Nanosheet-Assembled MnO2-Integrated Electrode Based on the Low-Temperature and Green Chemical Route

The development of superior electrochemical energy-storage devices designed through a facile, cost-efficient, and green synthesis technique is the key to addressing the intermittent nature of renewable energy sources such as solar and wind energy. In our present work, we design a simple, surfactant-free, and low-temperature chemical strategy to prepare novel integrated, MnO2 composite electrodes with two-dimensional (2D) nanosheet film directly supported on three-dimensional (3D) conductive nickel foam. Benefiting from the specific 2D nanosheet architecture to provide a large interfacial contact area and highly conductive metal scaffolds to facilitate fast electron transfer, the novel nanosheet-assembled MnO2-integrated electrodes exhibit higher specific capacitance of 446 F g−1 at the current density of 1 A g−1 compared with nanostructured MnO2 and commercial MnO2 powder electrodes. More importantly, the as-synthesized devices are able to achieve an outstanding cycling performance of 95% retention after 3000 cycles. The present work, which is based on the low-temperature chemical route to deposit active materials on the conductive substrate, provides new insights into designing a binder-free supercapacitor system to improve the specific capacitance, cycling, and rate performance as next-generation, energy-storage devices.

Biomimetic non-classical crystallization induced hierarchically structured efficient circularly polarized phosphors

Hierarchically structured chiral luminescent materials hold promise for achieving efficient circularly polarized luminescence. However, a feasible chemical route to fabricate hierarchically structured chiral luminescent polycrystals is still elusive because of their complex structures and complicated formation process. We here report a biomimetic non-classical crystallization (BNCC) strategy for preparing efficient hierarchically structured chiral luminescent polycrystals using well-designed highly luminescent homochiral copper(I)-iodide hybrid clusters as basic units for biomimetic crystallization. By monitoring the crystallization process, we unravel the BNCC mechanism, which involves crystal nucleation, nanoparticles aggregation, oriented attachment, and mesoscopic transformation processes. We finally obtain the circularly polarized phosphors with both high luminescent efficiency (32%) and high luminescent dissymmetry factor (1.5 × 10-2), achieving the first demonstration of a circularly polarized phosphor converted light emitting diode with a polarization degree of 1.84% at room temperature. Our designed BNCC strategy provides a simple, reliable and large-scale synthetic route for preparing bright circularly polarized phosphors.

Development of bio-chemical route to C5 plasticizer synthesis using glutaric acid produced by metabolically engineered Corynebacterium glutamicum

Corynebacterium glutamicum was engineered to produce glutaric acid by metabolic engineering approaches starting from the heterologous introduction of glutaric acid biosynthesis pathway by the expression of Pseudomonas putida davT, davD,...

A Sensitive Electrochemical Sensor Based on Sonogel-Carbon Material Enriched with Gold Nanoparticles for Melatonin Determination

In this work, the development of an electrochemical sensor for melatonin determination is presented. The sensor was based on Sonogel-Carbon electrode material (SNGCE) and Au nanoparticles (AuNPs). The low-cost and environmentally friendly SNGCE material was prepared by the ultrasound-assisted sonogel method. AuNPs were prepared by a chemical route and narrow size distribution was obtained. The electrochemical characterization of the SNGCE/AuNP sensor was carried out by cyclic voltammetry in the presence of a redox probe. The analytical performance of the SNGCE/AuNP sensor in terms of linear response range, repeatability, selectivity, and limit of detection was investigated. The optimized SNGCE/AuNP sensor displayed a low detection limit of 8.4 nM melatonin in synthetic samples assessed by means of the amperometry technique. The potential use of the proposed sensor in real sample analysis and the anti-matrix capability were assessed by a recovery study of melatonin detection in human peripheral blood serum with good accuracy.

