Scalable liquid method for 2D nanomaterials

RESEARCHERS in the UK have found a new way to dissolve 2D nanomaterials in solvents, which can then be used to apply a coat of the 2D nanomaterials over large surface areas.

Lead researcher Chris Howard, from University College London’s physics and astronomy department, says that most methods currently being used to coat surfaces with 2D nanomaterials, such as bismuth telluride (Bi₂Te₃), molybdenum disulphide (MoS₂) and titanium disulphide (TiS₂), are difficult to scale or can damage the material. The new process, however, solves many of these problems and could lead to new applications for 2D nanomaterials, for example in batteries, smart textiles, solar cells or for turning waste heat into electricity. The team included researchers from UCL, University of Bristol, Cambridge Graphene Centre and École Polytechnique Fédérale de Lausanne.

Howard and the team first created a ‘layered’ salt of each of the three materials, with layers of Bi₂Te₃, MoS₂ or TiS₂ separated by positively-charged lithium and potassium ion layers. The layered salts were placed in selected solvents and left to dissolve without stirring. When viewed using atomic force microscopy and transmission electron microscopy, the researchers found that this resulted in solutions of tiny, clean, undamaged sheets of 2D nanomaterials in single layers.

UCL chemical engineer Patrick Cullen said that the material salts dissolve in water in a similar way to common table salt, forming a liquid which is easy to manipulate and use on a large scale. The researchers expected the nanomaterials to form suspensions. He added that while it is “scientifically intriguing”, the solutions will be useful for industry.

“We’ve shown they can be painted onto surfaces and, when left to dry, can arrange themselves into different tiled shapes, which hasn’t been seen before. They can also be electroplated onto surfaces in much the same way gold is used to plate metals. We’re looking forward to making different 2D nanomaterials using our process and trying them out in different applications, as the possibilities are near endless,” he said.

Nature Chemistry DOI: 10/btc2