Issue 4

A review on humidification membrane materials for fuel cells 

Russell Borduin; Alexander J. Headley; Wei Li; Dongmei Chen

Advanced Materials Letters, 2018, Volume 9, Issue 4, Pages 225-233
DOI: 10.5185/amlett.2018.1886

Polymer electrolyte membrane (PEM) fuel cells have the potential to replace fossil fuel sources in both automotive and auxiliary stationary power generation applications. Increased implementation of fuel cells would decrease dependence on oil and reduce greenhouse gas emissions. However, a major obstacle preventing widespread adoption of fuel cells is cost. The two largest contributors to fuel cell costs are platinum catalyst loading and fuel cell power density. The general strategy for increasing power density and decreasing costly catalyst loading remains unchanged regardless of the catalyst used, i.e., to run the fuel cell at higher temperatures and pressures. Present-day automotive fuel cells typically operate over a temperature range of 50-90°C and pressures up to 3 atm. Increasing temperature and pressure allows for reduced catalyst loading and higher voltage output from the fuel cell. These harsher operating conditions require new membrane materials for thermal and water management. This review provides a summary of a variety of humidification membrane materials, both existing and under development, in order to identify a humidification membrane material capable of operating at higher temperature and pressure conditions to increase fuel cell efficiency and lower the humidification. 

Ternary hybrid electrode material based on polyaniline/carbon nanohorn/TiO2 with high performance energy storage capacity

Sandip Maiti; Ranadip Bera;Bhanu B. Khatua; Sumanta K. Karan; Amit K. Das

Advanced Materials Letters, 2018, Volume 9, Issue 4, Pages 234-240
DOI: 10.5185/amlett.2018.1763

Renewable energy is very much demanding in modern time. Herein, we have discussed energy storage performance of polyaniline (PANI) and carbon nanohorn (CNH) decorated titanium dioxide (TiO2) nanoparticle, high-performance electrode material. This high-performance energy storage material was prepared through simple and cost-effective method via in-situ polymerization of aniline in presence of CNH and TiO2 nanoparticles. Thus, as prepared active electrode material provides high specific capacitance value of 1068 F/g at current density of 3 A/g. The existence TiO2 nanoparticle in the ternary hybrid leads to enhancement of capacitance value through synergistic effect compared to the pure components (e.g., PANI and CNH are 335 F/g and 240 F/g, respectively at same current density). As morphological analysis says, TiO2 nanoparticles are observed to be coated by CNH nanofiller and PANI fiber in the hybrid, which plays a key role to enhance the capacitance value of hybrid making it highly promising electrode material for energy storage in the next-generation power supply. 

Enhanced microwave absorption property of aluminum composites using fly ash derived cenosphere  

Rajeev Kuma; Saroj Kumari;S. Das; D.P. Mondal; Shyam Birla; Amit Vishwakarma; Anisha Chaudhary

Advanced Materials Letters, 2018, Volume 9, Issue 4, Pages 241-248
DOI: 10.5185/amlett.2018.1760

In the present investigation, influence of micronsize cenosphere particles derived from fly ash on the properties of aluminum composites was investigated. Aluminum-cenosphere (AC) composite was fabricated by modified stir casting technique. The mechanical and electromagnetic interference (EMI) shielding properties of AC composites were investigated. The obtained composites with cenosphere (+100 µm) loading demonstrate the excellent compressive strength of 251.3 MPa. This enhancement is due to the smaller size of cenosphere size provides the finer surface of the cenosphere. The addition of cenosphere in aluminum matrix improved dielectric and microwave absorption properties of composites in X band frequency region (8.2-12.4 GHz). The AC composites possess good EMI shielding effectiveness of -32.7 to -44.3 dB with 30% loading of cenosphere with various sizes (+212, +150 and +100 µm). The incorporation of lower size cenosphere (+100µm) in aluminum matrix significantly increases the interfacial polarization which leads to a higher absorption EMI shielding effectiveness (SE) of -31.1 dB at 2.0 mm thickness. This technique is very simple, economical and highly reproducible, which may facilitate the commercialization of such composite and it can be used as microwave absorbing materials in defense and aerospace applications.

