Search

Among two-dimensional (2D) materials, such as graphene, a new family of 2D anisotropic carbides and nitrides of early transition metals (MXenes) is very interesting because of the potential applications in electronics, medicine, and photocatalysis. In this paper, preparation, morphostructural characterization, band gaps determination, and salicylic acid photodegradation ability of Ti2C MXene and six nanocomposites consisting of the MXene modified by TiO2, Ag2O, Ag, PdO, Pd, and Au are reported. It was confirmed using electron diffraction studies, energy dispersive X-ray spectroscopy, and high-resolution transmission microscopy that metals and metal oxides occur on the MXene flakes as nanoparticles in a shape of spots. The band gaps determined experimentally using Tauc's method are placed in the region of 0.90-1.31 eV. In recent years, the method of photocatalytic decomposition of pollutants using semiconductor photocatalysts and UV-vis energy has become increasingly important. The MXene based nanocomposites revealed high activity in the salicylic acid (SA) photodegradation reaction (86.1-97.1% of degraded SA after 3 h, concentration of SA initial solution 100 μM, the circulation rate of the SA solution 0.875 cm3/min). The interfacial charge transfer mechanism and the role of the metallic and metal oxide nanoparticles in the photocatalytic activity of the MXene based nanocomposites are presented and discussed.

The synthesis and characterization of Ga 1-x Mn x N thick layers are reported. The layers were prepared by the modified sublimation sandwich method (SSM) from GaN powder and powdered Mn sources and reacted with ammonia. Ga 1-x Mn x N layers having a current maximum size of 60 μm thickness and 10 mm x 10 mm area were obtained. The crystals of best crystalline quality were obtained with a growth rate of 25 μm/h. SIMS measurements showed the presence of layers containing up to 4 atom % Mn. Measurements involving X-ray diffraction (structure refinement), rocking curves, map of reflections, and EXAFS confirmed good structural properties without phase separation. The measurements carried out by a superconducting quantum interferometer showed that the material revealed typical paramagnetic properties.

Ga1-xMnxN, heavily p-type doped, should reveal ferromagnetic ordering at ambient temperatures. Here we report a method of obtaining free-standing single crystals of Ga1-xMnxN. The method of co-doping with Mn and Si was also used. The dimensions of the crystals obtained were up to 4.8 × 2.5 × 0.4 mm.