Developing high-entropy materials for sustainable applications

• A team based in The University of Manchester’s Department of Materials are leading  research into inorganic high-entropy materials.
• Engineering from the atom up, they are creating previously unseen materials with emergent properties as a function of both their composition and their length scale.
• They have employed them as electrocatalysts for green hydrogen generation from water splitting.

Manchester scientists are driving research into the capabilities of inorganic high-entropy materials (HEMs). HEMs diverge away from the traditional picture of a material – i.e. something stabilised by creating bonds with other atoms – because their structure, somewhat paradoxically, is stabilised by disorder. It is this disorder makes them a potentially disruptive technology for sustainable energy generation including thermoelectric energy generation, batteries for energy storage, chemical catalysis and electrocatalysis.

Engineering new materials with exciting properties

Led by Professor David J Lewis, Head of the Department of Materials, the team of material scientists is engineering high-entropy materials from the bottom up. By adding a ‘cocktail’ of different metal atoms into the lattice, they are devising materials that are that have never been discovered before, and have some very exciting properties.

Through this work, the team have uncovered a range of capabilities in the materials. For example, their aptitude for electrocatalytic water splitting

Because HEMs contain so many different unique sites within the material, the  materials also have great potential as a disruptive technology in chemical catalysis.

Professor David Lewis explains, “It's almost like combinatorial chemistry at the atomic scale. This can be illustrated with a simple calculation. If one starts to imagine the number of unique sites in a high entropy material which contains six or more different elements, including the three nearest neighbour atoms, you’re looking at combinations in the order of 10³³. Compare that to the amount of known ‘vanilla materials’ as I would call them, well there’s only about 10¹² of those – so you can really start to produce almost unimaginable combinations of active sites within a catalyst. We have also shown that this approach can activate different structural features in electrocatalysts that lie dormant in the parent materials, and with it, improvements in efficiency”

In addition to this Professor Lewis’ team were the first to show how these materials could also exhibit quantum confinement at short (10^-9 m) length scales leading to the exciting prospect of emergent properties through both inherent disorder and from quantum effects.

Looking to the Future

Professor Lewis’ team builds high-entropy materials from the atom up, arguing in a recent perspective that this route, in general, presents the best strategy for ensuring entropic stabilisation. This means the team can control the composition of a material, from the composition of the molecular precursors that were put into the pot at the start. Despite the growth of interest in high entropy materials there still remains many challenges in their characterisation and computational simulation of the systems and Professor Lewis’ research will address these questions going forward.

Professor Lewis says: “There are still a number of outstanding challenges, and the nature of these are very interdisciplinary. I have been lucky enough to be able to collaborate with many other academics all at the same institution that share my interest in these problems. To me, therefore, Manchester is the ideal place to conduct this research.”

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Professor David Lewis is the Head of the Department of Materials at The University of Manchester. His other research interests include synthesis of compound semiconductors and inexpensive alternatives to traditional energy generation materials, 2D materials beyond graphene, and quantum dots.

Read recent papers:

• Synthesis of High Entropy Lanthanide Oxysulfides via the Thermolysis of a Molecular Precursor Cocktail | Journal of the American Chemical Society (acs.org) 
• A Low‐Temperature Synthetic Route Toward a High‐Entropy 2D Hexernary Transition Metal Dichalcogenide for Hydrogen Evolution Electrocatalysis 
• High Entropy Metal Chalcogenides: Synthesis, Properties, Applications and Future Directions 
• Synthesis of High Entropy and Entropy-Stabilized Metal Sulfides and Their Evaluation as Hydrogen Evolution Electrocatalysts | Chemistry of Materials (acs.org)

To discuss this research or potential partnerships, contact Professor Lewis via david.lewis-4@manchester.ac.uk.