Nanomesh

The nanomesh is a inorganic nanostructured two-dimensional material, similar to graphene. It was discovered in 2003 at the University of Zurich, Switzerland.      The left image is the theoretical calculation of the same area, where the N height relative to the underlying substrate is given. The exact arrangement of Rh, N and B atoms is given for three different areas (blue: pores, yellow-red: wires). The nanomesh is a inorganic nanostructured two-dimensional material, similar to graphene. It was discovered in 2003 at the University of Zurich, Switzerland. It consists of a single layer of boron (B) and nitrogen (N) atoms, which forms by self-assembly into a highly regular mesh after high-temperature exposure of a clean rhodium or ruthenium surface to borazine under ultra-high vacuum. The nanomesh looks like an assembly of hexagonal pores (see right image) at the nanometer (nm) scale. The distance between two pore centers is only 3.2 nm, whereas each pore has a diameter of about 2 nm and is 0.05 nm deep. The lowest regions bind strongly to the underlying metal, while the wires (highest regions) are only bound to the surface through strong cohesive forces within the layer itself. The boron nitride nanomesh is not only stable under vacuum, air and some liquids, but also up to temperatures of 796oC (1070 K). In addition it shows the extraordinary ability to trap molecules and metallic clusters, which have similar sizes to the nanomesh pores, forming a well-ordered array. These characteristics promise interesting applications of the nanomesh in areas like nanocatalysis, surface functionalisation, spintronics, quantum computing and data storage media like hard drives. h-BN nanomesh is a single sheet of hexagonal boron nitride, which forms on substrates like rhodium Rh(111) or ruthenium Ru(0001) crystals by a self-assembly process. The unit cell of the h-BN nanomesh consists of 13x13 BN or 12x12 Rh atoms with a lattice constant of 3.2 nm. In a cross-section it means that 13 boron or nitrogen atoms are sitting on 12 rhodium atoms. This implies a modification of the relative positions of each BN towards the substrate atoms within a unit cell, where some bonds are more attractive or repulsive than other (site selective bonding), what induces the corrugation of the nanomesh (see right image with pores and wires). The nanomesh corrugation amplitude of 0.05 nm causes a strong effect on the electronic structure, where two distinct BN regions are observed. They are easily recognized in the lower right image, which is a scanning tunneling microscopy (STM) measurement, as well as in the lower left image representing a theoretical calculation of the same area. A strongly bounded region assigned to the pores is visible in blue in the left image below (center of bright rings in the right image) and a weakly bound region assigned to the wires appears yellow-red in the left image below (area in-between rings in the right image). See for more details. The nanomesh is stable under a wide range of environments like air, water and electrolytes among others. It is also temperature resistant since it does not decompose in temperatures up to 1275K under a vacuum. In addition to these exceptional stabilities, the nanomesh shows the extraordinary ability to act as a scaffold for metallic nanoclusters and to trap molecules forming a well-ordered array.