Synthesis and Characterization of Soluble Thiophene-Selenophene- and Tellurophene-Vinylene Copolymers

Organic electronic devices based on polymers received significant attention in the last decade, especially for organic photovoltaics (OPVs) and field-effect transistors (OFETs) despite their performances and stability clearly falling short of today's state-of-the-art crystalline silicon or copper indium germanium selenide (CIGS)-based devices. Flexibility in the manufacturing, light weight, lower fabrication cost, ease of integration into various devices, and large area coating are some of the major potential advantages of polymers over inorganic devices. 1 Among organic polymers, conjugated polymers attracted widespread attention for a wide range of applications. Thiophene-containing conjugated polymers, especially, poly(3-alkylthiophne) (P3AT) has been subjected to intensive research over last decade due to their excellent optical and electronic properties. 2 Moreover, poly(thienylenevinylene) (PTV) class of polymers displays high charge carrier mobilities in OFETs and promising performances in OPVs. 3 When a single solubilizing alkyl chain is included onto the PTV backbone, the resulting copolymer can be solution processed for optical devices. One simple strategy to manipulate the copolymer property is by changing the heteroatom of the thiophene from sulfur to other chalcogens, selenium or tellurium. 4 Theoretical calculations indicated that substitution with selenium or tellurium may reduce the optical band gap of the resulting polymer in comparison to their sulfur-containing analogues. Inclusion of larger and more polarizable selenium or tellurium also expected to have a strong influence on the charge transport properties. Notably, Heeney and co-workers showed that the band gap of P3AT can be reduced by as much as 0.3 eV by only substituting sulfur with selenium in the polymer backbone. 5 The reduction of band gap resulted from larger and more polarizable selenium facilitate better π orbital overlap with the polymer backbone and thus stabilize the polymer LUMO (lowest unoccupied molecular orbital). Low-lying LUMO levels are believe to facilitate both electron injection and transport. Recently, PBDTT-SeDPP polymer showed a high Jsc of 16.8 mA/cm2, a Voc of 0.69 V, and a FF of 62%, enabling the best PCE of 7.2%. 6 However, despite fascinating properties of selenium substituted polymers, tellurium containing polymers are less explored, may be due to challenging tellurium chemistry. Jahnke and co-workers recently reported first soluble tellurophene polymer, poly(3-alkyltellurophene) (P3ATe), prepared by both electrochemical and Kumuda coupling polymerization method. 7 Even though, preliminary PCE (1.1%) was modest, tellurium substitution resulted in red-shifted film absorption. In this contribution, we report the synthesis and characterization of vinylene copolymers containing 3-alkylthiophene, selenophene or tellurophene. This allows us systematically investigate the role of selenium or tellurium on the polymer properties. Here, we report the first synthesis of novel 2,5-dibrominated 3-alkyltellurophene monomer and its Pd[0]-catalyzed copolymerization with (E)1,2-bis(tributylstannyl)ethylene to afford poly(3-alkyltellurophenylenevinylene) (P3ATeV). 8 We compare the optoelectronic properties of P3ATeV with analogous sulfur (P3ATV) and selenium (P3ASV) containing polymers. Preliminary OFET data will also be incorporated. Scheme 1. Structures of P3AX, P3AXV copolymers.Qscienc

Microwave-Assisted Solvothermal Synthesis of Mo-Doped TiO2 with Exceptional Textural Properties and Superior Adsorption Kinetics

