Extended Surface Area Research Articles

Study of Chemical and Morphological Transformations during Ni2Mo3N Synthesis via an Oxide Precursor Nitration Route

Chemical and morphological transformations during Ni2Mo3N synthesis were studied in this work. Nitride samples were synthesized from oxide precursors in H2/N2 flow and were analyzed by thermogravimetry, X-ray diffraction analysis, scanning electron microscopy, and energy dispersive X-ray spectroscopy methods. In addition, physical and chemical adsorption properties were studied using low-temperature N2 physisorption and NH3 temperature-programmed desorption. It was shown that nitride formation proceeds through a sequence of phase transformations: NiMoO4 + MoO3 → Ni + NiMo + MoO2 → Ni + NiMo + Mo2N → Ni2Mo3N. The weight changes that were calculated from the proposed reactions were in agreement with the experimental data from thermogravimetry. The morphology of the powder changed from platelets and spheres for the oxide sample, to aggregates of needle-like particles for the intermediate product, to porous particles with an extended surface area for the nitride final product. The obtained results should prove useful for subsequent Ni2Mo3N based catalysts production process optimization.

Nano-magnetite/ionic liquid crystal modifiers of carbon nanotubes composite electrode for ultrasensitive determination of a new anti-hepatitis C drug in human serum

Direct-acting antivirals (DAAs) are promising redeemer for patients suffering from Hepatitis C virus (HCV). From the clinical point of view, it is crucial to determine the level of a newly introduced drug of the DAAs-class known as daclatasvir (DAC) in an effective and simple method. A newly designed conductive composite was fabricated based on manual casting of thin layer of ILC sandwiched between two layers of multi-walled carbon nanotubes followed by a layer of nano-magnetite iron oxide (CNTs/ILC/CNTs/FeNPs). The ILC allowed good interaction with CNTs that result in highly ionic and electronic composite with extended surface area for assembling the magnetite FeNPs. The composite is used as direct sensor for the determination of DAC. Compared to glassy carbon-CNTs (GC/CNTs), (CNTs/ILC/CNTs/FeNPs) showed five folds increase in the current for the oxidation of DAC. The sensor exhibited excellent electro-catalytic activity toward DAC determination in human serum in a wide concentration range 0.003 μmol L−1 to 15 μmol L−1. The detection limit and correlation coefficient are 0.383 × 10−10 mol L−1 and 0.993, respectively in the low concentration range 0.003–0.1 μmol L−1. The CNTs/ILC/CNTs/FeNPs sensor has been applied for the simultaneous determination of DAC with acyclovir (ACY) antiviral drugs and in presence of interfering compounds: ascorbic acid (AA), uric acid (UA), dopamine (DA) and paracetamol (APAP). The method presents good sensitivity and stability appropriate to be employed in quality control and routine quantification of drug in pharmaceutical formulations.

Interconnected Nickel Nanowires – the Missing Link between Metallic High Surface Area Catalysts and High Porosity Foams

Porous and electrically conductive materials having extended surface area are attractive for wide range of applications, such as catalysis, sensing or energy storage. High surface area of the material provides higher reaction rates and lower electrode resistance. For instance, metallic sponges such as Raney nickel, having surface areas up to 100 m2/g show high catalytic activity during water electrolysis or heterogenous organic synthesis. However, low porosity and small average pore diameter limit their application for devices utilizing additional functional layers (e.g. active electrode materials in batteries). On the other hand, highly porous nickel foams are commonly used as current collectors for Ni- and Zn-based batteries, where sufficient loading of active material can be realized inside of the porous network. However, the surface area of such foams is more than three orders of magnitude smaller than that of the metallic sponges, lowering the potential for e.g. high rate operations of their parent devices. In this talk we will present a recently developed material composed of interconnected nickel nanowires of controllable diameter and distance. The nanowires assembly offers a unique combination of high surface area of metallic sponges and high porosity of metallic foams. The material is conveniently obtained by cheap and up-scalable electrochemical techniques. The unique nanostructural properties of the interconnected nanowires allow for high flexibility of the material and applications in e.g. flexible electronics or wearable sensors. As a proof-of-concept, we will present the performance of our structure for hydrogen generation during water electrolysis. Compared to nickel foams, the high surface area interconnected nanowires offers significantly higher hydrogen evolution currents, showing their potential for next generation electrolyzers and energy devices. Figure 1

