Issue 8

Various surfactants for 0 – 3 dimensional nanocarbons: Separation, exfoliation and solubilization

Naoki Komatsu

Advanced Materials Letters, 2019, Volume 10, Issue 8, Pages 520-523
DOI: 10.5185/amlett.2019.2278

Nanocarbons are carbon allotropes with nanometer scale and comprised mainly of 0 – 3 dimensional (0D – 3D) forms; fullerenes (0D), carbon nanotubes (1D), graphene (2D), and nanodiamond (3D). In our group, various surfactants with appropriate size and shape have been developed for the nanocarbons. In order to separate the fullerenes, bowl-shaped surfactants were designed and synthesized to accommodate the 0D spherical nanocarbon, giving C70 selectively as precipitates. On the other hand, gable- and bracket-shaped surfactants formed stable complexes with 1D tubular nanocarbons, dispersing carbon nanotubes with specific diameter, handedness and/or metallicity selectively in solution phase. The flat surfactants worked as an exfoliant and dispersant for graphite in both wet and dry processes; sonication and ball milling, respectively. They gave graphene composites with high concentrations and yield in aqueous solution and low-boiling point organic solvents. The hyper-branched polymer named polyglycerol coated the nanodiamond surface covalently through ring-opening polymerization of glycidol. The chemisorped polymer gave large hydrophilicity to the nanodiamond, dispersing it stably in aqueous solutions such as water and phosphate buffer as well as polar organic solvents such as methanol. Copyright © VBRI Press.

Polypyrrole based biofunctional composite layer for bioelectrocatalytic device system

Yilkal D. Sintayehu; H. C. Ananda Murthy

Advanced Materials Letters, 2019, Volume 10, Issue 8, Pages 524-532
DOI: 10.5185/amlett.2019.2279

The involvement and development of intelligent polymers in enzymes as a catalyst have been interesting to develop processes that are environmentally benign, energy efficient, and selective towards their specific molecular applications. Polypyrrole based enzyme nanocomposites represents a continuous considerable redox organic polymer that have been increased in electromechanical devices in advance for surface functionalization. This review addresses the fundamental concepts of polypyrole and its composites role for enzyme immobilizing functioning and its bio functional bioelectrocatalytic system operating principle in biosensor and biofuel cells as well as its involvement in electron transfer mechanism as a bio electrode to create an advanced bioelectronics device from power generating system to extreme analyte detecting system. Copyright © VBRI Press.

Innovative Graphene-PDMS sensors for aerospace applications 

Filomena Piscitelli; Gennaro Rollo; Fabio Scherillo; Marino Lavorgna

Advanced Materials Letters, 2019, Volume 10, Issue 8, Pages 533-538
DOI: 10.5185/amlett.2019.9903

For aerospace morphing and deployable applications, the use of PDMS-based sensors is crucial because they are characterized by easy application on large surfaces, light design, very large deformations, and durability in harsh environmental conditions. In this contest, the goal of the present work is to manufacture innovative, highly deformable, piezoresistive sensors, manufactured by using a simplified and scalable method for the applications on large-area, such as the airplane wings. To this end, an ad-hoc polymeric matrix was designed by crosslinking Polydimethylsiloxane (PDMS) oligomers OH terminated with siloxane domains, obtained from hydrolysis and condensation of tetraethyl orthosilicate (TEOS). In particular, the solution of siloxanes domains precursors contributes to lower the viscosity without any solvents and to create, after curing, a fine crosslinked system which could withstand high deformation. Nanocomposites with graphene (6 - 15 wt%) were prepared by dispersing the filler into the polymeric precursor by adopting both magnetic stirring and sonication. Regardless the dispersion method and the filler concentration, few-layers of graphene coexists with large aggregations, and the electrical conductivity and the Gauge Factor increase as the graphene content increases. It was found that the graphene filler tends to hinder the evaporation of solvents developed during the crosslinking reactions, generating porosity and enhancing conductivity. A better filler dispersion obtained through sonication reduces the conductivity. All nanocomposites show a good linear relationship between the strain and the relative electrical resistance change, since the non-linearity remains below the 5%, and quite no-drift can be observed in a wide operative range. Copyright © VBRI Press.