Template-assisted fabrication of tunable aspect ratio, biocompatible iron oxide pillar arrays

Ryan Chang Tseng; Ching-Wen Li; Gou-Jen Wang

Advanced Materials Letters, 2018, Volume 9, Issue 4, Pages 249-257
DOI: 10.5185/amlett.2018.1842

The extensive use of iron oxide nanomaterials in biomedical applications has prompted the development of a novel substrate for evaluating cell behaviour. This study examines the fabrication of tuneable length iron oxide pillar arrays using the porous nanochannels of anodic aluminium oxide membranes, and evaluates the biocompatibility of the substrate. The electroformed iron pillars were found to conform to the template channels with slightly larger iron oxide pillar diameters, due to the presence of an oxide shell. The biocompatibility was then confirmed with WST-1 proliferation and viability assay of cultured KT98 murine neural/progenitor stem cells on the surface of the pillar array; with no significant difference observed between viable cells after seven days of culture on iron oxide pillars, flat iron oxide, and tissue culture polystyrene. The physical properties of the pillar arrays were linked to the adhesion and spreading of the cells, and found that cells cultured on the pillar arrays had reduced spreading in comparison to tissue culture polystyrene control. In addition, it was found that protein expression was unaffected by culture on iron oxide substrates. The results of this study indicate that iron oxide pillar arrays are suitable to extended cell studies.

Carvedilol drug-organo montmorillonite nanocomposites: Preparation, characterization and drug release studies

V. M. Santhini; S.P.Suriyaraj;H. Bava Bakrudeen; M. Sugunalakshmi; S.P.Suriyaraj and H. Bava Bakrudeen

Advanced Materials Letters, 2018, Volume 9, Issue 4, Pages 258-265
DOI: 10.5185/amlett.2018.1881

In this study the Carvedilol drug-organo modified montmorillonite (CV/OMMT) nanocomposites were prepared using different organo modified MMT (Nanomer 1.31PS, Nanomer 1.34TCN, Nanomer 1.44P) through solution intercalation method. The degree of intercalation, microstructure and morphology of the nanocomposites were characterized by FTIR spectroscopy, thermogravimetric analysis and transmission electron microscopic analysis. The purpose of this study is to elaborate the drug loading capacities and drug release behaviours of different organo modified MMT (OMMT) on enhancing their swelling in aqueous medium. The in vitro drug release profiles from the CV/OMMT nanocomposites at pH 1.2 and pH 7.4 were also assessed. Simultaneously, the drug release kinetic parameters for all the CV/OMMT nanocomposites at both gastric and intestinal pH have also been discussed with established mathematical models. 

Mechanical properties of hydroxyapatite scaffolds produced by gel-casting and combination gel-casting/polymer foams infiltration

Jazmín I. González; Diana M. Escobar; Claudia P. Ossa

Advanced Materials Letters, 2018, Volume 9, Issue 4, Pages 266-274
DOI: 10.5185/amlett.2018.1981

Hydroxyapatite is one of the appropriate materials for hard tissue engineering because it is the inorganic structural constituent of bones and teeth, and hydroxyapatite has been evaluated to compare the mechanical properties, processing as scaffolds to evaluate the influence of porosity, since the elastic modulus of material is influenced by the porosity, it is essential to establish a relationship between the two characteristics to obtain a material with optimum conditions for its implantation. The main objective of this research was to study the mechanical properties of hydroxyapatite scaffolds using compression and nanoindentation tests. The scaffolds were manufactured by gel-casting and gel-casting combined with foam polymer infiltration, in both cases 40 and 50% solids and three different monomers were used. The samples obtained by gel-casting exhibited a compressive strength between 0.93 and 6.15 MPa, an elastic modulus between 11.46 and 27.27 GPa; some of these scaffolds showed very similar values to human trabecular bone reported. In addition, samples produced by gel-casting combined with foam polymer infiltration, it was found that compressive strength was between 0.05 and 0.12 MPa, the elastic modulus between 1.61 and 6.24 GPa, concluding that the gel-casting produces scaffolds with closest to trabecular bone.

