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The electronic structures and thermal properties of hexagonal XO ($\mathrm{\text{X}}=\mathrm{\text{Be}}$, Mg and Sr) nanosheets are studied within the density functional theory. The thermal properties are computed using the specified structural parameters of the electronic properties. Thermal properties including entropy, enthalpy, free energy and heat capacity for XO nanosheets are reported. It is found that BeO is an insulator, whereas MgO and SrO are semiconductors based on the energy gap value within GGA and HSE06. The electronegativity and bonding nature of XO nanosheets differ, resulting in considerable variations in thermodynamic parameters that follow a similar pattern as a function of temperature. Enthalpy and entropy increase with temperature whereas free energy falls, owing to a change in the binary oxide internal energy of the system and the electron density distribution. Thermal energy absorbed by the lattices grows with increasing temperature to the point at which all of their modes are activated and the systems start to display unharmonicity deviating from a linear dependence. Variable parameter ranges for XO nanosheets are useful in the development of thermoelectric nanodevices.

Nanosheets of cobalt and nickel hydroxides nanosheets were prepared by delamination of layered compounds, Co^II(OH)_1.73(DBS)_0.27·0.87H₂O (Co-DBS, DBS = dodecylbenzene sulfonate) and Ni^II(OH)_1.63(DBS)_0.37·1.24H₂O (Ni-DBS), respectively. Powder X-ray diffraction analyses of the layered compounds revealed lattice parameters of a₀ = 3.07 Å and c₀ = 30 Å (Co-DBS) and a₀ = 3.09 Å and c₀ = 30 Å (Ni-DBS) in the hexagonal system. Dispersions of Co-DBS and Ni-DBS in 1-butanol produced colloidal solutions of nanosheets, [Co-DBS]_delam and [Ni-DBS]_delam, respectively. Poly(vinylpyrrolidone) (PVP) was dissolved in [Co-DBS]_delam and [Ni-DBS]_delam and the mixtures were dried to yield Co-PVP and Ni-PVP, respectively. These nanosheets measured 150-500 nm for [Co-DBS]_delam and 135-400 nm for [Ni-DBS]_delam by means of dynamic light scattering. Atomic force microscopy images showed lateral dimensions of 100-500 nm for [Co-DBS]_delam and 50-100 nm for [Ni-DBS]_delam. In the former image, the cobalt hydroxide nanosheets had a fairly flat terrace structure with thickness of 3.1-3.6 nm and with aspect ratios of 30-150, whereas in the latter image dome-like nanosheets of nickel hydroxide with height of 2.2-2.3 nm were confirmed. These nanosheets were regarded as monolayer. Magnetization experiments at 1.8 K showed hysteresis loops for Co-DBS, Co-PVP, Ni-DBS, and Ni-PVP.

Magnetic and optical properties of (Mn, Fe)-doped SiC nanosheet (NS) are investigated using first principle calculations based on Density Functional Theory (DFT) within the Full Potential Linearized Augmented Plane Wave (FP-LAPW) method. The Generalized Gradient Approximation (GGA) shows that doping SiC NS by Mn has a half-metal ferromagnetic behavior when one Si atom is replaced by Mn or Fe. We also study the effect of (Mn, Fe) doping on optical properties of SiC NS such as absorption coefficient and optical reflectivity as function of energy. We found that doping SiC NS increases the absorption coefficient, the optical conductivity and the reflectivity in the visible region.

In this study, we synthesized copper hydroxide nanosheet and investigated its electrochemical property and how to deposit it with a uniform amount. The precursor of the nanosheet was a layered copper hydroxide synthesized by the ion exchange of dodecylbenzene sulfonate (DBS) with acetate in Cu₂(OH)₃(CH₃COO)⋅H₂O. The nanosheet was prepared by delamination of the layered copper hydroxide by dispersion in 1-butanol. Atomic force microscopy (AFM) images of the nanosheets showed lateral dimensions of ca. 2 $\mu$m with the height of ca. 4.5 nm. Cyclic voltammogram of the nanosheet in basic solution showed two cathodic peaks and two anodic peaks similar to the copper oxide electrode. To deposit the nanosheet, a quartz glass slide was dipped in the dispersion of the nanosheet in 1-butanol and dried after washing. This procedure was repeated and the ultraviolet (UV) and visible (Vis) light absorption spectrum of the slide was measured. The absorbance of the slide increased in direct proportion to the number of times of the dip-and-dry procedure. Thus, we confirmed that a controlled amount of nanosheet was deposited on the quartz glass.

In this work, we report the morphology and optical properties of zinc oxide (ZnO) layers prepared by dry thermal oxidation at different annealing conditions. Morphology studies using scanning electron microscope (SEM) show that the amount of nanowires and nanosheets increases with the introduction of a flow of O₂ gas. High-resolution X-ray diffraction (HR-XRD) data show that typical polycrystalline ZnO nanostructure layers have been deposited. Near-perfect stoichiometry of Zn and O atom vacancies has been observed from energy dispersion spectroscopy (EDS) spectrum. Photoluminescence (PL) spectra show strong peaks at UV and green regions. An increase in the stoichiometry of ZnO has been achieved with the oxygen gas flow during annealing indicating that deep-level defects represented by interstitial oxygen and antisite oxygen are gas pressure dependent. A single exciton peak with binding energy 60 meV has been observed at room temperature.