Effect of hot drawing process and carbonization temperature in electrochemical behavior of electrospun carbon nanofibers

Andrés Felipe Zapata-González; Julieth Carolina Cano-Franco; Mónica Lucía Álvarez-Láinez

Advanced Materials Letters, 2019, Volume 10, Issue 8, Pages 539-544
DOI: 10.5185/amlett.2019.9902

Due to the problems that exist on several systems that store energy, such as low energy density, low storage capacity and limited useful life; carbon nanofibers (CNFs) appear as an alternative to remedy such problems, due to their excellent properties, such as high electrical conductivity, high surface area and flexibility. However, there are some alternatives to reinforce their properties and optimize their application in energy storage systems. In this way, in our work, we look for an alternative to increase the capacitive properties of the CNFs. The hot drawing treatment was applied to the CNFs to improve their electrochemical performance for supercapacitor applications. First, non-woven polyacrylonitrile (PAN) membranes were manufactured by electrospinning, and then, the hot-drawing treatment was applied to promote molecular alignment. Prepared and stretched PAN membranes were carbonized at different temperatures to obtain CNFs. According to the applied hot drawing treatment and the increase in temperature, the crystalline structure of the CNFs was improved, which led to an increase in the electrochemical properties of the CNFs. The specific capacitance of the CNFs was increased by 88% when hot drawing process was applied and carbonized at 1000°C, compared to the sample without the application of the stretching treatment. Copyright © VBRI Press.

Chemical Reactivity and Electronical Properties of Graphene and Reduced Graphene Oxide on Different Substrates

E. Celasco

Advanced Materials Letters, 2019, Volume 10, Issue 8, Pages 545-549
DOI: 10.5185/amlett.2019.2204

The chemical reactivity and the electronical properties variation of graphene (G) supported on Ni(111) and of the reduced Graphene Oxide (rGO) will be described thanks to the framework of University of Genoa and Polytechnic of Turin. We will present the main results obtained on the reactivity, towards CO, of pristine graphene grown on Ni(111). Single layer graphene films are grown by ethene dehydrogenation on Nickel, under different experimental conditions, and the system is studied in-situ by X-ray Photoemission and High-Resolution Electron Energy Loss Spectroscopies before and after CO exposure at 87 K and at room temperature. The main results were: the best CO reactivity in the top-fcc configuration of graphene on Ni(111), at low temperature. the higher reactivity occurs in the case of minimum percentage of contaminant or Ni2C still present during the grown process. a reactivity toward CO at room temperature on graphene with punctual controlled defects by sputtering, with possible applications e.g., gas sensing. More applicative aspect is the modification of GO in rGO, by UV based process. During the reduction, electrical properties is improved, opening possible application in the ink-jet printing mechanism as conductive printing system, coating or in the functionalization of G. Copyright © VBRI Press.

Laser Raman micro-spectroscopy as an effective non-destructive method of detection and identification of various sp2 carbon modifications in industry and in nature

Sergey S. Bukalov; Larissa A. Leites; Rinat R. Aysin

Advanced Materials Letters, 2019, Volume 10, Issue 8, Pages 550-562
DOI: 10.5185/amlett.2019.2268

Raman micro-spectroscopy is recommended as an effective non-destructive method of detection and identification of various sp < sup > 2  carbon modifications, each being characterized by its own specific set of spectral band parameters (frequencies, intensities, half-widths and contours). The results of the authors obtained for numerous industrial sp < sup > 2 carbon samples (highly ordered and disordered graphites, turbostratic graphite, glassy carbons, carbon fibers, amorphous sp < sup > 2 carbon, nanotubes) as well as for natural species (terrestrial natural graphites and shungites, Lunar soil, meteoritic matter) are summarized, analyzed and compared. Literature data are also considered and discussed. The results show that the man-made advanced materials contain the same sp < sup > 2 carbon modifications as have been found in Nature (on Earth, Moon and in cosmic space). Copyright © VBRI Press.

