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6. Enhancement in structural, morphological, and optical properties of copper oxide for optoelectronic device applications

Author

Saleem Shahroz, Jabbar Abdullah Hasan, Jameel Muhammad Hasnain, Rehman Azka, Kareem Zahraa Hashim, Abbas Ali Hashim, Ghaffar Zunaira, Razzaq Saba Abdul, Pashameah Rami Adel, Alzahrani Eman, Ng Eng-Poh, and Sapuan Salit Mohd

Subjects
copper oxide, xrd, raman, sem, ftir, uv, optoelectronic devices, Technology, Chemical technology, TP1-1185, Physical and theoretical chemistry, QD450-801
Abstract

In this study, copper oxide (CuO) specimens were successfully prepared by the hydrothermal process at altered calcination temperatures; 350, 450, and 550°C. The synthesized samples were analyzed through X-ray powder diffraction (XRD), scanning electron microscope (SEM), Raman, Fourier-transform infrared spectroscopy (FTIR), and UV-Vis spectroscopy to analyze the impact of calcination temperature on the structural, morphological, vibration spectra, functional group, and optical properties of CuO for optoelectronic device applications. XRD confirms the pure single-phase monoclinic structure of synthesized samples with no impurity phases and has good crystallinity with the development in calcination temperature. The average crystalline size, lattice constant, and porosity were found in the range of 3.98–5.06 nm; a = 3.4357 Å, b = 3.9902 Å, c = 4.8977 Å – a = 3.0573 Å, b = 3.9573 Å, c = 4.6892 Å; and 3.37–1.03%, respectively. SEM exhibited a variation in morphology by increasing calcination temperature. Raman spectra revealed that the CuO sample calcinated at 550°C with a stone-like shape having a large grain size of 3.25 μm exhibited that Raman peak intensity and the multiphonon band became stronger and sharper and exhibited higher intensity compared to the samples calcinated at 350 and 450°C. FTIR spectra confirmed that these synthesized specimens exhibited the peaks associated with the typical stretching vibrations of the Cu–O bond between 400 and 500 cm−1 exhibiting the formation of CuO. The energy bandgap was slightly reduced from 1.61 to 1.43 eV with the increase in the calcination temperature. The optical studies revealed that the calcination temperature of 550°C improves the optical properties of CuO by tuning its optical bandgap. The modified structural, morphological, and optical characteristics of the prepared CuO samples make them an appropriate candidate for optoelectronic device applications.

Published
2022
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26. The effect of Isoprenyl Ether polymer molecular structure on cementitious composites

Author

Cheah Chee Ban, Ng Peck Gee, Tiong Ling Ling, Ng Eng Poh, and Oo Chuan Wei

Subjects
t-peg, marsh cone funnel test, molecular structure, flow retention, cementation property, Mechanical engineering and machinery, TJ1-1570, Mechanics of engineering. Applied mechanics, TA349-359
Abstract

In order to minimize the rapid flow loss issue from the hot weather or during lengthy periods and long-distance transport, the synthesis of the isoprenyl oxy polyethylene ether (T-PEG) was introduced. However, there were scarce amount of reported literature on the influence of main and side chain densities on the fresh and hardened properties of concrete containing T-PEG polymers. This study was conducted to investigate fresh and mechanical properties of cementitious composites containing T-PEG polymers with different main and side chain densities. These T-PEG polymers were comprised of the density ratio of side chain to main chain of 1:1, 1:1.5, 1:2, 1:2.5 and 1:3.5, respectively. The laboratory tests conducted were marsh cone funnel test, standard consistency, flow retention, flexural strength and compressive strength test. The results obtained showed that the increased density ratio of side chain to main chain of T-PEG improves the fluidity of the cement paste and the flow retention ability of the cement mortar. Consequently, the mortar with T2 polymer proved a better performance on mechanical strength tests. In conclusion, the increasing main to side chain densities ratio of T-PEG polymer imposes a significant influence on the fresh and hardened properties of the concrete material produced.

Published
2020
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35. Direct evidence of time-dependent crystallization evolution of SAPO-34 and SAPO-20 zeolites directed by trimethylbenzylammonium hydroxide for microwave-assisted ethanolysis of furfuryl alcohol.

Author

Wang, Guanchen, AlMasoud, Najla, Alomar, Taghrid S., Azman, Yasmin Nadhirah, Maireles-Torres, Pedro, Chia, Stephen, Juan, Joon Ching, Ling, Tau Chuan, El-Bahy, Zeinhom M., and Ng, Eng-Poh

Subjects
FURFURYL alcohol, CRYSTALLIZATION, ZEOLITES, CATALYTIC activity, MOLECULAR sieves, HYDROGELS
Abstract

Time-dependent crystallization evolution for synthesizing SAPO34 and SAPO-20 zeolites from a very active hydrogel is followed and reported where the XRD, FTIR, TGA/DTG, SEM/EDX, N2 adsorption–desorption and TPD-NH3 techniques are used. During the crystallization process, the hydrophobic trimethylbenzylammonium cation (BTMA+) has shown its ability as an effective structure-directing and pore filling agent. The resulting pure SAPO-34 and SAPO-20 show high crystallinity, where SAPO-34 exhibits higher porosity (393 m2 g−1, 0.24 cm3 g−1) and acidity (1.20 mmol g−1) than SAPO-20 (29 m2 g−1, 0.16 cm3 g−1, 0.02 mmol g−1), and these features are highly beneficial in the microwave-assisted ethanolysis of furfuryl alcohol. SAPO-34 shows outstanding catalytic activity (100% conversion, 72.5 ± 0.3% yield of ethyl levulinate) and its performance is much superior to that of SAPO-20 and other classical catalysts thanks to its medium pore size that induces molecular sieving effect. The spent SAPO-34 catalyst has high recyclability with stable activity, making it a superior and cost-effective catalyst for various selective petrochemical reactions. [ABSTRACT FROM AUTHOR]

Published
2024
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