Synthesis, characterizations, and comparative study of electro-optical properties of indole-based squaraine sensitizers as efficiency to enhancing dye-sensitized solar cells

Sultan A. Al-horaibi; S.T. Gaikwad; Anjali S. Rajbhoj

Advanced Materials Letters, 2018, Volume 9, Issue 4, Pages 275-283
DOI: 10.5185/amlett.2018.1457

Squaraine dyes (SQ) have acquired sufficiently great attention as dye-sensitized solar cell (DSSCs) materials. In the present study, we have synthesized and characterized of two novel symmetrical sensitizers dyes for dye-sensitized solar cells which contain electron withdrawing (−COOH) group with long alkyl ester chain (SQ1) and another without encoring group (SQ2). We have investigated the structural, electronic, photo-electrochemical, and charge transport properties of two SQ1& SQ2 indole-based squaraine dyes. The ground state geometry has been computed by applying density functional theory (DFT). The excitation energy and the oscillator strength were calculated by using time-dependent (DFT-TD) at DFT/B3LYP/6-31G** level of theory. We have focused and study on the frontier molecular orbitals (HOMO and LUMO), electron injection (ΔG inject ), light harvesting efficiency (LHE), open-circuit voltage (Voc), relative electron injection (ΔGr inject ), and short-circuit current density (Jsc). The effect of-COOH as (acceptor) and -OCH3 (donor) groups on SQ1 and SQ2 were investigated. The factors affecting, ΔG inject , LHE, Voc and Jsc revealed that SQ1 would be more favourable to enhance the performance of DSSCs. The theoretical calculations and absorbance results show that the electron density of LUMO of SQ1 is delocalized in the whole chromophore, leading to strong electronic coupling between SQ1 and TiO2 surface. So, the SQ1 sensitized solar cells exhibit better photovoltaic performance. 

Assembly and characterization of ZnO nanoparticles for Grätzel's solar cells  

Glécia V. S. Luz; Wang. S. Hui; Renata C. Roncoleta; Pedro H. O. Nogueira; Lourdes M. Brasil; Pilar Hidalgo

Advanced Materials Letters, 2018, Volume 9, Issue 4, Pages 284-290
DOI: 10.5185/amlett.2018.1599

This research aimed to build hybrid solar cells, based on Grätzel method. We used the Polyethylene Terephthalate (PET) polymer as a substrate containing a layer of Indium Tin Oxide (ITO). Films of ZnO nanoparticles (ZnO NPs) synthesized by Pechini Method, and four different dyes were tested: Congo Red (CR), Bromocresol Green (BG), Acridine Orange (AO) and a Ruthenium Complex (RC). ZnO NPs were analyzed by XRD, which generated peaks corresponding to hexagonal wurtzite crystalline structure. We also conducted analysis by UV–Vis. Spectroscopy and Transmission Electron Microscope (TEM). Rietveld analysis determined the crystal size of 115.23 ± 28.16 nm. The deposition of ZnO and dye thin films were made through spin-coating. The electrical properties of the formed films were characterized with Van der Pawn method. Efficiency in converting light in electricity under an OSRAM 20W light bulb was tested after the devices were built. The smaller sheet resistance results were obtained for material containing: PET/ITO/ZnO/CR and PET/ITO/ZnO/AO. As expected, the best open-circuit voltage (Voc) results reached were 64 and 73 mV to CR and AO, respectively. Therefore, the results demonstrated satisfactory interaction between the ZnO-Dye-Electrolyte layers.

