Jamal Nasir

One of the most significant global challenges for humans is environmental pollution. The technology to control this problem is the utilization of semiconductors as photocatalysts. In the current study, iron-doped titania nanotubes (Fe/TiNTs) with increased photocatalytic effect were synthesized via a modified hydrothermal method. The products were characterized by X-ray powder diffraction, scanning electron microscopy, transmission electron microscopy (TEM), gas adsorption, electron spin resonance (ESR) and UV–Vis diffuse reflectance spectroscopy (DRS). TEM results indicated that Fe/TiNTs have a tubular and uniform structure with an average outer diameter of 23–48 nm and length of 10–15 µm. ESR and DRS revealed that Fe³⁺ ions were successfully introduced into the TiNT structure by replacing Ti⁴⁺ ions. An enhanced light absorption in the range of 400–600 nm additionally indicated successful doping. The band gap was narrowed as iron wt% was increased. The photocatalytic activity was evaluated by the degradation of methyl orange (MO) in the presence of Fe/TiNTs and TiTNs by monitoring the degradation of MO under UV light irradiation. An acceleration on the hydration of Portland cement was observed in the presence of 2.0 wt% Fe/TiNTs. Fe/TiNTs can be used as a nanomaterial in cement-based building materials to provide self-cleaning properties to the surface of concrete even in indoor environments.

Powder X-ray diffraction, 27Al solid-state NMR and TEM were used to study the structure and phase transformations in a series of transition alumina materials with BET surface areas ranging from 220 to 30 m2/g produced by gas-to-particle flame method. During the short-lived synthesis, highly disordered γ-alumina progressively transforms into a mixture of δ and θ-alumina. For the well-crystallized mixture of δ and θ-alumina, high resolution and high S/N powder XRD pattern features a large number of superstructure reflections along with the commonly observed diffuse reflections. 27Al MQMAS NMR provides a total of 8 crystallographic sites with an unusually high resolution in the tetrahedral region, with 4 distinct AlO 4 sites pertaining to the δ phase alone. We propose here based on data acquired on high-quality δ and θ-alumina that the bulk structures of both phases must be ordered.

A Guinier camera equipped with an imaging plate is used to investigate and eliminate the sources of instrumental errors affecting the quality of the obtained scanned Guinier data. A program with a graphical user interface is presented which converts the data of the scanned images into different standard file formats for powder X-ray patterns containing intensities, their standard deviations and the diffraction angles. The program also allows for manual and automatic correction of the 2θ scale against a known reference material. It is shown using LaB₆ that the exported X-ray diffraction patterns provide a 2θ scale reproducible enough to allow for averaging diffractograms obtained from different exposures of the imaging plate for the same sample. As shown on a mixture of NaCl and sodalite, the quality of the produced data is sufficient for Rietveld refinement. The software including source code is made available under a free software license.

Ce_1−xLn_xO_2−x/2 nanocrystals prepared mechanochemically from CeCl₃, LnCl₃, and Na₂CO₃ show enhanced haloperoxidase activity. ESR and IR spectroscopy revealed the Ln³⁺ distribution in the CeO₂ host and the presence of Ce³⁺ and O₂⁻ surface species.

The binary lead fluoride Pb₃F₈ was synthesized by the reaction of anhydrous HF with Pb₃O₄ or by the reaction of BrF₃ with PbF₂. The compound was characterized by single‐crystal and powder X‐ray diffraction, IR, Raman, and solid‐state MAS ¹⁹F NMR spectroscopy, as well as thermogravimetric analysis, XP and near‐edge X‐ray absorption fine structure (NEXAFS) spectroscopy. Solid‐state quantum‐chemical calculations are provided for the vibrational analyses and band assignments. The electronic band structure offers an inside view of the mixed valence compound.