Copper Electrode Fabricated via Pulse Electrodeposition: Toward High Methane Selectivity and Activity for CO2 Electroreduction

Electrochemical reduction of CO2 (ERC) to methane has significant economic benefits and represents one promising solution for energy and environmental sustainability. However, traditional metal electrodes suffer from higher overpotentials, low activities, and poor selectivity. In this article, the pulse electrodeposition (P-ED) method is employed to prepare a copper electrode for ERC. The P-ED method can easily create Cu coatings on carbon paper with a much rougher surface and extended surface area, which is highly beneficial for improving their activity and selectivity. As a result, the prepared Cu electrodes exhibit high faradaic efficiency (of 85% at −2.8 V) and enhanced partial current density (jCH4 = 38 mA cm–2) for methane, which is by far the highest value ever reported at room temperature and ambient pressure. The enhanced activity is attributed to the extended reactive areas with rough morphology and loosened coating structure to ensure CO2 access the reaction sites located at the sublayers of th...

Potential Applications of Nanocellulose-Containing Materials in the Biomedical Field.

Because of its high biocompatibility, bio-degradability, low-cost and easy availability, cellulose finds application in disparate areas of research. Here we focus our attention on the most recent and attractive potential applications of cellulose in the biomedical field. We first describe the chemical/structural composition of cellulose fibers, the cellulose sources/features and cellulose chemical modifications employed to improve its properties. We then move to the description of cellulose potential applications in biomedicine. In this field, cellulose is most considered in recent research in the form of nano-sized particle, i.e., nanofiber cellulose (NFC) or cellulose nanocrystal (CNC). NFC is obtained from cellulose via chemical and mechanical methods. CNC can be obtained from macroscopic or microscopic forms of cellulose following strong acid hydrolysis. NFC and CNC are used for several reasons including the mechanical properties, the extended surface area and the low toxicity. Here we present some potential applications of nano-sized cellulose in the fields of wound healing, bone-cartilage regeneration, dental application and different human diseases including cancer. To witness the close proximity of nano-sized cellulose to the practical biomedical use, examples of recent clinical trials are also reported. Altogether, the described examples strongly support the enormous application potential of nano-sized cellulose in the biomedical field.

Characterisation of platinum electrodeposits on a titanium micromesh stack in a rectangular channel flow cell

Platinised titanium mesh is a common electrode material in industrial electrolytic cells and Ce-based redox flow batteries. In this work, the electrodeposition of platinum on a stack of titanium micromeshes is performed from a flowing alkaline solution in a rectangular channel, divided flow cell. The morphology and distribution of the resulting platinum deposits are studied by SEM, EDS mapping and X-ray computed tomography. The active surface area of the electrode was assessed from the charge transfer current for the reduction of Ce(IV) ions and compared to that of planar and expanded metal mesh electrodes. The surface area was estimated by hydrogen electrosorption relative to that at a planar Pt/Ti electrode. As expected from the potential drop within the electrode channel, the individual micromesh near the cell separator showed a higher platinum content. Pt/Ti micromesh offers an extended surface area and enhanced mass transport compared to planar electrodes and conventional expanded metal mesh anodes. The applications for these and alternative electrode structures are discussed.

Supramolecular Nanofibers as Ambient Stable Wide Voltage Window Electrolyte for Micro‐Supercapacitors

AbstractIn this paper, we explore the use of supramolecular nanofibers as an electrolyte for in‐plane micro‐supercapacitors. The supramolecular nanofibers obtained from the self‐assembly of donor–acceptor (D‐A) molecules, coronene tetracarboxylate salt (CS) and dodecyl methyl viologen (DMV), carrying positive and negative ionic charges, respectively, were drop‐coated onto metal gap electrodes using an aqueous dispersion to form the device. Under dry conditions (<35 % relative humidity, RH), the device exhibited a stack capacitance of 160 F cm−3 with energy and power densities comparable to high‐performance micro‐supercapacitors. Although the electrolyte has aqueous origin, in dry conditions, it is capable of operating in a voltage window of 0–3 V. This supramolecular micro‐supercapacitor device (micro‐SS) was fabricated only with metal electrodes without using electrode material in it, thanks to the ability of the nanofiber to provide extended surface area for charge storage. The 1D face‐to‐face arrangement of D‐A molecules seems to provide an efficient pathway for the diffusion of ions across the electrodes. The present study not only provides a new approach to obtain an ambient stable electrolyte with wide operating voltage window but also gives a low‐cost method of fabricating micro‐supercapacitors with reasonably high energy and power densities.

