Institute for Superconducting & Electronic Materials (ISEM)

Top-down patterning of topological surface and edge states using a focused ion beam

(Abdulhakim Bake, Qi Zhang, Cong Son Ho, Grace L. Causer, Weiyao Zhao, Zengji Yue, Alexander Nguyen, Golrokh Akhgar, Julie Karel, David Mitchell, Zeljko Pastuovic, Roger Lewis, Jared H. Cole, Mitchell Nancarrow, Nagarajan Valanoor, Xiaolin Wang and David Cortie, Nature Communications 14, 1693 (2023)).

A large collaboration of researchers led by the University of Wollongong has developed a process to engineer surface of topological insulators to create nanoscale conducting channels for advanced scalable electronic circuitry.

As reported in a paper in Nature Communications, investigators created patterns of topological surface edge states on antimony telluride (Sb₂Te₃) that made the surface edges conductive while the bulk layer beneath remained an insulator.

“The research answers a fundamental question if crystalline forms of topological materials can be transformed to glassy topological insulators when subjected to strong lattice disorder,” explained ANSTO Instrument Scientist Dr David Cortie, a Research Associate Investigator at the Future Low Energy Technologies (FLEET) Centre, who supervised lead author Abdulhakim Bake.

“Our research shows that, even if transformation may be possible in special cases according to past theory, there is no universal pathway and materials, such as antimony telluride, are instead converted to so-called trivial insulators”. 

Previous research by scientists at the FLEET Centre established that a topological insulator could function as the ‘on’ state of a transistor with current carried by the conducting edges.  This enables them to overcome traditional barriers for electron flow in a transistor.

“The question we addressed may sound a bit academic and uninteresting to people outside the field”, said Dr Cortie. 

“But it is rather important, in that, it potentially holds the key to designing and building the trillions of transistors needed for energy-efficient quantum electronics using a nuclear technique.   

The question of amorphous and quasicrystalline topological insulators is attracting a great deal of attention within the sector. Our work provides some of the first experiments and should be useful to many people working in this field,” said Dr Cortie. 

“On the technological front, I also believe we have unveiled a very useful pathway towards scalable topological electronics utilising ion beams to define surface electronics”.

Architecting Freestanding Room-Temperature Na-S Batteries

(Huiling Yang, Si Zhou, Bin-Wei Zhang,* Sheng-Qi Chu, Haipeng Guo, Qin-Fen Gu, Hanwen Liu, Yaojie Lei, Konstantin Konstantinov, Yun-Xiao Wang,* Shu-Lei Chou,* Hua-Kun Liu Shi-Xue Dou, Adv. Funct. Mater. 2021, In Press.)

A chain-mail catalyst Co@PCNFs with a micrograde hierarchical structure as a freestanding sulfur cathode (Co@PCNFs/S) is developed for room-temperature Na-S batteries. The electron engineering in Co@PCNFs/S, in which the electrons can transfer from the chain-mail catalysts Co@PCNFs to sulfur and polysulfides, could activate their reactivity and conversion kinetics.  The flexible electrode can effectively tolerate fast volume changes and stabilise the structure, even at a high rate. The freestanding Co@PCNFs/S cathode presents long cycling stability and high-rate capacity. This freestanding design offers a practical method for achieving high sulfur loading toward superior RT Na–S batteries. Significantly, the developed electron engineering strategy opens new opportunities for low conductivity electrode materials in various battery systems.

This research has recently been accepted by Advanced Functional Materials.

Atomic Structural Evolution of Single-Layer Pt Clusters as Efficient Electrocatalysts

(Bin-Wei Zhang, Long Ren, Zhong-Fei Xu, Ning-Yan Cheng, Wei-Hong Lai, Lei Zhang, Weichang Hao, Sheng-Qi Chu, Yun-Xiao Wang,* Yi Du,* Lei Jiang, Hua Kun Liu, Shi-Xue Dou,* Small, 2021, In Press.)

Single-layer Pt clusters, maintaining simultaneously adjacent Pt active atomic sites and Pt-Pt covalent bonds, as a new frontier of atomic structure catalysts are achieved by single Pt atoms self-assembly. It exhibits unprecedented activity and stability towards diverse electrochemical reactions, such as hydrogen reduction reaction, oxygen reduction reaction, oxygen evolution reaction, and alcohol electrooxidation, suggesting an efficient new type of catalyst. This pioneering concept will inspire future research towards building a variety of high efficiency catalysts with unique atomic arrangements, from single atoms to optimal-sized single layer.