Electrochemical promotion of ammonia synthesis with proton-conducting solid oxide fuel cells

Chien-I Li; Akio Oikawa; Fumihiko Kosaka; Junichiro Otomo

Advanced Materials Letters, 2019, Volume 10, Issue 8, Pages 563-568
DOI: 10.5185/amlett.2019.2259

Direct electrochemical synthesis of ammonia was performed using proton-conducting solid oxide fuel cells. In this study, we investigated the effect of electrode potential on the reaction kinetics of ammonia formation with Fe- and Ru-based catalysts in detail. The cell configuration was Pt|BaCe0.9Y0.1O3 (BCY)|K-modified Fe or Ru-BCY. The ammonia formation rate of K-Ru was higher than that of K-Fe at the rest potential. However, the ammonia formation rate significantly increased by cathodic polarization for the Fe catalyst, and it showed a linear increase for the Ru catalyst, i.e., the ammonia formation rate for K-Fe significantly increased from the rest potential by several hundred times to -1.2V at 700 o C, but K-Ru showed only a five times increase. The results suggest that the addition of K into Fe-BCY and cathodic polarization can improve the ammonia formation rate because of the promotion of bond dissociation of the N molecule on the Fe catalyst. The present work provides a hint for efficient ammonia formation and contribute to further development of ammonia electrochemical synthesis with proton-conducting solid oxide fuel cells. Copyright © VBRI Press.

Biomimetic surfaces with hierarchical structure using microsized texture and nanosized Cu particles for superhydrophobicity

Liguo Qin; Hao Yang; Xinan Feng; Mahshid Hafezi; Mawignon Fagla Jules; Bin Liu; Hui Zhang; Guangneng Dong; Yali Zhang

Advanced Materials Letters, 2019, Volume 10, Issue 8, Pages 569-573
DOI: 10.5185/amlett.2019.2252

Currently, there is a huge demand for the application of superhydrophobic surface in industrial and marine equipment. In this investigation, the hydrophobicity of Q235 steel surface was achieved by implementing micro-patterns on the substrate using laser surface texturing and deposition of nano-copper particles. By controlling the movement of the laser spots, different controlled textures at microscale were fabricated. Via the chelation between the copper species and the catechol moieties on polydopamine (PDA), nano copper was decorated to form the multi-level structure. The surface microstructure, topographies, chemical component and wettability of as-prepared superhydrophobic surface were analyzed systematically. Based on the models built by Wenzel and Cassie–Baxter, the effect of micro texture on contact angle was discussed. This method is expected to have many potential applications including antibacterial materials for the protection of marine equipment. Copyright © VBRI Press.

Enhancement the properties of high and low-density polyethylene membranes by radiation grafting process

Hussein Oraby; Mohamed A. Elsayed; Mohamed Gobara; Magdy Senna

Advanced Materials Letters, 2019, Volume 10, Issue 8, Pages 574-585
DOI: 10.5185/amlett.2019.2287

In this work, trials have been made to prepare different graft copolymers by direct irradiation grafting technique and evaluating their reverse osmosis properties. The acrylic acid monomer was grafted onto two improper polymers (low and high-density polyethylene) by means of gamma-ray as a motivator. The optimum conditions of preparation were using acetone as a solvent, monomer concentration 30% (wt/wt), using anhydrous ferric chloride as an inhibitor with optimum concentration 0.1% (wt/wt) and irradiation dose 20 KGy. Mechanical, rheological and thermal properties of the prepared membrane were also investigated. The prepared grafted membranes showed significant results in RO desalination method using underground saline water from Abo Swear, Ismailia, Egypt. Copyright © VBRI Press. 

