Boron nitride nanomesh for actuated self-assembly

The boron nitride nanomesh is a corrugated, one-atom-thick layer of boron nitride on rhodium metal and has the unique property of trapping individual molecules in its pores, about 3 nanometer apart. In a recent breakthrough, accepted for publication in Nature, we demonstrated that atomic hydrogen can be intercalated between the boron nitride layer and the metal substrate, and can be used to tune the binding strength of adsorbates on the surface. In this interdisciplinary project between Austria and Belgium, we will use the boron nitride nanomesh as a platform to study reactivity, light-matter interaction and switched self- organisation of molecules at solid-liquid interfaces, opening the door towards the non- covalent and covalent functionalisation of boron nitride. This may yield new materials and applications that include sensors, nanoelectronics and lab-on-a-chip devices. The ambitious goals will be achieved by a closely integrated team with expertise in surface science, electrochemistry, spectroscopy, supramolecular chemistry and on-surface reactivity.

The composition and structure of the surface of a solid object has a very strong influence on its physical and chemical properties. Examples thereof are the fact that ice is slippery, and that certain metals such as platinum accelerate many chemical reactions, but many details of how this works are still poorly understood. In order to develop a cleaner chemical industry, and better working technologies, a much better understanding of these relationships is needed. The present bilateral project between Austria and Belgium was inspired by our 2016 Nature paper. In this paper, we described our discovery that placing very small amounts of hydrogen atoms between a single layer of hexagonal boron nitride and a metal support leads to dramatic changes of the surface properties-almost as if you could switch the well-known water repellent properties of a lotus leaf on and off by pressing a button. In our project, we were particularly interested in how we can change the way that molecules organise themselves on a surface can be changed by external effects, such as the voltage between a solid and a liquid. We studied the ordering of the molecules with a so-called scanning tunnelling microscope, which allows to visualise molecules and even single atoms. One of the most exciting discoveries from the project is that we can switch individual molecules of an organic salt between a 'bright' and a 'dark' state, and that we can read, write and erase these chemical 'bits' like the zeros and ones on which digital information storage is based. Because each molecule needs only a few square nanometres of space-a human hair is about five million nanometres thick-we estimate an information density of roughly 5 terabit per square centimetre, about one hundred times more than the most advanced industry standard today. The molecular memory works at room temperature and normal pressure and can be switched in both directions, which is important for any future applications.