Exfoliation of natural van der Waals heterostructures to a single unit cell thickness
Authors: Robert A. W. Dryfe, Sarah J. Haigh, Kostya Novoselov, Matěj Velický, Peter S. Toth, Alexander M. Rakowski, Aidan P. Rooney, Aleksey Kozikov, Colin R. Woods, Artem Mishchenko, Laura Fumagalli, Jun Yin, Viktor Zólyomi, Thanasis Georgiou
Journal: Nature Communications
Publication Date: 13 February, 2017
A new class of layered materials with promise for energy research
Scientists at The University of Manchester have ‘re-discovered’ a material, which could make the construction of two-dimensional (2D) van der Waals heterostructures easier to build. Using graphene and other 2D materials, one can construct these heterostructures by painstaking stacking of the individual components on top of each other (similar to stacking bricks of Lego) in a precisely chosen sequence. Now, a team of interdisciplinary researchers have discovered that franckeite (a mixed-metal sulphide mineral first discovered in 1893) can, like graphene, be separated to form very thin sheets using simple scotch-tape mechanical exfoliation. Franckeite consists of alternating layers of two different crystals structures – like a cake with layers of icing separating layers of sponge. When franckeite is made just a few atoms thick the layers still contain both crystal “sponge” and “icing”; providing an instant van der Waals heterostructure without the tedious mechanical stacking. Importantly, this behaviour is likely to be common to a wider family of materials and could be exploited as an alternative to artificial stacking of two-dimensional materials. This could allow scientists to simply create high-performing structures tailored to a specific application including lighting, high speed electronics and batteries.
- 2D franckeite crystals are promising for energy storage applications such as solar energy and supercapacitors due to the materials excellent electrical conductivity and remarkable electrochemical properties.
- This material was originally thought to contain only lead, tin and sulphur but careful spectroscopic analysis revealed iron and antimony were also present, although each is present only in one of the two layers.