These are bright-field scanning transmission electron microscope images, composed elemental mappings and illustrations of copper alloy nanoparticles containing 30% nickel before and after oxidation treatment at 85°C and 85% relative humidity. Image: Copyright 2016 Toyohashi University of Technology.
These are bright-field scanning transmission electron microscope images, composed elemental mappings and illustrations of copper alloy nanoparticles containing 30% nickel before and after oxidation treatment at 85°C and 85% relative humidity. Image: Copyright 2016 Toyohashi University of Technology.

The ability to fabricate electronics on flexible or curved surfaces will lead to the use of electronics in more varied applications, allowing mobile phones or smart watches to be fabricated at home using a printer in the future. However, the low performance and high cost of current conductive inks is limiting the development of printed electronics.

Now, researchers at Toyohashi University of Technology in Japan and Duke University have shown that copper alloy nanoparticles can be used to produce affordable conductive inks with high oxidation resistance. As the researchers reveal in Scientific Reports, to produce these nanoparticles, they electrically exploded copper alloys or twisted metal wires in water with a mild reducing agent (vitamin C).

"We have been working on developing a 'wire explosion' method to produce novel metal nanoparticles. Then, we found that some of the produced copper alloy nanoparticles possessed both high oxidation resistance and low electrical resistance," explains assistant professor Go Kawamura from Toyohashi University of Technology. "Moreover, the nanoparticles have the advantage of being inexpensive because the production process is very economical and environmentally friendly."

As a result, copper nanoparticles alloyed with 1% tin, 5% silver, 5% nickel or 30% nickel had electrical conductivities similar to that of copper. Unlike copper, however, the nanoparticles still remained conductive when exposed to temperatures of 85°C and 85% relative humidity for 24 hours.

With further improvement of the electrical conductivity and oxidation resistance, copper alloy nanoparticles prepared by wire explosion could be used for the production of high-performance affordable conductive inks. The researchers also hope that this work leads to further investigation into combining wire explosion with chemical modification of the explosion medium as a way to control the composition and surface chemistry of nanoparticles.

This story is adapted from material from Toyohashi University of Technology, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier. Link to original source.