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•Rod, flower and particle-like ZnO nanostructer were grown via PLAL-H technique.•ZnO morphology, crystallinity and optical properties were discussed.•Highly pure ZNSs were achieved ...from Zn metal and deionized water only.•Growth mechanism of ZnO nanostructure was established.•ZNSs morphology dependent photocatalytic activity was determined.
Using a simple combination of pulse laser ablation in liquid and hydrothermal (PLAL-H) approaches, we control the morphology of ZnO nanostructures (ZNSs) to determine the feasibility of their photocatalytic efficacy. These ZNSs are deposited on Si (100) substrates and two different morphologies are achieved. In this synergistic approach, PLAL synthesized NSs are used as a nutrient solution with different pH for further hydrothermal treatment at 110°C under varying growth time (5, 30 and 60min). Surface morphology, structure, composition, and optical characteristics of the prepared ZNSs are determined using FESEM, XRD, FTIR and Photoluminescence (PL) and UV–vis absorption measurements. The morphology revealed remarkable transformation from nanorods (NRs)/nanoflowers (NFs) (at pH 7.6) to nanoparticles (NPs)-like (at pH 10.5) structure. XRD patterns showed better polycrystallinity for NPs with enlarged band gap than NR/NF-like structures. Both PL and UV–vis spectral analysis of ZNPs exhibited higher surface area and deep level defects density dependent morphology, where the nutrient pH and growth time variation are found to play a significant role towards structural evolution. Furthermore, the photocatalytic activities of, such ZNSs are evaluated via sunlight driven photo-degradation of methylene blue (MB) dye. The photocatalytic efficiency of ZNPs is demonstrated to be much superior (97.4%) than ZNRs/ZNFs-like morphology (86%). Such enhanced photocatalytic activities of as-synthesized ZNPs is attributed to the synergism of the improved surface area and defects density, which is useful for promoting the adsorption of the MB dye and suppressed surface recombination of photo-generated charge carriers.
Trace chemical detection is important for a wide range of practical applications. Recently emerged two-dimensional (2D) crystals offer unique advantages as potential sensing materials with high ...sensitivity, owing to their very high surface-to-bulk atom ratios and semiconducting properties. Here, we report the first use of Schottky-contacted chemical vapor deposition grown monolayer MoS2 as high-performance room temperature chemical sensors. The Schottky-contacted MoS2 transistors show current changes by 2–3 orders of magnitude upon exposure to very low concentrations of NO2 and NH3. Specifically, the MoS2 sensors show clear detection of NO2 and NH3 down to 20 ppb and 1 ppm, respectively. We attribute the observed high sensitivity to both well-known charger transfer mechanism and, more importantly, the Schottky barrier modulation upon analyte molecule adsorption, the latter of which is made possible by the Schottky contacts in the transistors and is not reported previously for MoS2 sensors. This study shows the potential of 2D semiconductors as high-performance sensors and also benefits the fundamental studies of interfacial phenomena and interactions between chemical species and monolayer 2D semiconductors.
The preparation of activated carbon from coconut husk with H2SO4 activation (CSAC) and its ability to remove textile dyes (maxilon blue GRL, and direct yellow DY 12), from aqueous solutions were ...reported in this study. The adsorbent was characterized with Fourier transform infrared spectrophotometer (FT-IR), and scanning electron microscope (SEM). Various physiochemical parameters such as, contact time, initial dye concentration, adsorbent dosage, particle size, pH of dye solution and temperature were investigated in a batch-adsorption technique. Result showed that the adsorption of both GRL and DY 12 dyes was favorable at acidic pH. The adsorption uptake was found to increase with increase in initial dye concentration, and contact time but decreases with the amount of adsorbent, particle size, and temperature of the system. The chemisorption, intra-particle diffuse, pseudo-first-order and pseudo-second-order kinetic models were applied to test the experimental data. The pseudo-second order exhibited the best fit for the kinetic studies, which indicates that adsorption of (GRL, and DY 12) is limited by chemisorption process. The equilibrium data were evaluated using Langmuir, Freundlich, Temkin and Fritz–Schlunder isotherms. The Fritz–Schlunder model best describes the uptake of (GRL and DY 12) dye, which implies that the adsorption of textiles dyes in this study onto coconut husk activated carbon is heterogeneous with multi-layers. Thermodynamic parameters such as Gibbs free energy, enthalpy and entropy were determined. It was found that (GRL and DY 12) dye adsorption was spontaneous and endothermic.
