Edge stabilities, properties and growth kinetics of graphene-like two dimensional monolayers composed with Group 15 elements

Effect of MoSe2 nanoribbons with NW30 edge reconstructions on the electronic and catalytic properties by strain engineering

Monolayer transition metal dichalcogenides (TMDs), typical two-dimensional semiconductors, have been extensively studied for their extraordinary physical properties and utilized for nanoelectronics and optoelectronics. However, the finite samples and discontinuity in the synthesis process of TMD materials definitely induce defect edges in nanoribbons and greatly influence the device performance. Here, we systematically studied the atomic structures, energetic and mechanical stability, and electronic and catalytic properties of MoSe₂ nanoribbons on the basis of experiments. Clear benefits of ZZSe-Mo-NW30 edged nanoribbons were found to evidently increase the dynamic stability according to our first-principles calculations. Meanwhile, unsaturated Mo atoms at the edge sites induced local magnetic moments up to 0.54 μ_B and changed the chemical environments of adjacent Se atoms, which acted as active sites for the hydrogen evolution reaction (HER) with a lower onset potential of -0.04 eV. The external tensile strain on these nanoribbons can have negligible effects on the electronic and catalytic properties. The onset potential of the ZZSe-Mo-NW30 edged nanoribbons only changed 0.03 eV under critical tensile strain. The atomic-scale research of edge reconstructions in TMD materials provides new opportunities to modulate the synthesis mechanism for experiments and defect-engineering applications in electrochemical catalysts.

Regulating the electronic and magnetic properties of 1T'-ReS2 by fabricating nanoribbons and transition-metal doping: a theoretical study

Monolayer 1T'-type rhenium disulphide (1T'-ReS₂) has promising applications in spintronic devices due to its unique electronic properties induced by inversion loss in the crystal structure. A prerequisite of such applications is introducing magnetism in 1T'-ReS₂. Here, we studied the electronic and magnetic properties of zigzag 1T'-ReS₂ nanoribbons (1T'-ReS₂-NRs) and further tuned their magnetic properties by transition-metal doping. Our results show that 1T'-ReS₂-NRs exhibit tunable electronic properties ranging from indirect bandgap to direct bandgap to metallic properties. Among the energy-favoured S-terminated 1T'-ReS₂-NRs, only one exhibits robust magnetic properties. The magnetic properties of the other two nanoribbons can be effectively tuned by doping with certain transition metals. Among the configurations of TM-doped 1T'-ReS₂-NRs, only those with TM atoms introduced at the edge sites are energy-favoured. The magnetic properties of TM-doped 1T'-ReS₂-NRs are mainly contributed by the TM atom, the Re and S atoms at the edges of the nanoribbons. Besides this, the bulk Re and S atoms close to the TM atom also contribute positively to the magnetism and such contributions become weaker as the atoms are farther from the TM atom. These results provide deep insights into the modulations of the electronic and magnetic properties of 1T'-ReS₂ at the atomic scale, and thus should pave an effective path for fabricating 2D materials for spintronic devices.

Revealing initial nucleation of hexagonal boron nitride on Ru(0001) and Rh(111) surfaces by density functional theory simulations

The nucleation of h-BN on Ru(0001) and Rh(111) surfaces via an energy-driven process is systematically studied by density functional theory simulations.