Preparation and characterization of ZnO/ZnAl₂O₄-mixed metal oxides for dye-sensitized photodetector using Zn/Al-layered double hydroxide as precursor

In this article, a simple new technique has been developed for the preparation of ZnO/ZnAl₂O₄-mixed metal oxide (MMO) as anode materials for visible light dye-sensitized (DS) photodetector using Zn/Al-layered double hydroxide (LDH) as precursor. Subsequently, a detailed correlation between the structural properties of the prepared samples and the photo-responsive behavior of the fabricated DS photodetectors was elucidated. Specifically, it is evidenced that a high surface area of the prepared mesoporous MMO anode materials exhibit excellent dye absorptivity and thus facilitate free electron transfer and increase the photocurrent in the fabricated DS photodetector. A significant bathochromic shift was observed in the optical energy of the prepared MMO samples under the increment of molar ratio, providing a short electron transfer pathway in the optimized Z7A DS photodetector, which in turn demonstrated photo-responsivity and photo-detectivity of 6 mA/W and 1.7 × 10⁺¹⁰ Jones, respectively. This work presents an alternative approach for the design of an eco-friendly MMO-based DS photodetector

Confinement Diet, Physical Activity and Well-Being of Mothers with a Preterm Infant: A qualitative study

The confinement period is part of the Asian culture after giving birth. However, it is not fully understood how this practice affects women's health. This study aims to explore confinement diet and physical activity that may influence the psychosocial well-being of mothers. A focus group discussion was conducted on 22 Malay mothers with infants delivered prematurely. Data were analysed thematically. Four main themes were derived from the analysis; 1) healthy diet, 2) food restriction, 3) fitness and strength 4) barriers. Mothers believe that confinement practices are beneficial to their heath. Therefore, emphasizing on healthy lifestyle during the confinement period is necessary. Keywords: breastfeeding; confinement diet; postpartum mothers; well-being eISSN: 2398-4287 © 2022. The Authors. Published for AMER ABRA cE-Bs by e-International Publishing House, Ltd., UK. This is an open access article under the CC BYNC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/). Peer–review under responsibility of AMER (Association of Malaysian Environment-Behaviour Researchers), ABRA (Association of Behavioural Researchers on Asians/Africans/Arabians) and cE-Bs (Centre for Environment-Behaviour Studies), Faculty of Architecture, Planning & Surveying, Universiti Teknologi MARA, Malaysia. DOI: https://doi.org/10.21834/ebpj.v7i20.333

Theoretical Power Output of Thermoelectric Power Generator based on Metal Oxide Semiconductor

Optimizing the structure and material combination of thermoelectric power generators (TEGs) is essential to their efficiency. In order to develop an efficient TEG based on an oxide semiconductor, we theoretically simulated the power output of a TEG based on potential oxide semiconductors (ZnO, TiO2, and CuO) combined with electrode materials (Au, Ag, Cu, graphene, graphite, ITO, IZO, and AZO), and determined the influence of this material combination on the TEG’s power output. In this study, the power output was evaluated from simulated heat distribution and output voltage of a single leg and thermopiles using a simulator. The combination of ZnO and graphene showed the highest power output. This is likely due to the high thermal conductivity of graphene which allowed a high temperature difference in the ZnO. Moreover, the power output increased with decreasing electrode thickness, which allowed high output voltage to be generated by the thermoelectric material. The power density of the TEG consisting of several thermopiles based on ZnO and graphene materials was 29 mW/cm2, which was comparable with that of the\ud reported TEG consisting of Te-based materials. Thus, a TEG based on oxide semiconductor materials could be developed to reduce the use of harmful thermoelectric materials

The role of electrolyte fluidity on the power generation characteristics of thermally driven electrochemical cells

