A facile in situ approach to fabricate N,S-TiO2/g-C3N4 nanocomposite with excellent activity for visible light induced water splitting for hydrogen evolution

The efficient charge separation, small crystallite size and enhanced specific surface area in N,S-TiO2/g-C3N4 nanocomposites make the system pivotal and unique for hydrogen evolution.

An Overview on the Photocatalytic Activity of Nano-Doped-TiO2 in the Degradation of Organic Pollutants

This paper aims to review and summarize the recent works on the photocatalytic degradation of various organic pollutants in the presence of nano-doped-TiO2 photocatalysts. In this regard, three main aspects are examined: (a) the presence of various dopants (metal dopants, nonmetal dopants, halogen dopants, metalloid dopants, and codopants) in the formation of nano-doped-TiO2 photocatalysts, (b) the effect of the presence of dopants on the photocatalytic degradation of organic pollutants, and (c) the effects of various operating parameters on the photocatalytic degradation of organic pollutants in the presence of nano-doped-TiO2 photocatalysts. Reports resulted suggest that the formation of a high percentage of the anatase phase, small crystallite size, and high specific surface area of the nano-doped-TiO2 photocatalysts depends on the presence of various dopants in the photocatalysts. The majority of the dopants have the potential to improve the photocatalytic efficiency of nano-doped-TiO2 in the degradation of organic pollutants. The photocatalytic degradation of organic compounds depends on the calcination temperature of the prepared doped TiO2, initial reactant concentration, dosage of doped TiO2, and dopant doping concentration.

Thermodynamic stability of tetragonal zirconia nanocrystallites

The thermodynamic stability of tetragonal (t-) ZrO2 nanocrystallites below the bulk stability temperature 1200 °C was studied through specially synthesized crystallites that exhibited an extremely slow coarsening rate. The nanocrystallites were mechanically transformed to the monoclinic (m-) structure, and, because the crystallite size was kept below approximately 20 nm, the t-structure was completely recovered solely by thermal treatments between 900 and 1100 °C. These results gave strong evidence to the notion that, for sufficiently small crystallite size, nanocrystalline t-ZrO2 is not just kinetically metastable but can be truly thermodynamically more stable than the mpolymorph in air below 1200 °C.

A Full-Trace Database for the Analysis of Clay Minerals

A file of digitized diffraction traces for clay minerals has been developed as a test for the usefulness of such traces in the analysis of clays and clay deposits. The kaolin, smectite, mica clay and chlorite groups are represented by patterns of the most common mineral species in the small crystallite size which is typical of their natural occurrences. Patterns are included for the oriented sample and for glycolated and heated samples when appropriate. This database may form a nucleus for an extensive collection of clay mineral traces in the same manner as the early Powder Diffraction File did for the modern PDE.

Structural Characterization of Nanocrystalline Mo and W Carbide and Nitride Catalysts Produced by Co2 Laser Pyrolysis

ABSTRACTUsing both XRD and HRTEM lattice imaging, we have shown that CO2 laser pyrolysis (LP) produces nanoscale transition metal carbide and nitride catalysts, including cubic Mo2C, Mo2N, and W2N, which possess highly crystalline structures in their as-synthesized form In contrast, LP-produced W2C in its hexagonal phase is disordered. Clear lattice expansion, induced by the small crystallite size of the nanoparticles has been observed for LP-produced Mo2C particles, which have a typical crystallite size of 2 nm. No carbon coating was observed in HRTEM for LP-produced Mo2C particles. Furthermore, Mo=N and Mo=C bonding in Mo2N and Mo2C, respectively, were identified by an XPS measurement, which also reveals the presence of a thin oxide layer formed on the particle surface during the passivation process. Finally, the average crystallite sizes determined from HRTEM and XRD are in good agreement, indicating that the line broadening observed in XRD is due to the small crystallite size of the nanoparticles.