Studies on interstitial carbon doping from a Ti precursor in a hierarchical TiO2 nanostructured photoanode by a single step hydrothermal route

Carbon doping from a Ti precursor in TiO₂ synthesized by a hydrothermal method was studied. The structural, optical and morphological study of the deposited material was carried out using X-ray diffraction, UV-vis spectroscopy and scanning electron microscopy characterization techniques. The elemental composition of the TiO₂ deposited with different precursor concentrations was studied using X-ray photoelectron spectroscopy and electron dispersive X-ray spectroscopy. The amount of elemental carbon in the TiO₂ matrix is found to be increased as the Ti precursor concentration is increased, which strengthens the proposed idea of carbon doping via a Ti precursor.

Interstitial carbon doping is possible directly from a Ti precursor (titanium(iv) isopropoxide) without using any other carbon source.

Surfactant-free pH-assisted facile engineering of hierarchical rutile TiO2 nanostructures by a single step hydrothermal method for water splitting application

The structural appearance of TiO₂ nanostructures can be easily engineered by means of pH of the solvent solution.

Effects of Au loading on the enhancement of photoelectrochemical activities of the Au@ZnO nano-heteroarchitecture

The nano-heteroarchitecture of Au@ZnO evidencing the surface attachment without chemical reaction at the interface delivered enhanced PEC activities by facilitating the injection of hot electrons from the SP state into the conduction band of ZnO.

The effect of stoichiometry on the structural, thermal and electronic properties of thermally decomposed nickel oxide

A thermal decomposition route with different sintering temperatures was employed to prepare non-stoichiometric nickel oxide (Ni_1−δO) from Ni(NO₃)₂·6H₂O as a precursor. The non-stoichiometry of samples was then studied chemically by iodometric titration, wherein the concentration of Ni³⁺ determined by chemical analysis, which is increasing with increasing excess of oxygen or reducing the sintering temperature from the stoichiometric NiO; it decreases as sintering temperature increases. These results were corroborated by the excess oxygen obtained from the thermo-gravimetric analysis (TGA). X-ray diffraction (XRD) and Fourier transformed infrared (FTIR) techniques indicate the crystalline nature, Ni–O bond vibrations and cubic structural phase of Ni_1−δO. The change in oxidation state of nickel from Ni³⁺ to Ni²⁺ were seen in the X-ray photoelectron spectroscopy (XPS) analysis and found to be completely saturated in Ni²⁺ as the sintering temperature reaches 700 °C. This analysis accounts for the implication of non-stoichiometric on the magnetization data, which indicate a shift in antiferromagnetic ordering temperature (T_N) due to associated increased magnetic disorder. A sharp transition in the specific heat capacity at T_N and a shift towards lower temperature are also evidenced with respect to the non-stoichiometry of the system.

A thermal decomposition route with different sintering temperatures was employed to prepare non-stoichiometric nickel oxide (Ni_1−δO) from Ni(NO₃)₂·6H₂O as a precursor.

Nano-Heteroarchitectures of Two-Dimensional MoS2@ One-Dimensional Brookite TiO2 Nanorods: Prominent Electron Emitters for Displays

We report comparative field electron emission (FE) studies on a large-area array of two-dimensional MoS₂-coated @ one-dimensional (1D) brookite (β) TiO₂ nanorods synthesized on Si substrate utilizing hot-filament metal vapor deposition technique and pulsed laser deposition method, independently. The 10 nm wide and 760 nm long 1D β-TiO₂ nanorods were coated with MoS₂ layers of thickness ∼4 (±2), 20 (±3), and 40 (±3) nm. The turn-on field (E _on) of 2.5 V/μm required to a draw current density of 10 μA/cm² observed for MoS₂-coated 1D β-TiO₂ nanorods emitters is significantly lower than that of doped/undoped 1D TiO₂ nanostructures, pristine MoS₂ sheets, MoS₂@SnO₂, and TiO₂@MoS₂ heterostructure-based field emitters. The orthodoxy test confirms the viability of the field emission measurements, specifically field enhancement factor (β_FE) of the MoS₂@TiO₂/Si emitters. The enhanced FE behavior of the MoS₂@TiO₂/Si emitter can be attributed to the modulation of the electronic properties due to heterostructure and interface effects, in addition to the high aspect ratio of the vertically aligned TiO₂ nanorods. Furthermore, these MoS₂@TiO₂/Si emitters exhibit better emission stability. The results obtained herein suggest that the heteroarchitecture of MoS₂@β-TiO₂ nanorods holds the potential for their applications in FE-based nanoelectronic devices such as displays and electron sources. Moreover, the strategy employed here to enhance the FE behavior via rational design of heteroarchitecture structure can be further extended to improve other functionalities of various nanomaterials.

