These images show the completed triple layer nanowires. Image: KAUST.
These images show the completed triple layer nanowires. Image: KAUST.

By combining multiple nanomaterials into a single structure, researchers at the King Abdullah University of Science & Technology (KAUST) in Saudi Arabia have been able to create hybrid materials that incorporate the best properties of each component and outperform any single substance.

The researchers have developed a controlled method for making triple-layered hollow nanostructures consisting of a conductive organic core sandwiched between layers of electrocatalytically active metals. The potential uses for these nanostructures, which are reported in a paper in Nature Communications, range from better battery electrodes to renewable fuel production.

Although several methods exist to create two-layer nanomaterials, making three-layered nanostructures has proven much more difficult, says Peng Wang from KAUST’s Water Desalination and Reuse Center. Wang co-led the current research with Yu Han, a member of the Advanced Membranes and Porous Materials Center at KAUST. This difficulty inspired the researchers to develop a new, dual-template approach, explains Sifei Zhuo, a postdoctoral member of Wang's team.

The researchers grew their hybrid nanomaterial directly on carbon paper – a mat of electrically conductive carbon fibers. They first produced a bristling forest of nickel cobalt hydroxyl carbonate (NiCoHC) nanowires on the surface of each carbon fiber. Each tiny inorganic bristle was coated with an organic layer called hydrogen-substituted graphdiyne (HsGDY).

Next came the key dual-template step. When the team added a chemical mixture that reacts with the inner NiCoHC, the HsGDY acted as a partial barrier. Some nickel and cobalt ions from the inner layer diffused outward, where they reacted with thiomolybdate from the surrounding solution to form an outer nickel- and cobalt-co-doped molybdenum disulfide (Ni,Co-MoS2) layer. Meanwhile, some sulfur ions from the added chemicals diffused inwards to react with the remaining nickel and cobalt. The resulting substance had the structure Co9S8, Ni3S2@HsGDY@Ni,Co-MoS2, in which the conductive organic HsGDY layer is sandwiched between two inorganic layers.

This triple layer material showed good ability at electrocatalytically splitting water molecules to generate hydrogen, a potential renewable fuel. The researchers also created other triple-layer materials using the same dual-template approach.

"These triple-layered nanostructures hold great potential in energy conversion and storage," says Zhuo. "We believe it could be extended to serve as a promising electrode in many electrochemical applications, such as in supercapacitors and sodium-/lithium-ion batteries, and for use in water desalination."

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