This research has recently been accepted by Small.

Crystallographic-Site-Specific Structural Engineering Enables Extraordinary Electrochemical Performance of High-Voltage LiNi_0.5Mn_1.5O₄ Spinel Cathodes for Lithium-Ion Batteries.

(Gemeng Liang, Vanessa K. Peterson, Zhibin Wu, Shilin Zhang, Junnan Hao, Cheng-Zhang Lu, Cheng-Hao Chuang, Jyh-Fu Lee, Jue Liu, Grzegorz Leniec, Sławomir Maksymilian Kaczmarek, Anita M. D’Angelo, Bernt Johannessen, Lars Thomsen, Wei Kong Pang,* and Zaiping Guo*, Adv. Mater. 2021, 2101413)

A long-lasting high-voltage spinel cathode material has been achieved through a non-result-based crystallographic-site-specific and Wyckoff-position-specific structural engineering. This work assembles expertise in energy storage, crystallography, materials science, and advanced characterization techniques, aiming at the root causes of the instability based on the fundamental structure/function relationship of the high-voltage LiNi_0.5Mn_1.5O₄ spinel cathode. This contributes to an extraordinarily outstanding battery performance where capacity is retained at over 70% after 3000 cycles. For example, employing such materials for the purpose of battery for a cell phone or a power tool would result in a battery life of about 10 years, assuming a daily recharge. This novel engineering strategy is extendable and will pave the way to develop new cathodes for all types of metal-ion batteries.

Tuning NaO₂ formation and decomposition routes with nitrogen-doped nanofibers for low overpotential Na-O₂ batteries

(Zhi Zheng, Jicheng Jiang, Haipeng Guo, Can Li, Konstantin Konstantinov, Qinfen Gu, Jiazhao Wang, Nano Energy, 81 (2021) 105529)

A nitrogen-doped carbon nanofiber (NCF) material with high nitrogen doping levels has exhibited excellent kinetics for Na-O₂ electrochemistry. The doped nitrogen in the NCF could effectively optimize the surface adsorption energy of the reactants and intermediate, which contribute to achieve a low overpotential gap of 500 mV in Na-O₂ batteries. This result is among the best performance reported in Na-O₂ batteries and can point the way to the rational design of electrocatalytic air cathodes for rechargeable Na-O₂ batteries.

Superlattices strategy to boost electrochemical performance of aqueous zinc-ion batteries

(Weijie Li, Chao Han, Qinfen Gu,Shulei Chou, Jia-Zhao Wang, Huakun Liu, Shixue Dou ^, Adv. Energy Mater., 2020, Volume 10, 2001852)

Highlight: The PANI-V superlattice is demonstrated as a model to improve Zn²⁺ diffusion kinetics and suppress cathode dissolution. It benefits from the unique advantages of 2D superlattice structure including the enlarged layer spacing, interface modulation inducing the charge redistribution and the structure stabilization. This structural engineering strategy paves a way to develop new cathode for ZIBs.

Tunabale Electorcatalysis Boosts Room-Temperature Sodium-Sulfur Batteries

(Yanxia Wang, Yangyang Lai, Jun Chu, Zichao Yan, Yun-Xiao Wang,* Shu-Lei Chou, Hua-Kun Liu, Shi Xue Dou, Xinping Ai, Hanxi Yang, Yuliang Cao*, Adv. Mater. 2021, 33, 2100229)

Researchers from UOW’s Institute for Superconducting and Electronic Materials have prepared an elaborate multifunctional architecture that acts as a superior host for S cathode in room-temperature sodium-sulfur batteries.

Their recent research results are published in Advanced Materials.

The elaborate S host consists of an N-doped carbon skeleton and tunable MoS₂ sulfiphilic sites. Beyond the physical confinement and chemical binding of polarized N-doped carbonaceous microflowers, the MoS₂ active sites play a key role in catalyzing polysulfide redox reactions and the electrocatalytic activity of MoS₂ can be tunable via adjusting the discharge depth. The enhanced battery performance makes it an attractive option for large-scale energy storage.