Assigned to their outstanding physicochemical properties, TiO2-based materials have been studied in various applications. Herein, TiO2 doped with different Mo contents (Mo-TiO2) was synthesized via a microwave-assisted solvothermal approach. This was achieved using titanium (IV) butoxide and molybdenum (III) chloride as a precursor and dodecylamine as a surface directing agent. The uniform effective heating delivered by microwave heating reduced the reaction time to less than 30 min, representing several orders of magnitude lower than conventional heating methods. The average particle size ranged between 9.7 and 27.5 nm and it decreased with increasing the Mo content. Furthermore, Mo-TiO2 revealed mesoporous architectures with a high surface area ranging between 170 and 260 m2 g−1, which is superior compared to previously reported Mo-doped TiO2. The performance of Mo-TiO2 was evaluated towards the adsorption of Rhodamine B (RhB). In contrast to TiO2, which revealed negligible adsorption for RhB, Mo-doped samples depicted rapid adsorption for RhB, with a rate that increased with the increase in Mo content. Additionally, Mo-TiO2 expressed enhanced adsorption kinetics for RhB compared to state-of-the-art adsorbents. The introduced synthesis procedure holds a grand promise for the versatile synthesis of metal-doped TiO2 nanostructures with outstanding physicochemical properties.NPRP Grant no. NPRP 12S-0304-190218 from the Qatar National Research Fund (a member of the Qatar Foundation). The statements made herein are solely the responsibility of the authors

Improved electrochemical performance of SiO2-coated Li-rich layered oxides-Li1.2Ni0.13Mn0.54Co0.13O2

Lithium-rich layered oxides (LLOs) such as Li1.2Ni0.13Mn0.54Co0.13O2 are suitable cathode materials for future lithium-ion batteries (LIBs). Despite some salient advantages, like low cost, ease of fabrication, high capacity, and higher operating voltage, these materials suffer from low cyclic stability and poor capacity retention. Several different techniques have been proposed to address the limitations associated with LLOs. Herein, we report the surface modification of Li1.2Ni0.13Mn0.54Co0.13O2 by utilizing cheap and readily available silica (SiO2) to improve its electrochemical performance. Towards this direction, Li1.2Ni0.13Mn0.54Co0.13O2 was synthesized utilizing a sol-gel process and coated with SiO2 (SiO2 = 1.0 wt%, 1.5 wt%, and 2.0 wt%) employing dry ball milling technique. XRD, SEM, TEM, elemental mapping and XPS characterization techniques confirm the formation of phase pure materials and presence of SiO2 coating layer on the surface of Li1.2Ni0.13Mn0.54Co0.13O2 particles. The electrochemical measurements indicate that the SiO2-coated Li1.2Ni0.13Mn0.54Co0.13O2 materials show improved electrochemical performance in terms of capacity retention and cyclability when compared to the uncoated material. This improvement in electrochemical performance can be related to the prevention of electrolyte decomposition when in direct contact with the surface of charged Li1.2Ni0.13Mn0.54Co0.13O2 cathode material. The SiO2 coating thus prevents the unwanted side reactions between cathode material and the electrolyte. 1.0 wt% SiO2-coated Li1.2Ni0.13Mn0.54Co0.13O2shows the best electrochemical performance in terms of rate capability and capacity retention.This publication was made possible by NPRP Grant # NPRP11S-1225-170128 from Qatar National Research Fund (a member of the Qatar Foundation). Statements made herein are solely the responsibility of the authors. FE-SEM analysis was accomplished at the Central Laboratory Unit (CLU), Qatar University, Doha, Qatar, TEM analysis was conducted at the Core Labs., QEERI, HBKU, Qatar and XPS analysis was accomplished at the Gas Processing Center (GPC), Qatar University, Doha, Qatar.Scopu

Qur’anic Ethics for Environmental Responsibility: Implications for Business Practice

Despite the growing interest in examining the role of religious beliefs as a guide towards environmental conscious actions, there is still a lack of research informed by an analysis of divine messages. This deficiency includes the extent to which ethics for environmental responsibility are promoted within textual divine messages; types of environmental themes promoted within the text of divine messages; and implications of such religious environmental ethics for business practice. The present study attempts to fill this gap by conducting a thorough content analysis of environmental themes within the divine message of Muslims (the Qur’an) focusing on their related ethical aspects and business implications. The analysis has revealed 675 verses in 84 chapters throughout all 30 parts of the Qur’an, with environmental content relating to the core components of the natural world, i.e. human beings, water, air, land, plants, animals, and other natural resources. This environmental content and its related ethics are grounded on the belief that humans are vicegerents of God on the earth and their behaviours and actions are motivated by earthly and heavenly rewards. Implications of these findings for different sectors/businesses are also highlighted