Two-dimensional (2D) materials beyond graphene have drawn a lot of attention recently. Among the large family of 2D materials, transitional metal dichalcogenides (TMDCs), for example, molybdenum ...disulfides (MoS2) and tungsten diselenides (WSe2), have been demonstrated to be good candidates for advanced electronics, optoelectronics, and other applications. Growth of large single-crystalline domains and continuous films of monolayer TMDCs has been achieved recently. Usually, these TMDC flakes nucleate randomly on substrates, and their orientation cannot be controlled. Nucleation control and orientation control are important steps in 2D material growth, because randomly nucleated and orientated flakes will form grain boundaries when adjacent flakes merge together, and the formation of grain boundaries may degrade mechanical and electrical properties of as-grown materials. The use of single crystalline substrates enables the alignment of as-grown TMDC flakes via a substrate–flake epitaxial interaction, as demonstrated recently. Here we report a step-edge-guided nucleation and growth approach for the aligned growth of 2D WSe2 by a chemical vapor deposition method using C-plane sapphire as substrates. We found that at temperatures above 950 °C the growth is strongly guided by the atomic steps on the sapphire surface, which leads to the aligned growth of WSe2 along the step edges on the sapphire substrate. In addition, such atomic steps facilitate a layer-over-layer overlapping process to form few-layer WSe2 structures, which is different from the classical layer-by-layer mode for thin-film growth. This work introduces an efficient way to achieve oriented growth of 2D WSe2 and adds fresh knowledge on the growth mechanism of WSe2 and potentially other 2D materials.
Bandgap engineering of graphene is an essential step toward employing graphene in electronic and sensing applications. Recently, graphene nanoribbons (GNRs) were used to create a bandgap in graphene ...and function as a semiconducting switch. Although GNRs with widths of <10 nm have been achieved, problems like GNR alignment, width control, uniformity, high aspect ratios, and edge roughness must be resolved in order to introduce GNRs as a robust alternative technology. Here we report patterning, characterization, and superior chemical sensing of ultranarrow aligned GNR arrays down to 5 nm width using helium ion beam lithography (HIBL) for the first time. The patterned GNR arrays possess narrow and adjustable widths, high aspect ratios, and relatively high quality. Field-effect transistors were fabricated on such GNR arrays and temperature-dependent transport measurements show the thermally activated carrier transport in the GNR array structure. Furthermore, we have demonstrated exceptional NO2 gas sensitivity of the 5 nm GNR array devices down to parts per billion (ppb) levels. The results show the potential of HIBL fabricated GNRs for the electronic and sensing applications.
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Perturbative cross-sections in QCD are beset by logarithms of kinematic invariants, whose arguments vanish when heavy particles are produced near threshold. Contributions of this type often ...need to be summed to all orders in the coupling, in order to improve the behaviour of the perturbative expansion, and it has long been known how to do this at leading power in the threshold variable, using a variety of approaches. Recently, the problem of extending this resummation to logarithms suppressed by a single power of the threshold variable has received considerable attention. In this paper, we show that such next-to-leading power (NLP) contributions can indeed be resummed, to leading logarithmic (LL) accuracy, for any QCD process with a colour-singlet final state, using a direct generalisation of the diagrammatic methods available at leading power. We compare our results with other approaches, and comment on the implications for further generalisations beyond leading-logarithmic accuracy.
This study aims to explore the role of customer knowledge management (CKM) and satisfaction as antecedents of customer trust, and the mediating function of customer trust in the knowledge-loyalty and ...satisfaction-loyalty in the Saudi banking sector. This study intends to provide light on the significance of CKM and the ways in which it can support consumer trust, loyalty, and satisfaction. Data came from 600 consumers who responded to an online survey. By using regression analysis and descriptive statistics, seven hypotheses were created and tested. The findings exhibited that customer trust has a major impact on loyalty and that customer trust is positively impacted by CKM and satisfaction. Additionally, trust partially mediates the relationship between knowledge, loyalty, and satisfaction. The study contributes to the literature by examining the factors that influence customer loyalty, CKM engagement, satisfaction, and trust in the context of the Saudi banking industry. These research findings are helpful for managers and strategists in figuring out how to create customer loyalty programs that are a fit for their target market. The study is limited to the Saudi banking sector and may not be generalizable to other industries. Additionally, the study is based on self-reported data from customers, which may not accurately reflect their true opinions and behaviors.
