Strong Band Gap Blueshift in Copper (I) Oxide Semiconductor via Bioinspired Route

Semiconductors have numerous applications in both science and technology. Several methods have been developed to engineer their band gap, which is one of the most important parameters of semiconductors. Here, it is shown that the incorporation of various amino acids into the crystal lattice of copper (I) oxide, akin to the way living organisms incorporate organic macromolecules into minerals during biomineralization, leads to significant shrinkage in the volume of the host unit cell and a strong blueshift in the band gap of up to ≈18%. In examining the potential location of the bio‐organic molecules within the inorganic host's lattice, a very good fit between the proposed model of incorporation and experimental findings is found. The bioinspired phenomenon of band gap widening is thought to be attributable to the void‐induced quantum confinement effect, even though observed in micrometer‐sized crystals. This hypothesis is supported by developing a tight‐binding model that is found to fit well with the experimental data. The outcome of this research could profoundly impact the fields of light‐emitting and spin‐based devices as well as opens up a new bioinspired route to tune the band gap of semiconductors.     

Cobalt,nitrogen-doped carbons as catalysts for sodium borohydride hydrolysis: role of surface chemistry

Journal of Materials Science - The development of an effective method for modifying a carbon surface in order to improve its activity and electronic properties for the electrocatalysts creating is...     

Effect of Hydrogen Bonding on a Value of an Open Circuit Potential of Poly-(3,4-ethylenedioxythiophene) as a Beneficial Mode for Energy Storage Devices

Poly(3,4-ethylenedioxythiophene) is one of the semiconducting polymers that has attracted attention as electroactive materials for many different applications such as electrochromic devices, light-emitting diodes, biosensors, and supercapacitors. The fundamental understanding of the origin of its energy storage ability will lead to the proper design of such devices. Generally, the charge storage in supercapacitors is due to the formation of an electrical double layer and/or redox reactions. Recently, it is shown that the formation of cation radicals in PEDOT is induced by the hydrogen-bond formation between formic acid and polymer during electrochemical polymerization. The induced cation radicals play a major role in the charge storage ability of PEDOT, as studied in the current work. Furthermore, the presence of hydrogen bonds in PEDOT leads to the stable in time open circuit potential of 900 mV. This new knowledge leads to the designing of a symmetrical supercapacitor based on PEDOT as active material where hydrogen-bonds play a crucial role in the improved performance of the device.     

Periodic Arrays of Diamond‐Shaped Silver Nanoparticles: From Scalable Fabrication by Template‐Assisted Solid‐State Dewetting to Tunable Optical Properties

Periodic arrays of anisotropic silver nanoparticles having peculiar optical properties are fabricated at a macroscopic scale. The proposed scalable method is based on temperature‐assisted solid‐state dewetting of a continuous thin layer deposited on a silica substrate patterned by the nanoimprint technique. The resulting nanoparticles are shaped like diamonds and are half‐embedded into the patterned silica. A period‐dependent optimum in film thickness for the quality of spatial organization is found and discussed in terms of thermodynamics and, for the first time, in terms of the role of grains in the dewetting process. The optical properties of the arrays are driven by not only simply the particle shape but also the lattice period and the degree of order. A surface lattice resonance that disperses with the underlying period is evidenced experimentally and confirmed by optical simulations. The opportunity to fabricate and tune such an assembly of plasmonic particles on transparent substrate opens interesting perspectives for not only fundamental photonics but also potential optical applications.     

Mechanical properties with respect to water content of gelatin films in glassy state

Changes on the structural and molecular level of gelatin films induced by hydration below 25±3% water content (glass–rubbery transition at ambient temperature) were identified with DSC and FTIR spectroscopy. Three main stages of hydration were distinguished: (I) water bound by high-energy sorption centres; (II) structural water; (III) polymolecular layer water. The mechanical behaviour of gelatin films at each stage of hydration was characterized. Relaxation of the films during hydration was taken into account in the analysis of results. Hydrated gelatin films were characterized as brittle below the glass–rubbery transition at ambient temperature, however some improvement of mechanical properties related to a higher renaturation level was showed between 7 and 14% of water content in stage II (structural water).     

Optimising anti-spam filters with evolutionary algorithms

This work is devoted to the problem of optimising scores for anti-spam filters, which is essential for the accuracy of any filter based anti-spam system, and is also one of the biggest challenges in this research area. In particular, this optimisation problem is considered from two different points of view: single and multiobjective problem formulations. Some of existing approaches within both formulations are surveyed, and their advantages and disadvantages are discussed. Two most popular evolutionary multiobjective algorithms and one single objective algorithm are adapted to optimisation of the anti-spam filters’ scores and compared on publicly available datasets widely used for benchmarking purposes. This comparison is discussed, and the recommendations for the developers and users of optimising anti-spam filters are provided.     

Forming carbonitride coatings on titanium by thermochemical treatment with C-N-O-containing media

The formation of TiC_xN_y coatings on titanium alloys through thermochemical treatment of graphite in nitrogen was investigated in this study. The presence of oxygen in saturating media was found to lower the nitrocarburizing temperature from 1,100°C to 850°C. Two methods to accumulate oxygen in a saturating medium have been proposed: using oxygen-containing nitrogen or oxygensaturated graphite. The sequence of stages of carbonitride formation in the Ti-C-N-O system is explained in this paper.