Identifying crack parameters in slow rotating machinery using vibration measurements and hybrid neuro-particle swarm technique

Low-cycle fatigue-initiated cracks may result in failure in slow-rotating equipments. Online monitoring to identify such fault/crack parameters, namely crack size and crack location, would be critical in providing an early warning signal to the operator and would be used in calculating estimate about the remaining safe life of the equipment in operation. In an earlier study, a scaled-down slow-rotating washer drum was constructed to experimentally investigate the vibrations of a cracked rotor and/or drums. Cracks were simulated using the bolt removal method (BRM), and the vibration signals identifying signatures of certain cracks were measured. Thereafter, a 3D finite element model was used to solve the forward analysis of the inverse problem of crack identification. In this paper, the scaled-down experimental setup is introduced to cracks at different locations of the drum/rotor. Vibration signals identifying signatures of such cracks are measured. Since noisy signals, similar patterns of faults, and similar vibration fault signals create particular challenges for feature extraction systems, two techniques for feature extraction are considered and compared in this work. The fast Fourier transform (FFT) of the vibration signals showing variation in amplitude of the harmonics as time progresses are presented for comparison with the full time signal feature extraction. A hybrid particle-swarm artificial Neural Networks (neuroparticle swarm) is used to identify both the crack size andcrack location. The hybrid neuro-particle swarm technique is compared with the previously investigated fuzzy genetic algorithms. 2010 by ASME.Scopus2-s2.0-8488145829

Low-Temperature CO Oxidation Over CuO-TiO2 Nanocatalysts

Among the diverse catalytic processes, the heterogeneous catalytic CO oxidation is an important reaction for removal of small amounts of poisoning CO in fuel cell applications and environmental remediation. Therefore, there is a great need to develop highly active and stable nanocatalysts for catalytic CO oxidation at low temperature. Plasmonic nanocatalysts supported on reducible metal oxide such as CeO2 and TiO2 have been known for their superior catalytic activity at very low temperature but they are expensive and could suffer from particle agglomeration and sintering at high operating temperature (Veith, Lupini et al. 2009). Transition metals supported on reducible metal oxides are good substituents catalysts because of their low cost and wide-use along with activities per unit surface area similar to those of noble metal catalysts. They been shown to possess high oxygen release capacity at high range of temperature and have been shown as good candidate materials for oxygen storage and to provide oxygen for combustion and oxidation reaction at high temperature. (Royer and Duprez 2011; Hedayati, Azad et al. 2012; Song, Liu et al. 2013). In particular, supported CuO nanostructures have received a great deal of attention as non-expensive and non-plasmonic catalysts for oxidation reaction. (Caputo, Lisi et al. 2007; Hornes, Hungria et al. 2009; Royer and Duprez 2011; In, Vaughn et al. 2012; Komarneni, Shan et al. 2012; Chen, Xu et al. 2015; Fang, Xing et al. 2015; Kim and Liu 2015) In this study, we have developed a highly stable and active CuO-TiO2 nanocatalyst that can catalyze the CO oxidation at low temperature window between 80–200°C. The CuO-TiO2 nanocatalysts were prepared by the hydrothermal synthesis of TiO2 nanotubes followed by the deposition precipitation of CuO nanoparticles in alkaline conditions. We first prepared the TiO2 nanotube support by the hydrothermal treatment of TiO2 spherical particles in strong alkaline solution at 140°C. We then synthesized a series of CuO-TiO2 catalysts by deposition precipitation at constant pH, with sodium carbonate as the alkali precipitating agent and different loading ratios of Cu to TiO2 between 2% and 30 wt.%. We studied the morphological and structural properties of prepared nanocatalysts using standard physical techniques including SEM, EDX, TEM, TGA, XRD and XPS in order to understand the structure-property relationship and to optimize their catalytic activity. We carried out multiple catalytic CO oxidation cycles in a continuous flow fixed-bed reactor at low temperature range (25–300°C) and studied the catalytic activity of the different CuO-TiO2 nanocatalysts and their stability under stream. We also studied the effect of shape of the TiO2 support and the effect of the mole ratio of CuO loading on the CO conversion rates. The catalytic activity of the single counterparts of CuO and TiO2 were measured for comparison. The experimental results revealed that the CuO nanoparticles supported on TiO2 nanostructures exhibited higher activity and enhanced CO conversion rates at lower temperature, compared to un-supported CuO nanoparticles. The increased activity at lower activation temperature is probably due to the increased degree of dispersion of the active CuO phase on the TiO2 support as concluded from the EDX mapping study. Moreover, the results showed that the correlation between the catalytic activity of CuO-TiO2 nanocatalysts and both the shape and crystalline phase of the TiO2 support. The CuO supported on TiO2 nanotubes demonstarted enhanced CO conversion rates at lower temperature compared to that supported on TiO2 nanospheres. In all samples the CuO-TiO2 nanocatalysts calcined at 400°C exhibited the anatase phase of the TiO2 nanotubes support and demonstrated higher activity. The results also showed that increasing the Cu to Ti ratio could lower the activation temperature needed for CO to CO2 conversion probably due to the enhanced synergetic effect of the two mixed metal oxides. In addition, the XPS study of the CuO-TiO2 composite oxide structure indicated high degree of oxygen deficiency in CuO-TiO2 nanocatalysts with higher Cu to TiO2 loading and this could result in CO oxidation rates. The prepared CuO-TiO2 nanocatalyst demonstrated a high stability for CO oxidation for test periods of up to 5 h under stream at 200°C. The prepared CuO-TiO2 nanocatalysts could have potential applications in hydrogen purification in fuel cell systems and for CO removal in carbon dioxide lasers and in air quality industries.qscienc