Terahertz spin-wave waveguides and optical magnonics in one-dimensional NiO nanorods

The two-magnon (2M) spin waves with a magnon frequency of 43 THz, generated by a polarized laser, were first observed in one-dimensional (1D) NiO nanorods. The 1D NiO nanorods of ∼700 nm length, which have perfectly in-plane antiferromagnetic spins lying on the (200) and (100) faces, are the smallest spin-wave waveguides. Due to the magneto-optical Faraday effect (MOFE), the significant change in the Faraday intensity can show the 2M information in the NiO nanorods. There are only two 2M-on and 2M-off states at various applied alternating-current magnetic fields and laser-incident angles, which make the 1D NiO nanorods excellent optical nanomagnonics.

Promising field electron emission performance of vertically aligned one dimensional (1D) brookite (β) TiO2nanorods

The vertically aligned and uniformly dispersed β-TiO₂nanorods injected electrons direct toward emission sites, and prominently contributed to the low turn-on field of 3.9 V μm⁻¹at a current density of 10 μA and also enhance the emission stability.

A microwave molecular solution based approach towards high-κ-tantalum(v)oxide nanoparticles: synthesis, dielectric properties and electron paramagnetic resonance spectroscopic studies of their defect chemistry

Transparent and dense dielectric Ta₂O₅ thin films are accessible via a solution based molecular approach.

Photoluminescence mechanisms of metallic Zn nanospheres, semiconducting ZnO nanoballoons, and metal-semiconductor Zn/ZnO nanospheres

We utilized a thermal radiation method to synthesize semiconducting hollow ZnO nanoballoons and metal-semiconductor concentric solid Zn/ZnO nanospheres from metallic solid Zn nanospheres. The chemical properties, crystalline structures, and photoluminescence mechanisms for the metallic solid Zn nanospheres, semiconducting hollow ZnO nanoballoons, and metal-semiconductor concentric solid Zn/ZnO nanospheres are presented. The PL emissions of the metallic Zn solid nanospheres are mainly dependent on the electron transitions between the Fermi level (E(F)) and the 3d band, while those of the semiconducting hollow ZnO nanoballoons are ascribed to the near band edge (NBE) and deep level electron transitions. The PL emissions of the metal-semiconductor concentric solid Zn/ZnO nanospheres are attributed to the electron transitions across the metal-semiconductor junction, from the E(F) to the valence and 3d bands, and from the interface states to the valence band. All three nanostructures are excellent room-temperature light emitters.

An efficient methodology for measurement of the average electrical properties of single one-dimensional NiO nanorods

We utilized a metal tantalum (Ta) ball-probe to measure the electrical properties of vertical-aligned one-dimensional (1D) nickel-oxide (NiO) nanorods. The 1D NiO nanorods (on average, ~105 nm wide and ~700 nm long) are synthesized using the hot-filament metal-oxide vapor deposition (HFMOVD) technique, and they are cubic phased and have a wide bandgap of 3.68 eV. When the 1D NiO nanorods are arranged in a large-area array in ohmic-contact with the Ta ball-probe, they acted as many parallel resistors. By means of a rigorous calculation, we can easily acquire the average resistance RNR and resistivity ρNR of a single NiO nanorod, which were approximately 3.1 × 10(13) Ω and 4.9 × 10(7) Ω.cm, respectively.

Two-dimensional single-crystalline Zn hexagonal nanoplates: size-controllable synthesis and X-ray diffraction study

We synthesized two-dimensional (2D) Zn hexagonal nanoplates using the thermal metal-vapor deposition technique. An increase and decrease in the surface area and thickness of the 2D Zn hexagonal nanoplates were shown with elevated annealing temperatures, indicating their sizes to be controlled using the annealing treatment. X-Ray diffractometry (XRD) studies revealed the crystalline nature of the 2D Zn hexagonal nanoplates and the diffraction intensity of the (002) lattice plane, which increased parabolically with elevated annealing temperatures.