The effect of Web atmospheric clues on the purchase intention of Jordanian shoppers has been evaluated in this study, along with the interventions of Website gratification. The primary data ...collection for testing the research model via a survey method has been performed from Jordan's capital city, namely Amman. The tenure of data collection from Amman is from July to January 2020. The Structural Equation Modeling method was used to analyze the data with AMOS 22.0 software. Convergent and discriminatory legitimacy of the measurement model has been estimated with the use of confirmatory factor analysis. The satisfaction component effectively negotiates the impact of Website clues on the intent of purchase. Moreover, the purchase intention is a consequent effect of the satisfaction caused by these preliminary factors. The e-retailers and marketers of Jordan are able to interpret the influence of multiple stimulating factors on the satisfaction gained from Web-related services with the help of the outcomes of this study. It is the prerogative of online retailers to ensure the delivery of the strongest atmospheric clues impacting the Website satisfaction to the shoppers. In the context of Jordanians, this study establishes that Web managers should designate a higher number of resources to the clues that enhance the excitement value of the atmospherics of Web portals. This study boosts the knowledge of the researchers having academic interest and practical inclination toward the aspects of developing economies and adds to their current level of knowledge regarding e-retailing and online buying behavior.
Two-dimensional (2D) layered tungsten diselenides (WSe2) material has recently drawn a lot of attention due to its unique optoelectronic properties and ambipolar transport behavior. However, direct ...chemical vapor deposition (CVD) synthesis of 2D WSe2 is not as straightforward as other 2D materials due to the low reactivity between reactants in WSe2 synthesis. In addition, the growth mechanism of WSe2 in such CVD process remains unclear. Here we report the observation of a screw-dislocation-driven (SDD) spiral growth of 2D WSe2 flakes and pyramid-like structures using a sulfur-assisted CVD method. Few-layer and pyramid-like WSe2 flakes instead of monolayer were synthesized by introducing a small amount of sulfur as a reducer to help the selenization of WO3, which is the precursor of tungsten. Clear observations of steps, helical fringes, and herringbone contours under atomic force microscope characterization reveal the existence of screw dislocations in the as-grown WSe2. The generation and propagation mechanisms of screw dislocations during the growth of WSe2 were discussed. Back-gated field-effect transistors were made on these 2D WSe2 materials, which show on/off current ratios of 106 and mobility up to 44 cm2/(V·s).
Non-enzymatic sensing of chlorpyrifos (CPF) has been demonstrated over structurally functionalized the ternary bio nanocomposite comprised of cupric oxide, sodium alginate, and polyaniline-based ...hybrid (CuO/SA-g-PANI) based electrode using a laboratory designed portable potentiometric set up. The prepared composite and constituents were characterized for structure, morphology, and physical properties with the help of fourier transform infrared, X-ray diffraction, Scanning electron microscope, and other relevant standard methods. The obtained results revealed the formation of porous, electrical conductivity, structurally functionalized, responsiveness composite due to molecular engineering, and structural synergism for sensing applications. Further, the film of the prepared composite was explored as the electrode for nonenzymatic potentiometric sensing of residual chlorpyrifos in synthetic and natural sample i.e., tap water, soil, mango, and cabbage. The sensor exhibits a wider sensing range 1.0–120.0 μM, improved sensitivity 1.8790 mV·μM−1·cm−2, detection limit 0.375 μM, response time 120 s, recovery time 16 s with 99.80 % accuracy, and stability of 72 days at neutral 7.0 pH and ambient temperature i.e. 25 °C. Further, the sensing mechanism has been also explained on the basis of structural change in CPF and electrode materials due to their surface interaction along with formation induced electrode potential.
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•Synergistic responsiveness and functionality in CuO and Sodium alginate grafted polyaniline.•Non enzymatic chlorpyrifos sensing over CuO and Sodium alginate grafted polyaniline.•Sensor exhibits good sensing parameter and long term stability for 72 days.
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