrical resistivity all varied with the pyrolysis temperature, providing us with a useful means of tuning the material for specific applications.”

The pyrolyzed chitin nanofiber papers were successfully used as photosensors – exhibiting lower resistance when exposed to light. They also proved effective as supercapacitor electrodes, with a higher capacity to store an electrical charge than many other nanocarbon materials. This indicates that chitin nanofiber papers have great potential for use in energy storage.

“In order to translate laboratory findings into products that make a significant impact in the real world it is important to streamline processes, which is why we are excited about our simple pyrolysis treatment,” explained study co-author Hirotaka Koga. “Furthermore, our successful use of a renewable resource that is generally considered a waste product demonstrates the viability of sustainable electronics.”

The study is published in the Journal of Materials Chemistry C.

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By Chrissy Sexton, Earth.com Staff Writer