ABSTRACT
Novel magnetic gas sensors are characterized by extremely high efficiency and low energy consumption, therefore, a search for a two-dimensional material suitable for room temperature magnetic gas sensors is a critical task for modern materials scientists. Here, we computationally discovered a novel ultrathin two-dimensional antiferromagnet V3S4, which, in addition to stability and remarkable electronic properties, demonstrates a great potential to be applied in magnetic gas sensing devices. Quantum-mechanical calculations within the DFT + U approach show the antiferromagnetic ground state of V3S4, which exhibits semiconducting electronic properties with a band gap of 0.36 eV. A study of electronic and magnetic response to the adsorption of various gas agents showed pronounced changes in properties with respect to the adsorption of NH3, NO2, O2, and NO molecules on the surface. The calculated energies of adsorption of these molecules were -1.25, -0.91, -0.59, and -0.93 eV, respectively. Obtained results showed the prospective for V3S4 to be used as effective sensing materials to detect NO2 and NO, for their capture, and for catalytic applications in which it is required to lower the dissociation energy of O2, for example, in oxygen reduction reactions. The sensing and reducing of NO2 and NO have great importance for improving environmental protection and sustainable development.
ABSTRACT
We predict new tungsten borides, some of which are promising hard materials that are expected to be stable in a wide range of conditions, according to the computed composition-temperature phase diagram. New boron-rich compound WB5 is predicted to be superhard, with a Vickers hardness of 45 GPa, to possess high fracture toughness of â¼4 MPa·m0.5, and to be thermodynamically stable in a wide range of temperatures at ambient pressure. Temperature dependences of the mechanical properties of the boron-richest WB3 and WB5 phases were studied using quasiharmonic and anharmonic approximations. Our results suggest that WB5 remains a high-performance material even at very high temperatures.
ABSTRACT
Surfaces of rutile-like RuO2, especially the most stable (110) surface, are important for catalysis, sensing and charge storage applications. Structure, chemical composition, and properties of the surface depend on external conditions. Using the evolutionary prediction method USPEX, we found stable reconstructions of the (110) surface. Two stable reconstructions, RuO4-(2 × 1) and RuO2-(1 × 1), were found, and the surface phase diagram was determined. The new RuO4-(2 × 1) reconstruction is stable in a wide range of environmental conditions, its simulated STM image perfectly matches experimental data, it is more thermodynamically stable than previously proposed reconstructions, and explains well pseudocapacitance of RuO2 cathodes.
