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Innovative method in designing tiny 3D materials may bring fuel cells efficiency

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Science & Technology, Australia (Commonwealth Union) – The global fuel crisis has further elevated the need for alternative fuel sources. The disruption to the fuel supply has resulted in power cuts as well as incentives where authorities in certain parts of the world have even gone to the extent of paying people to save energy or consume less energy.

Researchers from The University of New South Wales (UNSW), recently revealed a novel method to form tiny 3D materials that may eventually make fuel cells such as hydrogen batteries cheaper and more sustainable.

The study that was published in Science Advances, that had scientists from the School of Chemistry at UNSW Science demonstrate how to to sequentially ‘grow’ interconnected hierarchical structures in 3D at the nanoscale containing unique chemical and physical properties to back energy conversion reactions.

Hierarchical structures within chemistry are configurations of units like molecules within an organization of other units that themselves can be ordered. Similar phenomena can be witnessed in the natural world, such as in flower petals and tree branches. The full potential of these structures goes beyond the visibility of the human eye, which is at the nanoscale according to researchers.

With the application of conventional methods, researchers have found it difficult to copy these 3D structures having metal components on the nanoscale. To learn how tiny these 3D materials are required to be, in 1 centimeter, there are 10 millimeters, and counting 1 million tiny segments in just 1 of those millimeters, each of those would be 1 nanometer (nm).

“To date, scientists have been able to assemble hierarchical-type structures on the micrometre or molecular scale,” said senior author of the study Professor Richard Tilley, who is Director of the Electron Microscope Unit at UNSW. “But to get the level of precision needed to assemble on the nanoscale, we needed to develop an entirely new bottom-up methodology.”

The scientists applied chemical synthesis, which is an approach that constructs complex chemical compounds using simpler ones. They carefully grew hexagonal crystal–structured nickel branches on cubic crystal–structured cores to produce 3D hierarchical structures with dimensions of approximately 10-20 nanometers.

The resulting interconnected 3D nanostructure contains a high surface area, high conductivity as a result of the direct connection of a metallic core and branches, having surfaces capable of being chemically modified. These properties bring about the perfect electrocatalyst support, which is a substance that assists in speeding up the rate of reactions, in the oxygen evolution reaction, an essential procedure for energy conversion. The nanostructure’s properties were evaluated applying electrochemical analysis from state-of-the-art electron microscopes given by the Electron Microscope Unit.

“Growing the material step by step is a contrast to what we do assembling structures at the micrometre level, which is starting with bulk material and etching it down,” says the lead author of the study Dr Lucy Gloag, a Postdoctoral Fellow at the School of Chemistry, UNSW Science. “This new method allows us to have excellent control over the conditions, which lets us keep all of the components ultra-small – on the nanoscale – where the unique catalytic properties exist.”

In the next stage of the study, the researchers will explore the modification of the surface from the material with platinum, which is a much better catalytic metal however it is less economical. About a 6th of the cost of an electric car alone will be the platinum powering for this fuel cell.

“These exceptionally high surface areas would support a material like platinum to be layered on in individual atoms, so we have the absolute best use of these expensive metals in a reaction environment,” said Professor Tilley.

The innovation is likely to be of key interest for researchers of nanotechnology and alternative energy.

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