Development of a Co-20Cr alloy for potential biomedical applications

Ana Ramirez-Ledesma; Hugo Lopez F; Julio Juarez-Islas

Advanced Materials Letters, 2018, Volume 9, Issue 4, Pages 291-295
DOI: 10.5185/amlett.2018.1586

A Co-20 wt. Cr alloy was vacuum induction melted and cast into a wedge shaped copper mold. The resultant microstructures were investigated from sections obtained longitudinally and centrally in the plane normal to the diverging wedge faces. The aim of this work was to produce a microstructure free of interdendritic segregation with minimal or no intermetallic precipitates and suitable for biomedical implant applications. The as-cast microstructure consisted predominantly of columnar dendrites. In particular, the presence of athermal HCP e-martensite and the metastable FCC γ-Co phase were identified by X-ray diffraction means and scanning electron microscopy. It was found that the exhibited volume fraction of athermal e-martensite was over 90 wt. %. In addition, a heat treating below the γ/e transition temperature led to transformation of the athermal e-martensite into a stress-relieved isothermal one.  In turn, the resultant tensile properties, ductility and fracture mode of the alloy after the heat treatment exhibited significant changes. Finally, preliminary tests in artificial saliva indicated that the heat-treated alloy possesses appreciable corrosion resistance when compared with other Co-alloys, making it an ideal candidate for dental implants. 

Formation of carbon sp3 hybridization bonds in local electric fields of composites “polymer-CNT”

Liudmyla Karachevtseva; Mykola Kartel; Wang Bo; Yurii Sementsov; Viacheslav Trachevskyi; Oleg Lytvynenko; Volodymyr Onyshchenko

Advanced Materials Letters, 2018, Volume 9, Issue 4, Pages 296-300
DOI: 10.5185/amlett.2018.1964

Carbon nanotubes are among the most anisotropic materials known and have extremely high values of Young's modulus. The possibilities to enhance the properties of nanostructured surfaces were demonstrated on “polymer-multiwall carbon nanotube” composites. Influence of sp < sup > 3 hybridization bonds on polymer crystallization and strengthening was investigated in composite films of polyethyleneimine, polypropylene and polyamide with multiwall carbon nanotubes. It was established that the effective way to enhance the strength properties of “polymer-multiwall carbon nanotube” composites is the composite crystallization and sp < sup > 3 C-C tetrahedrons organization between nanotubes supported by resonance γω(C?)? and γω(CH2) vibrations in the intrinsic electric field 6×10 3 V/cm between nanotube and polymer matrix. Tensile strength for polyamide-6 composites at 0.25% CNT increases 1.7 times and tensile deformation – 2.3 times.

XPS analysis of the skin treated by microplasma

Jaroslav Kristof; Hideto Miyamoto; Marius Blajan; Kazuo Shimizu

Advanced Materials Letters, 2018, Volume 9, Issue 4, Pages 301-305
DOI: 10.5185/amlett.2018.1966

A microplasma electrode was used for skin treatment using argon, oxygen, nitrogen or ambient air. The presence of various particles is important for the interpretation of the microplasma effect on the skin. The production of long living particles was detected by an FTIR spectrometer and the presence of air between the sample and the electrode was monitored by the O2 monitor. In the case of gases other than air, we concluded that the concentration of processing gas is at least 99.5 %. The epidermal layer of pig skin was used for observing changes caused by microplasma treatment. The XPS spectra of carbon and oxygen were analysed.

Plasmonic sensor for evaluation of the neuropeptides level in the human fluids  

Alexander Axelevitch

Advanced Materials Letters, 2018, Volume 9, Issue 4, Pages 306-310
DOI: 10.5185/amlett.2018.1983

One of important problems in the diagnostic and treatment of the patient’s states is operative evaluation of a type and amount of various neuropeptides secreted into the blood in human organisms. Due to similar structures and molecular weight of neuropeptides, their identification and individual evaluation is very complicated and not always consistent. For example, such substances as Oxytocin and Argenine-Vasopressin act differently on the human body, however they are look similar. The main purpose of the present work is to create a non-destructive sensor enabling operatively differentiate and evaluate the quantity of various neuropeptides existing in the human fluids such as sweat, saliva or blood. Through the experimental and theoretical efforts, it was found that the proposed goal may be solved using nanostructured semiconductor sensor producing the plasmon-polaritons in the near ultra-violet range. The frequency and intensity of generated plasmons are affected by material composition of the studied analyte.