Ion-doped mesoporous bioactive glass: preparation, characterization, and applications using the spray pyrolysis method

Bioactive glasses (BAG) are one type of biomaterial that is used in dentistry and orthopedics to repair or replace damaged bone. The spray pyrolysis process is low-cost and one of the most common ways for producing porous films and films with high-density packing and particle homogeneity.

Influence of the Distance Between Nozzle and Substrate on Structural, Photoluminescence, and Detector Characteristics of p-NiO/n-Si Hetero-Junction Deposited by Spray Pyrolysis Method

In the present investigation, p-NiO has been deposited on n-Si (100) substrate by the spray pyrolysis method. The effect of the distance between the substrate and the nozzle on the structural, photoluminescence, and detection properties has been well inspected. XRD analysis proved the polycrystalline system with a cubic structure for NiO. The elemental analysis confirmed the existence of Ni, O, and Si materials without any impurities. The FESEM analysis showed nano and micro particles distributed on the Si layer, the micro particles have porous like structures which play a significant role as photons guider. The photoluminescence measurement depicted three main peaks at the UV and visible regions of the electromagnetic spectrum which are related to near band edge emission and defects within the crystal, respectively. I-V characteristics revealed good conductivity under UV illumination, and the highest current was recorded by a sample when the distance between the nozzle and the substrate is 25 cm. The responsivity elucidated a high value at UV region with 6.5 mA/W, and the current-time properties demonstrated good reproducibility, high stability and photoresponse, and rapid response and recovery times of 0.375 and 0.791 s, respectively at a lower bias voltage of 1.5 Volt under UV photons source.

Pyrolytic Oil Yield from Waste Plastic in Quezon City, Philippines: Optimization Using Response Surface Methodology

Plastics play an essential role in packaging materials because of their durability to different environmental conditions. With its importance in the community lies the problem with waste disposal. Plastic is a non-biodegradable material, making it a big problem, especially when thrown in dumpsites. In solving the plastic problem, one efficient way to reduce its volume is through thermal processing such as pyrolysis. This study used the pyrolysis method to recover energy from plastic waste. Liquid oil from plastic was comparable to regular fuel used in powering engines. Before the pyrolysis process, a 3k factorial Box-Behnken Design was used in determining the number of experiments to be used. The output oil yield in each pyrolysis runs was optimized in different parameters, such as temperature, residence time, and particle size using response surface methodology to determine the optimum oil yield. Between polyethylene (PE), mixed plastic, and polystyrene (PS), PS produced its highest oil yield of 90 %. In comparison, mixed plastic produced only its highest oil yield of 45 % in 500 ºC temperature, 120 min residence time, and 3 cm particle size. The produced quadratic mathematical models in PE, mixed, and PS plastic were significant in which the p-values were less than 0.05. Using mathematical models, the optimum oil yield for PE (467.68 ºC, 120 min residence time, 2 cm particle size), mixed (500 ºC, 120 min residence time, 2.75 cm particle size) and PS plastic (500 ºC, 120 min residence time, 2 cm particle size) were 75.39 %, 46.74 %, and 91.38 %, respectively

The Importance of Molybdenum(IV) Active Sites in Promoting Electrochemical Reduction of N2 to NH3 with MoFe Bimetallic Catalysts

To overcome the low faradaic efficiency (FE) of single Mo or Fe based electrocatalysts in nitrogen reduction reactions (NRR) due to the competition from the hydrogen evolution reaction (HER), a series of bimetallic MoFe compound catalysts were prepared under an NH3 atmosphere through a facile precipitation-pyrolysis method. The formed tetravalent Mo was found to be capable of inducing better electronic interactions between the surface nitrogen species and the Fe metal groups, thus improving the FE. It was demonstrated that the prepared ternary MoFe-N catalyst exhibited a remarkable FE of 33.26 % and a high NH3 yield of 33.31 μg h-1 mg-1cat. for NRR, which was believed to have been caused by an obvious change in the valence of Mo that resulted in a lower HER activity. X-ray photoelectron spectroscopy analysis further revealed that thermal processing under an NH3 atmosphere formed the Mo(IV) active sites in Mo-N bond, which led to a significant suppression in HER activity. Finally, through the study of the surface hydrogenation mechanism, it was concluded that the synergistic effect of the adsorbed H* and Mo active sites was the main reason for the improved performance of NRR.

Investigation of the Temperature on the Thin Layers of Cobalt Oxide Produced by the Spray Pyrolysis Method Using a Solar Oven

Thin films of cobalt oxide (Co3O4) were prepared on glass substrates by the spray pyrolysis method using a solar concentrator (oven) manufactured in our laboratory. We used different processing temperatures (300° C, 350° C and 400° C). The structural, optical and electrical properties of the different samples were analyzed by X-ray diffraction (XRD), UV-Visible spectroscopy and the Hall effect measurement system. X-ray diffraction observations revealed that cubic crystals are created in all films produced, and the film structure is that of a single phase created with preferential orientation along the (311) axis in films at low temperatures, and the axis (111) for high temperatures. The grain sizes of our products vary between (22.62nm and 66.19nm), depending on the processing temperature. The optical band gap of the crystals obtained was measured. The results of the optical forbidden bands of the crystals obtained, indicated two bands of the values for each element (Eg1 and Eg2). We observed that the values of the effective optical forbidden bands increase by 2.547eV and 3.0731eV with the increase in the production temperature., In addition the film produced experiences a decrease in the Urbach parameters which vary between 162.20meV and 360.81meV depending on the increase in production temperatures. Finally, the films produced have electrical conductivity values of (1.090 [(Ω.cm)−1] to 1.853 [(Ω.cm)−1] and electrical resistivity values of 1.431 (Ω.cm) at 1.853 (Ω.cm), depending on the variation in the production temperature.

Preparation of hollow spherical particles of ferrite strontium SrFe₁₂O₁₉ by spray-pyrolysis

The article presents the synthesis of hollow nanostructured microspheres of ferrite strontium by spray-pyrolysis. The phase composition, morphology, dispersion of the microspheres obtained and the effect of synthesis parameters to the morphology and the dispersion of the material obtained are investigated. It has been established that in the process of synthesis by spray-pyrolysis method, hollow nanostructured microspheres are formed with dimensions in the range of 0,5‒10,0 μm, the thickness of the microspheres of the microspheres is about 100 nm. Microspheres consist of particles of 10‒20 nm. Ill. 4. Ref. 12. Tab. 1.