Synthesis of 9-Aminoacridine and its Application as an Anode Material for Aqueous Rechargeable Lithium–ion Batteries

Madhushree M. Ravikumar; Vijeth R. Shetty; Suresh G. Shivappa

Advanced Materials Letters, 2019, Volume 10, Issue 8, Pages 586-594
DOI: 10.5185/amlett.2019.9909

Two organic compounds namely Acridine (ACD) and 9-aminoacridine (ACD-NH2) have been investigated as electrode materials for an aqueous rechargeable lithium-ion battery (ARLIB) applications. The electrochemical investigations reveal that the active species act as anodes in ARLIB systems. In this regard, nitrogen group act as redox center and undergo electrochemical reaction with Li-ions during charge and discharge process. The synthesis of 9-amonoacridine is done by standard method called chichibabin reaction. Amination of ACD enhances the electrochemical behaviour of the molecule. To improve the electrochemical performances of ACD & ACD-NH2, graphene is used as an additive for ARLIB system. The decorated molecules such as decorated Acridine (dACD) and decorated 9-aminoacridine (dACD-NH2) showed improved electrochemical performance as compared with ACD & ACD-NH2. The decoration is of great importance concerning capacity, reversibility and stability of cycling behavior during charge and discharge processes. Charge/discharge tests show that ACD, ACD-NH2, dACD, and dACD-NH2 have achieved initial discharge capacities of 119, 122, 149 and 220 mAh g -1 respectively at a current density of 0.2 mA. The good cyclic performance and agreeable discharge capacity of the cell signifies the application of dACD-NH2 as anode material for ARLIB system. Copyright © VBRI Press.

Facile synthesis of novel tough and highly flexible biodegradable membranes for water microfiltration

Ahmed H. Ibrahim; Amina A. F. Zikry; Rasha A. Azzam; Tarek M. Madkour

Advanced Materials Letters, 2019, Volume 10, Issue 8, Pages 595-603
DOI: 10.5185/amlett.2019.2230

Microporous polymeric membranes have found great applications in the area of water desalination and wastewater treatment, tissue engineering, drug delivery, and bone regeneration. The ability to create micro-size pores within a polymeric membrane allows for cavity formation that could form channels through which substances may permeate or percolate easily. The majority of these applications though, require micro-size porous membranes with small pore size and narrow pore-size distribution as to allow the control of the permeating substances or tissues. In the current work, an intricate and precise method was developed to generate micro-size porogen salt crystals with controlled micro-size distribution, which is then mixed with a specific biodegradable polymeric blend designed to offer both toughness and high flexibility for the production of microfiltration biodegradable membranes that can withstand the high pressures of large volumes of industrial wastewater undergoing filtration treatment. After casting, the porogen crystals are washed away rendering membranes with well-distributed micro-scale cavities. Using salt porogens offers a great advantage of no contamination to the environment since all salt particles are simply washed away. The ingenuity of this technique is that it allows the filtration of the wastewater at low or no pressures. Copyright © VBRI Press.

Investigating the possibility of using acetic acid in place of HF in chromium-benzenedicarboxylates (MIL-53 and MIL-101) synthesis applicable for CO2 adsorption

Fariba Soltanolkottabi; Mohammad Reza Talaie; Seyedfoad Aghamiri; Shahram Tangestaninejad

Advanced Materials Letters, 2019, Volume 10, Issue 8, Pages 604-609
DOI: 10.5185/amlett.2019.2280

The present study concerns chromium benzenedicarboxylates MIL-53 and MIL-101 hydrothermal syntheses utilizing acetic acid, and their capabilities for CO2 adsorption. The effect of the parameters such as reaction time, reaction temperature, water concentration, and acetic acid content on adsorption characteristics of these metal-organic frameworks (MOFs) is investigated using L8 Taguchi experimental design. In synthesized MIL-101, with adding 1 acetic acid equivalent with respect to Cr, reaction time and temperature have been reduced from 24 h and 483 K to 6 h and 463 K. Also, the CO2 adsorption capacity has been measured by a volumetric method. The results have revealed that adding acetic acid and reducing water in the reaction mixture results in converting MIL-101 to MIL-53 which tends to an increase in CO2 adsorption. With regard to reaction conditions, the results show that MIL-53 and MIL-101 have the maximum CO2 adsorption capacities of 17.5 and 11.0 mmolg -1 at 3.5 bar and 299.2 K, respectively. Copyright © VBRI Press.