Thermally driven electrochemical cells (thermocells) are able to convert thermal gradient applied across redox electrolyte into electricity. The performance of the thermocells heavily depends on the magnitude and integrity of the applied thermal gradient. Herein, we study the iodide/triiodide (I–/I3 –) based 1-Ethyl-3-methyl-imidazolium Ethylsulfate ([EMIM][EtSO4]) solutions in a thermocell. In order to comprehend the role of fluidity of the electrolyte, we prepared set of solutions by diluting [EMIM][EtSO4] with 0.002, 0.004, and 0.010 mol of Acetonitrile (ACN). We realized a significant improvement in ionic conductivity (σ) and electrochemical Seebeck (Se) of diluted electrolytes as compared to base [EMIM][EtSO4] owing to the solvent organization. However, the infra-red thermography indicated faster heat flow in ACN-diluted-[EMIM] [EtSO4] as compared to the base [EMIM][EtSO4]. Therefore, the maximum power density of base [EMIM][EtSO4] (i.e. 118.5 μW.m-2) is 3 times higher than the ACN-diluted-[EMIM][EtSO4] (i.e. 36.1 μW.m-2) because of the lower thermal conductivity. Hence this paper illustrates the compromise between the fast mass/flow transfer due to fluidity (of diluted samples) and the low thermal conductivity (of the pure [EMIM][EtSO4])

Photophysical and Electrochemical Studies of Multinuclear Complexes of Iron(II) with Acetate and Extended Conjugated N-Donor Ligands

A dimeric iron(II) complex, trans-[Fe2(CH3COO)4(L1)2] (1), and a trinuclear iron(II) complex, [Fe3(CH3COO)4(H2O)4(L2)] (2), were studied as potential dye-sensitised solar cell materials. The structures of both complexes were deduced by a combination of instrumental analyses and molecular modelling. Variable-temperature magnetic susceptibility data suggested that 1 was made up of 56.8% high-spin (HS) and 43.2% low-spin (LS) Fe(II) atoms at 294 K and has a moderate antiferromagnetic interaction (J = −81.2 cm−1) between the two Fe(II) centres, while 2 was made up of 27.7% HS and 72.3% LS Fe(II) atoms at 300 K. The optical band gaps (Eo) for 1 were 1.9 eV (from absorption spectrum) and 2.2 eV (from fluorescence spectrum), electrochemical bandgap (Ee) was 0.83 eV, excited state lifetime (τ) was 0.67 ns, and formal redox potential (E′(FeIII/FeII)) was +0.63 V. The corresponding values for 2 were 3.5 eV (from absorption spectrum), 1.8 eV (from fluorescence spectrum), 0.69 eV, 2.8 ns, and +0.41 V

Synergistic enhancement in the microelectronic properties of poly-(dioctylfluorene) based Schottky devices by CdSe quantum dots

This paper reports the potential application of cadmium selenide (CdSe) quantum dots (QDs) in improving the microelectronic characteristics of Schottky barrier diode (SBD) prepared from a semiconducting material poly-(9,9-dioctylfluorene) (F8). Two SBDs, Ag/F8/P3HT/ITO and Ag/F8-CdSe QDs/P3HT/ITO, are fabricated by spin coating a 10 wt% solution of F8 in chloroform and 10:1 wt% solution of F8:CdSe QDs, respectively, on a pre-deposited poly(3-hexylthiophene) (P3HT) on indium tin oxide (ITO) substrate. To study the electronic properties of the fabricated devices, current-voltage (I-V) measurements are carried out at 25 °C in dark conditions. The I-V curves of Ag/F8/P3HT/ITO and Ag/F8-CdSe QDs/P3HT/ITO SBDs demonstrate asymmetrical behavior with forward bias current rectification ratio (RR) of 7.42 ± 0.02 and 142 ± 0.02, respectively, at ± 3.5 V which confirm the formation of depletion region. Other key parameters which govern microelectronic properties of the fabricated devices such as charge carrier mobility (µ), barrier height (ϕ ), series resistance (R ) and quality factor (n) are extracted from their corresponding I-V characteristics. Norde's and Cheung functions are also applied to characterize the devices to study consistency in various parameters. Significant improvement is found in the values of R , n, and RR by 3, 1.7, and 19 times, respectively, for Ag/F8-CdSe QDs/P3HT/ITO SBD as compared to Ag/F8/P3HT/ITO. This enhancement is due to the incorporation of CdSe QDs having 3-dimensional quantum confinement and large surface-to-volume area. Poole-Frenkle and Richardson-Schottky conduction mechanisms are also discussed for both of the devices. Morphology, optical bandgap (1.88 ± 0.5 eV) and photoluminescence (PL) spectrum of CdSe QDs with a peak intensity at 556 nm are also reported and discussed