Investigations into structure-property relationships of novel Ru(II) dyes with N,N?-Diethyl group in ancillary ligand for dye-sensitized solar cells

Structure-property relationships of four novel bipyridyl Ru(II) complexes, denoted as SD-22, SD-24, SD-26 and SD-28, are reported herein. The molecular structures of all four photosensitizers were confirmed using FT-IR, 1H NMR and mass spectrometry. Photovoltaic characteristics of the photosensitizers were evaluated under 1.5 a.m. standard illumination condition, in presence of deoxycholic acid as co-adsorbent, and subsequently compared to the performance of the benchmark, Z907. SD-22 showed an IPCE of 52% and 50% at 440 nm and 550 nm, respectively, a short-circuit photocurrent density (JSC) of 17.37 mA cm−2, open-circuit photovoltage (VOC) of 0.63 V and fill factor (FF) of 0.66, producing an overall conversion efficiency (η) of 7.31%, which outperformed Z907 (7.02%) under the same experimental device conditions. The η of the other photosensitizers is in the following order: SD-22 > SD-28 > SD-26 > SD-24. Photosensitizer SD-22 has N,N′-dialkyl group attached to a benzene ring while SD-24 has N,N′-dialkyl without a benzene ring. The extended conjugation in SD-22 translated into higher overall solar-to-electric conversion efficiency. Substitution of dialkylamino-based ancillary ligands of Ru(II) dyes SD-26 and SD-28 with –OCH3 and –OC6H13 also demonstrated that the photovoltaic performance of polypyridyl ruthenium photosensitizers is a function of the donating power of ancillary ligands as well as the steric effect of alkoxy auxochromes at –ortho position.The authors would like to thank the Higher Education Commission, Pakistan , Pakistan for financial assistance of this project. Facilities in CIRBS and CAEPE at International Islamic University, Islamabad, Pakistan, HEC 's support in the form of SRGR grant# 2505 (21-2505/SRGP/R&D/HEC/2019 ) and NRPU grant# 8227 are also acknowledged. Appendix AScopu