CaSi₂ with a Zintl phase was investigated for the synthesis of nanosheets due to its facile formation of Ca²⁺(Si^-)₂. The anionic Si^- is isoelectronic with V elements and forms anion partial lattices of corrugated layers like As. The Ca²⁺ planar layers are sandwiched between the anion layers. This CaSi₂ precursor was dispersed in a tetrabutylammonium hydroxide (TBA⁺OH^-), and the resulting solid was lamellar Si·TBA composite. Finally, simple heat treatment of the lamellar precursor at 950°C under vacuum leads to Si nanosheets. The Si nanosheets grown along [111] direction has lateral dimensions up to several hundreds of microns, and thickness of 20–70 nm. Photoluminescence measurements reveal that the present Si nanosheets have visible emission bands ranging from green to red.

Nano-ordered hybrid films of layered double hydroxide (LDH) nanosheets and two types of anionic dye molecules, i.e. tetrakis(4-carboxyphenyl)porphyrin (TCPP) and 1,3,6,8-pyrenetetrasulfonic acid (PTSA), were prepared by a layer-by-layer deposition (LBL) method. Photo-induced energy transfers (PET) between the PTSA and TCPP layers were investigated for two differently stacked structures of the TCPP/LDH/PTSA hybrid films, i.e. (a) PTSA/LDH multilayers independently stacked on the TCPP/LDH multilayers to form (TCPP/LDH)_n/(PTSA/LDH)_n and (b) TCPP/LDH and PTSA/LDH monolayers deposited alternately to form [(TCPP/LDH)/(PTSA/LDH)]_n hybrid films, which were both prepared by varying the successive and alternate stacking of the (TCPP/LDH) and (PTSA/LDH) unit layers. A Foerster type resonance energy transfer is observed in the present hybrid films, where the efficiency of PET was strongly affected by changing the distance between the TCPP and PTSA molecules in the (TCPP/LDH)₃/(PSS/LDH)_m/(PTSA/LDH)₃ hybrid films (m = 1−10) obtained by the insertion of the photochemically inert poly(styrenesulfonic acid) (PSS) and LDH hybrid layers, i.e. the insertion of (PSS/LDH)_m between the (TCPP/LDH)₃ and (PTSA/LDH)₃ layers.

A tetraanionic porphyrin and a tetracationic metallomacrocycle formed a layered two-dimensional nanosheet through multiple electrostatic interactions. X-ray crystallography revealed that the sheet is an ionic lattice composed of $\pi$-conjugated components

Large specific surface area porous g-C₃N₄ nanosheets were prepared by utilizing acetaldehyde-mediated melamine. The synthetic processes adopted two-step thermal treatments which are in N₂ and then in an air atmosphere. The introduced acetaldehyde made melamine condensation incompletely and generated body defects in g-C₃N₄ when heated in N₂. Further heating in air realized pores formation at sites of body defects, thus increase the specific surface area of g-C₃N₄. Notably, the introduction of acetaldehyde is beneficial to generate high concentration defects, which are active sites for thermal oxidative etching, and increase the yield of g-C₃N₄ by inhibiting the sublimation of melamine. The photocatalytic performance of obtained g-C₃N₄ was evaluated by the degradation of 2-propanol under visible light irradiation ($\lambda >420$nm). The porous g-C₃N₄ exhibits excellent photocatalytic performance than bulk g-C₃N₄. The addition of trace acetaldehyde significantly increased the specific surface area and enhanced photocatalytic activity, providing a new idea for the development of simple, low-cost and high active g-C₃N₄ photocatalyst.

Density functional theory (DFT) analyses were carried out to study electronic structures and magnetic properties of Mn- and Cu-doped GaNNS. To investigate the influence of transition metal atoms (TM) on magnetic properties, we substituted Ga atoms with Mn and Cu atoms in different concentrations. Investigation shows that TM leads to electronic structural reconstruction which changes their properties in this way, and plays a significant role in spin polarization. Although the pure nanosheet is a nonmagnetic semiconductor, the doped atoms induce magnetism in the structure. The band gap changes monotonically depending on the concentration of TM atoms. The observed good half-metal ferromagnetism GaNNS:Mn, allows them to be a potential candidate for use in spintronics. The local magnetic moment calculated from Mulliken analyses for the Mn atom is approximately 4.05 $\mu$B.

A variety of nanostructure bundles and arrays based on semiconducting metal silicides have been synthesized using abundant and non-toxic starting materials. Three types of fabrication techniques of the nanostructure bundles or arrays, including direct growth, template synthesis using natural nanostructured materials and template synthesis using artificially fabricated nanostructured materials are demonstrated. CrSi₂ nanowire bundles were directly grown by the exposure of Si substrates to CrCl₂ vapor at atmospheric pressure. A hexagonal MoSi₂ nanosheet, Mg₂Si/MgO composite nanowire and Mg₂Si nanowire bundles and MnSi_1.7 nanowire array were synthesized using a MoS₂ layered material, a SiO_x nanofiber bundle, a Si nanowire array, and a Si nanowire array as the templates, respectively. Additionally, the fabrication phenomenon and structural properties of the nanostructured semiconducting metal silicides were investigated. These reactions provided the low-cost and controllable synthetic techniques to synthesize large scale and one-dimensional semiconducting metal silicides for thermoelectric applications.

Two-dimensional nanosheets of lanthanum oxysulfates (La₂O₂SO₄) are prepared for the first time by a facile, effective molten salt synthesis route at a low temperature (400°C). Transmission electron microscopy (TEM) shows that the nanosheets are 100 nm to 200 nm thick and several micrometers in in-plane size. The intrinsic crystallography of the nanosheets is characterized by X-ray diffraction, high-resolution TEM, and selected area electron diffraction. The composition of the sample is studied by energy dispersive X-ray spectroscopy. The formation process of the nanosheets in molten salts is also investigated. The luminescence properties of the obtained La₂O₂SO₄ nanosheets are investigated by doping with Eu³⁺ at different concentrations. The nanosheets are found to exhibit good monochromaticity with high color saturation.