Modeling of photodegradation process to remove the higher concentration of environmental pollution

Environmental organic pollutants are mineralized to harmless final-products such H2O and CO2 by photocatalytic advanced oxidation processes (AOPs). In photocatalytic-AOPs, an appropriate concentration of p-Cresol was mixed with certain amount of ZnO in 500 mL deionized water according to an experimental-design. Then the mixture was irradiated by UV-A lamp at different pH for 6 h. At specific time intervals, the sampling was carried out to calculate the efficiency of the photodegradation. Therefore, the photodegradation as a system consists of four input variables such irradiation time, pH, amount of ZnO and p-Cresol’s concentration while the only output was the efficiency. In this work, the system was modeled and optimized by semi-empirical response surface methodology. To obtain the empirical responses, the design was performed in laboratory. Then observed responses were fitted with several well-known models by regression process to suggest a provisional model. The suggested model which was validated by several statistical evidence, predicted the desirable condition with higher efficiency. The predicted condition consisted of irradiation time (280 min), pH (7.9), photocatalyst (1.5 g L−1), p-Cresol (95 mg L−1) and efficiency (95%) which confirmed by further experiments. The closed confirmation results has presented the removal (efficiency = 94.7%) of higher p-Cresol concentration (95 mg L−1) at shorter irradiation time in comparison with the normal photodegradation efficiency (97%) which included irradiation time (300 min), pH (7.5), photocatalyst amount (1.5 g L−1) and p-Cresol (75 mg L−1). As a conclusion, the modeling which is able to industrial scale up succeeded to remove higher concentration of environmental organic pollutants with ignorable reduction of efficiency

Experimental investigation of energy storage properties and thermal conductivity of a novel organic phase change material/MXene as A new class of nanocomposites

Energy storage is a global critical issue and important area of research as most of the renewable sources of energy are intermittent. In this research work, recently emerged inorganic nanomaterial (MXene) is used for the first time with paraffin wax as a phase change material (PCM) to improve its thermo-physical properties. This paper focuses on preparation, characterization, thermal properties and thermal stability of new class of nanocomposites induced with MXene nanoparticles in three different concentrations. Acquired absorbance (UV-Vis) for nanocomposite with loading concentration of 0.3 wt.% of MXene achieved ~39% enhancement in comparison with the pure paraffin wax. Thermal conductivity measurement for nanocomposites in a solid state is performed using a KD2 PRO decagon. The specific heat capacity (cp) of PCM based MXene is improved by introducing MXene. The improvement of cp is found to be 43% with 0.3 wt.% of MXene loaded in PCM. The highest thermal conductivity increment is found to be 16% at 0.3 wt.% concentration of MXene in PCM. Decomposition temperature of this new class of nanocomposite with 0.3 wt.% mass fraction is increased by ~6%. This improvement is beneficial in thermal energy storage and heat transfer applications

Switching and optics of ferroelectric liquid crystal devices

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Techno economic analysis of using solar water heaters with evacuated tubes in Khartoum, Sudan

This paper presents the techno-economic study of using solar water heaters employing evacuated tubes in Khartoum, Sudan. Sudan experiences high solar irradiation and is thus a good candidate for harnessing solar energy. One direct application of solar energy is for domestic water heating applications, which has the potential of significant savings on the national energy consumption if used extensively. This study will first introduce the technological and economic benefits of using solar water heated containing evacuated tubes, which have shown better efficiency compared to flat plate solar water heaters. The operational requirements and efficiency of this system will then be compared against the output and efficiency of an electric water heater. The relative costs of each system will also be analyzed and discussed. Also it found that the heat gained from the solar collector was enough for producing hot water and the amount of mass flow rate that was suitable for natural circulation, thus eliminating the need for a driving pump, and reducing the overall cost for the solar water heater system. The techno-economic analysis is then carried out in order to analyze the payback period for a range of number of households required to employ this system. This analysis indicates that a saving was 415.2 USD per year for 8 households and the payback period ranged between 0.98 and 1.43 year, thus rendering this technology as an attractive option for energy and cost savings for domestic applications. © Sila Science