2D-boron

08 April 2016 - Chemical Zoo

boron sheets Feng 2016.PNGIf you want to read up on the new two-dimensional boron sheets unrolled by Baojie Feng et al. you have options: choose either 'Experimental Realization of Two-Dimensional Boron Sheets' as published on arxiv (link, free-access) submitted 16 december 2015 or choose "Experimental realization of two-dimensional boron sheets" as published in Nature Chemistry (doi), paywall / sci-hub.io :-) submitted 17 july 2015. Somehow Feng & associates were in a hurry to get their research published and the Nature Chemistry editors / reviewers were not. So what was all the fuzz about? The authors of either article note that while carbon is more than fond of flat sheets, boron prefers cages as in borospherene or if it must, lousy 36-atom not-even-flat sheets of borophene. The B40 anion was featured earlier in this blog. Still a far cry from 2-dimensional sheets. The Feng team evaporated 99.9999% boron on silver at 570K / 6x10-11 torr. The formation of boron islands is all in the STM evidence. The layers are of the type of hexagonal boron rows. Annealing at 650K produced a second type of sheet with a different hole / vacancy configuration. Interestingly both layer types were not among the various computationally predicted types. The formation of 3D-structures at higher boron loading hampers the development of larger sheets. On the other hand the boron layer is glued to the silver surface with the same strength as graphite to copper so 2D-boron should be able to detach itself.

Rik