Preface

Click on the DOI link to access the article (may not be free).Energy and environmental issues are of great concerns for the public and will keep increasing in the next few decades. The demand for clean energy sources in our current society also increases with large-scale economic developments and population growth. It is crucial to build clean energy systems

Synthesis of hierarchical wo3 microspheres for photoelectrochemical water splitting application

In this work, hierarchical WO3 microspheres were synthesized using chemical bath deposition. The morphology of the synthesized sample was studied using scanning electron microscopy (SEM). The hierarchical WO3 microspheres formed from spontaneously self-assembled nanosheets have a high specific surface area. Structural characterizations of sample were performed using X-ray diffraction (XRD) and Raman spectroscopy. Analysis of XRD spectra showed that synthesized particles have a monoclinic modification. The optical properties of the sample were studied using UV-Vis diffuse reflectance absorption spectra. The value of the energy gap calculated from the absorption spectra is 2.2 eV, which indicates high light absorption ability. A photocurrent study was done to investigate the photocatalytic activity. The photoelectrode was prepared using hierarchical WO3 microspheres and polymer deposited on fluorine doped tin oxide (FTO) glass via spin coating technique. A remarkable photocurrent density of 18 A/cm2 at 0.5 V was achieved. The elongated structures improved light absorption ability and photocatalytic activity

Strategic synthesis of 2D and 3D conducting polymers and derived nanocomposites

In recent decades, there has been a great deal of interest in conducting polymers due to their broad applications. At the same time, various synthetic techniques have been developed to produce various nanostructures of the conducting polymers with their fascinating properties. However, the tech-niques for the manufacture of 2D nanosheets are either complex or expensive. No comprehensive approach for constructing 2D and 3D materials or their composites has been documented. Herein, a simple and scalable synthetic protocol is reported for the design of 2D, 3D, and related conducting polymer nanocomposites by interface manipulation in a bicontinuous microemulsion system. In this method, diverse bicontinuous thin layers of oil and water are employed to produce 2D nanosheets of conducting polymers. For the fabrica-tion of 3D polypyrrole (PPY) and their composites, specially designed linkers of the monomers are applied to lock the 3D networks of the conducting polymers and their composites. The technique can be extended to the fabrication of most conducting polymer composites, being cost-effective and easily scalable. The optimum electrical conductivity obtained for 2D PPY nanosheets is 219 S cm−1, the highest literature value reported to date to the best of knowledge

THREE-DIMENSIONAL FINGERPRINT SPECTROSCOPY STUDY ON THE BIOPOLYMER SYSTEM OF POLYPHENOL OXIDASE BINDING WITH CUMALIC ACID

The protection of Cumalic acid (CA), antioxidant, in the biochemical process in nature has aroused great interest. Polyphenol oxidase (PPO), an enzyme, plays a vital function in aging and browning of plants, such as vegetables, fruits, and mushrooms. The interaction of CA and PPO reveals the important information in metabolism and aging. Thus, the molecular mechanism of CA binding with polyphenol oxidase (PPO) was explored by combining spectroscopic methods with molecular modeling. A three-dimensional fingerprint of the CA-PPO complex was built for the first time to characterize the biopolymer interaction between CA and PPO. Application of the spectroscopic methods indicated that CA effectively quenched the intrinsic fluorescence of PPO. The enthalpy change (ΔH°) and entropy change (ΔS°) suggested that the CA-PPO complex was predominantly stabilized by hydrophobic interactions CA and PPO. Building the λ-UV-F fingerprint of CA-PPO made it possible to demonstrate the three-dimensional interactions between CA and PPO. Subsequently, molecular modeling demonstrated that CA was primarily bound to PPO by hydrophobic interactions and hydrogen bonds located at amino acid residues Ala202, His38, His54, and Ser206. The computational simulations were consistent with the spectral experiments demonstrating confidence in the three-dimensional model determined of the CA-PPO interaction

Simple top-down preparation of magnetic Bi0.9_{0.9}Gd0.1_{0.1}Fe1−x_{1-x}Tix_xO3_3 nanoparticles by ultrasonication of multiferroic bulk material

We present a simple technique to synthesize ultrafine nanoparticles directly from bulk multiferroic perovskite powder. The starting materials, which were ceramic pellets of the nominal compositions of Bi$_{0.9}$Gd$_{0.1}$Fe$_{1-x}$Ti$_x$O$_3$ (x = 0.00-0.20), were prepared initially by a solid state reaction technique, then ground into micrometer-sized powders and mixed with isopropanol or water in an ultrasonic bath. The particle size was studied as a function of sonication time with transmission electron microscopic imaging and electron diffraction that confirmed the formation of a large fraction of single-crystalline nanoparticles with a mean size of 11-13 nm. A significant improvement in the magnetic behavior of Bi$_{0.9}$Gd$_{0.1}$Fe$_{1-x}$Ti$_x$O$_3$ nanoparticles compared to their bulk counterparts was observed at room temperature. This sonication technique may be considered as a simple and promising route to prepare ultrafine nanoparticles for functional applications.Comment: 7 pages, 5 figure

Multiferroic Properties of Nanocrystalline BaTiO3

Some of the Multiferroics [1] form a rare class of materials that exhibit magnetoelectric coupling arising from the coexistence of ferromagnetism and ferroelectricity, with potential for many technological applications.[2,3] Over the last decade, an active research on multiferroics has resulted in the identification of a few routes that lead to multiferroicity in bulk materials.[4-6] While ferroelectricity in a classic ferroelectric such as BaTiO3 is expected to diminish with the reducing particle size,[7,8] ferromagnetism cannot occur in its bulk form.[9] Here, we use a combination of experiment and first-principles simulations to demonstrate that multiferroic nature emerges in intermediate size nanocrystalline BaTiO3, ferromagnetism arising from the oxygen vacancies at the surface and ferroelectricity from the core. A strong coupling between a surface polar phonon and spin is shown to result in a magnetocapacitance effect observed at room temperature, which can open up possibilities of new electro-magneto-mechanical devices at the nano-scale.Comment: 15 pages, 5 figure

Developing Biotemplated Data Storage: Room Temperature Biomineralization of L1<inf>0</inf> CoPt Magnetic Nanoparticles

L10 cobalt platinum can be used to record data at approximately sixfold higher densities than it is possible to on existing hard disks. Currently, fabricating L10 CoPt requires high temperatures (≈500 °C) and expensive equipment. One ecological alternative is to exploit biomolecules that template nanomaterials at ambient temperatures. Here, it is demonstrated that a dual affinity peptide (DAP) can be used to biotemplate L10 CoPt onto a surface at room temperature from an aqueous solution. One part of the peptide nucleates and controls the growth of CoPt nanoparticles from solution, and the other part binds to SiO2. A native silicon oxide surface is functionalized with a high loading of the DAP using microcontact printing. The DAP biotemplates a monolayer of uniformly sized and shaped nanoparticles when immobilized on the silicon surface. X-ray diffraction shows that the biotemplated nanoparticles have the L10 CoPt crystal structure, and magnetic measurements reveal stable, multiparticle zones of interaction, similar to those seen in perpendicular recording media. This is the first time that the L10 phase of CoPt has been formed without high temperature/vacuum treatment (e.g., annealing or sputtering) and offers a significant advancement toward developing environmentally friendly, biotemplated materials for use in data storage