Mohamed S. Hamdy

Facile hydrothermal synthesis and characterization of cesium-doped PbI2 nanostructures for optoelectronic, radiation detection and photocatalytic applications

AbstractLow-temperature hydrothermal-assisted synthesis of pure and cesium (Cs) (1, 3, 5, 7 and 10xa0wt%) doped lead iodide (PbI2) nanorods and nanosheets have been achieved successfully for the first time. The structural and vibrational studies confirm the formation of a 2H-polytypic PbI2 predominantly. Scanning electron microscope analysis confirms the formation of well-aligned nanorods of average size ~xa0100xa0nm at low concentration and nanosheets of average thicknesses in the range of ~xa020–40xa0nm at higher concentrations of Cs doping. The presence of Cs doping was confirmed by energy dispersive X-ray study. Ultra-violet-visible absorbance spectra were recorded, and energy gap was calculated in the range of 3.33 to 3.45xa0eV for pure and Cs-doped PbI2 nanostructures which is higher than the bulk value (i.e., ~xa02.27xa0eV) due to quantum confinement effect. Dielectric constant, loss, and AC conductivity studies have been done. Enhancement in Gamma linear absorption coefficient due to Cs doping confirms the suitability of prepared nanostructures for radiation detection applications. Furthermore, the photocatalytic performance of the synthesized nanostructures was evaluated in the decolorization of methyl green (MG) and methyl orange (MO) under the illumination of visible light (λxa0>xa0420xa0nm). The observed photocatalytic activity for 5 and 7xa0wt% Cs-doped PbI2 was observed to be more than pure PbI2 and also >xa010 times higher than the commercially available photocatalysts. The results suggest that the prepared nanostructures are highly applicable in optoelectronic, radiation detection and many other applications.n Graphical abstractᅟ

New catalyst with multiple active sites for selective hydrogenolysis of cellulose to ethylene glycol

Three different metals were successfully incorporated into the mesoporous siliceous material, TUD-1, for the first time. One-pot synthesis was applied to incorporate isolated Al3+, nanoparticles of WO3, and nanoparticles of metallic Ni with different loadings into TUD-1. The prepared materials were characterized by means of elemental analysis, XRD, N2 physisorption, NH3-TPD, SEM, EDX and TEM. Characterization data confirmed the incorporation of isolated Al3+ ions in the framework of TUD-1, in addition to metallic Ni (3–5 nm) and WO3 (10–15 nm) nanoparticles inside the pores of TUD-1 matrix. Moreover, extra-framework WO3 particles (0.5–1 μm) were also detected. The catalytic activity of the prepared samples was evaluated in the selective hydrogenolysis of cellulose into ethylene glycol at 503 K under 4 MPa of H2 pressure in the presence of water as a solvent. The catalyst with the multiple active sites exhibited the highest cellulose conversion (100%) after reaction for 90 min and the ethylene glycol yield was 76%.

Photocatalytic decomposition of cortisone acetate in aqueous solution

The photocatalytic decomposition of cortisone 21-acetate (CA), a model compound for the commonly used steroid, cortisone, was studied. CA was photocatalytically decomposed in a slurry reactor with the initial rates between 0.11 and 0.46 mg L(-1)min(-1) at 10 mg L(-1) concentration, using the following heterogeneous photocatalysts in decreasing order of their catalytic activity: ZnO>Evonik TiO2 P25>Hombikat TiO2>WO3. Due to the lack of ZnO stability in aqueous solutions, TiO2 P25 was chosen for further experiments. The decomposition reaction was found to be pseudo-first order and the rate constant decreased as a function of increasing initial CA concentration. Changing the initial pH of the CA solution did not affect the reaction rate significantly. The decomposition reaction in the presence of the oxidizing sacrificial agent sodium persulfate showed an observed decomposition rate constant of 0.004 min(-1), lower than that obtained for TiO2 P25 (0.040 min(-1)). The highest photocatalytic degradation rate constant was obtained combining both TiO2 P25 and S2O8(2-) (0.071 min(-1)) showing a synergistic effect. No reactive intermediates were detected using LC-MS showing fast photocatalytic decomposition kinetics of CA.

A Novel Method to Improve the Anticancer Activity of Natural-Based Hydroxyapatite against the Liver Cancer Cell Line HepG2 Using Mesoporous Magnesia as a Micro-Carrier

Micro-carriers are the best known vehicles to transport different kinds of drugs to achieve high impact. In this study, mesoporous magnesium oxide has been harnessed as a micro-carrier to encapsulate the anticancer candidate drug natural-based cubic hydroxyapatite (HAP). HAP@MgO composites with different HAP loading (0–60 wt %), were prepared by a hydrothermal treatment method using triethanol amine as a template. The characterization of the prepared composites were achieved by using XRD, Raman spectroscopy, FTIR and SEM. Characterization data confirm the formation of sphere-like structures of MgO containing HAP particles. It was observed that the size of the spheres increased with HAP loading up to 40 wt %, then collapsed. Furthermore, the anticancer property of the prepared composites was evaluated against the HepG2 liver cancer cell line. The HAP@MgO composites exhibited higher activity than neat MgO or HAP. The 20 wt % of HAP was the optimum loading to control cell proliferation by inducing apoptosis. Apoptosis was determined by typical apoptotic bodies produced by the cell membrane.

Solvent-free hydrogenation of cyclohexene over Rh-TUD-1 at ambient conditions

Rhodium nanoparticles (≈3–5 nm) were incorporated into the 3D mesoporous TUD-1 material by using sol–gel technique. The prepared catalyst shows high activity in the liquid phase conversion of cyclohexene to cyclohexane at room temperature (298 K), 1 atm H2 pressure, and under solvent-free conditions. Rhodium nanoparticles exhibited high stability, reusability and negligible leaching.