and duesberg@tcd.ie Platinum diselenide (PtSe 2 ) is a newly discovered 2D material which is of great interest for applications in electronics and catalysis. PtSe 2 films were synthesized by thermally-assisted selenization of predeposited platinum films and scanning transmission electron microscopy revealed the crystal structure of these films to be 1T. Raman scattering of these films was studied as a function of film thickness, laser wavelength and laser polarization. E g and A 1gRaman active modes were identified using polarization measurements in the Raman setup.These modes were found to display a clear position and intensity dependence with film thickness, for multiple excitation wavelengths, and their peak positions agree with simulated phonon dispersion curves for PtSe 2 . These results highlight the practicality of using Raman spectroscopy as a prime characterization technique for newly-synthesized 2D materials.

Atomically thin hexagonal boron nitride ( h -BN) is often regarded as an elastic film that is impermeable to gases. The high stabilities in thermal and chemical properties allow h -BN to serve as a gas barrier under extreme conditions. Here, we demonstrate the isolation of hydrogen in bubbles of h -BN via plasma treatment. Detailed characterizations reveal that the substrates do not show chemical change after treatment. The bubbles are found to withstand thermal treatment in air, even at 800 °C. Scanning transmission electron microscopy investigation shows that the h -BN multilayer has a unique aligned porous stacking nature, which is essential for the character of being transparent to atomic hydrogen but impermeable to hydrogen molecules. In addition, we successfully demonstrated the extraction of hydrogen gases from gaseous compounds or mixtures containing hydrogen element. The successful production of hydrogen bubbles on h -BN flakes has potential for further application in nano/micro-electromechanical systems and hydrogen storage.

The integrated in-plane growth of two dimensional materials (e.g. graphene and hexagonal boron nitride (h-BN)) with similar lattices, but distinct electrical properties, could provide a promising route to achieve integrated circuitry of atomic thickness. However, fabrication of edgespecific graphene nanoribbons (GNR) in the lattice of h-BN still remains an enormous challenge for present approaches. Here we developed a twostep growth method and successfully achieved sub-5 nm-wide zigzag and armchair GNRs embedded in h-BN, respectively. Further transport measurements reveal that the sub-7 nm-wide zigzag GNRs exhibit openings of the band gap inversely proportional to their width, while narrow armchair GNRs exhibit some fluctuation in the bandgap-width relationship. Transistors made of these GNRs with large bandgaps (>0.4 eV) exhibit excellent electronic performance even at room temperature (e.g. conductance on-off ratio more than 10 5 and carrier mobility more than 1,500 cm 2 V −1 s −1 ). An obvious conductance peak is observed in the transfer curves of 8-10 nm-wide zigzag GNRs while it is absent in most of armchair GNRs of similar width. Magneto-transport experiments show that zigzag GNRs exhibit relatively small magneto-conductance (MC) while armchair GNRs have much higher MC than zigzag GNRs. This integrated lateral growth of edge-specific GNRs in h-BN brings semiconducting building blocks to atomically thin layer, and will provide a promising route to achieve intricate nanoscale electrical circuits on high-quality insulating h-BN substrates.Graphene nanoribbons (GNRs), a quasi-one-dimensional graphene nanostructure, can exhibit either quasi-metallic or semiconducting behavior, depending on its specific chirality, including width, lattice orientation, and edge structure [ 1 ]. The unique properties of GNR make it a promising substitute to engineer prospective nano-electronics. There are two groups of GNRs, that differ by the edge type and are called zigzag (ZZ) and armchair (AC) [2]. Recent experiments [3,4] show that zigzag graphene nanoribbons (ZGNRs) potentially offer exotic electronic properties, such as ferromagnetism and half metallicity. Theory [5 ] predicts that all armchair graphene nanoribbons (AGNRs) are semiconducting with a band gap that is inversely proportional to their width. Normally, both ZGNRs and AGNRs have distinct electronic states and scattering properties [6,7] as well as unique chemical properties [8,9]. Practically, their edges are prone to intrinsic and extrinsic modifications [10][11][12]. Recent hetero-integration of graphene with h-BN by both van der Waals stacking [13,14] and in-plane covalent bonding [15][16][17][18][19] has exhibited an advantage in high chemical/mechanical stability, and may lead to emergent electronic properties that are fundamentally distinct from those of the constituents. However, such a hetero-structure with chirality-controllable GNRs is still difficult to achieve.In this work, we report the successful control over the chirality of mono-layer GNRs direc...