Chemical Route Manufactured ZnO Nanoparticles And Their Biological Accumulation

ZnO nanocrystalline powder was successfully synthesized via co-precipitation method coupled with high annealing treatment. X-ray diffraction analysis revealed that the NPs have a pure hexagonal wurtzite structure with a mean crystallite size of approximately 59 nm. FESEM observations along with EDS analysis indicated the formation of fine particles in the nanoscale regime, with hexagonal shape and high purity. Both Raman and photoluminescence characterizations confirmed the high crystalline and the optical quality of the synthesized ZnO NPs. The assessment of the impact of ZnO-based nanoparticles and their effects on body and bioaccumulative bioindicators of pollution, Helix aspersa snails was performed in order to preserve the safe development of nanotechnology.

Fabrication of Cobalt-Based Nano-Composite Film for Corrosion Mitigation of Copper in Flow Chloride Medium

Corrosion of metals leads to high maintenance costs, as well as potential threats to structural health and safety. Here, we demonstrate the coating of cobalt tungstate (CoWO4) nanoparticles (NPS)/5-mercapto-1-phenyl-1 H-tetrazole derivative (MPT) used as a nano-composite film on Cu surface for the blocking of micropores to hinder the propagation of metastable pits in an aggressive NaCl medium. The mechanism of interaction between the nanoparticles and tetrazole derivative, in addition to the mode of anchoring to the metal surface and blocking the penetration of chloride ions (Cl−), are all investigated. In this investigation, CoWO4 is synthesized via a wet chemical route and thereafter, is combined with MPT at an optimized ratio thus formulating a nano-composite corrosion inhibitor which in solution gets coated on Cu surface. Atomic force and scanning electron microscopic images of the bare Cu reveal dip pits, which by the coating of the nano-composite are suppressed at the nucleation stage during exposure to the aggressive 3.5% NaCl electrolyte under flow conditions. Electrochemical analysis shows high protection of Cu up to 97% efficiency in the presence of the newly formulated nano-composite inhibitor film.

Structural Optical Magnetic And Photocatalytic Properties of Ferromagnetic P-Type NiO: N-Type ZnO Nanocomposites

The semiconductor-transition conducting metal oxides (p-type NiO: n-type ZnO) nanocomposites (NCs) called (NZO) are successfully prepared by a simple wet-chemical route followed by the systematic sintering at different temperatures such as 400°C, 500°C, 600°C, and 700 °C. The structure and morphology of the samples were characterized by X-ray diffraction (XRD), high-resolution scanning/transmission electron microscopy (HR-SEM/TEM), and energy-dispersive X-ray spectrometry (EDX) techniques. XRD analysis reveals that the average crystallite size of the NZO NCs was found to be in the range 16-18 nm. The synthesized sample discloses a ferromagnetic behavior. The photocatalytic degradation of rhodamine B in an aqueous solution was superior at the NZO NC at 600 °C in comparison with other samples. Here, the NZO NCs display to be good candidates for magnetic and photocatalytic application.

Synthesis and applications of zinc oxide for removal of various pollutants: A review

The versatility of zinc oxide applications in the removal of various pollutants has attracted a wide interest of researchers in the past decade. Numerous studies reported on zinc oxide synthesis pathways and resulting nanoparticle morphologies, applications, formation mechanisms and synthesis parameters. In this review the reported zinc oxide synthesis methods are classified into chemical, physical and biological routes; they are evaluated in terms of the required chemicals, synthesis conditions and the resulting morphologies and properties of zinc oxide. The chemical route of zinc oxide synthesis covers precipitation, micro-emulsion, solgel, solvothermal and hydrothermal paths. The physical route includes laser ablation and high energy ball milling, while the biological route covers plant extracts and microbe mediated synthesis. The mechanisms of zinc oxide formation of the mentioned routes are based on one or more of the following processes: particle nucleation, diffusional growth, Ostwald ripening, particle aggregation and sintering. The most influencing synthesis parameters overall are temperature, drying duration and additives’ effect. Higher temperatures (>200°C) commonly produce larger particles of zinc oxide (> 80 nm); the prolong duration (> 60 min) often results in the agglomeration and sintering of zinc oxide particles. However, additives may mitigate agglomeration extent. Overall, the chemical route is more preferable due to its flexibility that is also linked to the greater variability of zinc oxide particles. The physical method produces more consistent zinc oxide particles but requires higher energy inputs. The biological method is very promising and associated with low chemicals consumptions and good quality of zinc oxide.