Porous Gold Nanowires: Plasmonic Response and Surface‐Enhanced Infrared Absorption

Because of its extended surface area porous gold is of potential interest for surface‐enhanced spectroscopy methods. Optical properties of porous and smooth gold nanowires of similar diameter are analyzed with infrared spectroscopy and modeled with finite‐difference time‐domain simulations. By electrochemical deposition in ion‐track etched polymer smooth gold and gold–silver alloy nanowires are synthesized. Porous gold nanowires are subsequently obtained by dealloying. The porosity clearly affects important plasmonic characteristics, resulting in a strong redshift of the resonant wavelength, and significant line broadening, which can be convincingly explained by effective Drude parameters related to a lowered average electron density and a higher electron scattering in the porous gold, respectively. Finally, the sensing performance of porous wires is tested by surface‐enhanced infrared absorption. The measurements show a similar vibrational signal contrast for smooth and porous wires. This is explained by simulations which reveal that the nanowire near‐field modeled with bulk gold data is higher and thus accordingly the vibrational signal is enhanced compared to nanowires modeled with the effective Drude parameters of porous gold. This means that the advantages offered by the larger surface of porous wires are counterbalanced by lower near‐field strength.

Graphene/poly(3,4-ethylenedioxythiophene)/Fe3O4 nanocomposite – An efficient oxygen reduction catalyst for the continuous electricity production from wastewater treatment microbial fuel cells

The ternary composite comprising reduced graphene oxide (rGO), poly(3,4-ethylenedioxythiophene) (PEDOT) and iron oxide (Fe3O4) nanorods is developed and its substantial contribution toward the green energy generation of air cathode microbial fuel cells (ACMFC) as an efficient oxygen reduction reaction (ORR) catalyst is evaluated by using the different electrochemical techniques under various regimes and conditions. The effectual distribution of needle like and cubic inverse spinel structured Fe3O4 nanorods over the PEDOT enveloped graphene sheets are elucidated from the electron micrographs and the growth and composite formation mechanisms of Fe3O4 and rGO/PEDOT/Fe3O4, respectively, are enunciated from the detailed structural characterizations. The extended surface area, high electrical conductivity, and large oxygen adsorption sites of rGO/PEDOT/Fe3O4 nanocomposite facilitate the excellent ORR kinetics, which yields the maximum ACMFC power density with the superior durability of more than 600 h. Thus the proposed strategy extends a new approach in bringing the advantages of active carbon, conductive polymer and nanomaterials in a single tool, which constructs the prepared ternary composite as a potential ORR contender to the commercially available catalysts.

In vitro Evaluation of Antibacterial Efficacy using Passiflora foetida Activated Carbon

<p><strong>Activated carbon (AC) has found its attention in pollution control and wastewater treatment to remove various pollutants. Activated carbon can be prepared by physical and chemical activation methods. The chemical activation methods were advantageous over physical activation due to process accomplishment at lower temperature and greater yield which avoids burn-off char. Activated carbon was usually used as an adsorbent for dye removal from wastewater which could be related to their extended surface area, high adsorption capacity, microporous structure and special surface reactivity. Microbial pollution and contamination have produced various problems in industrial and medical fields. Based on this, the present study was attempted on the preparation of activated carbon from <em>Passiflora foetida</em> and evaluating for its antibacterial efficacy against twelve different microorganisms by agar well diffusion method. The results were found to be very effective with higher zone of inhibition against almost all the microorganisms tested. Moreover, the activity was considerably more against <em>Shigella flexneri (MTCC 1457) </em>and <em>Klebsiella pneumoniae (MTCC 10309).</em>In addition to this, the shake flask test in saline had proved that the colonial growth of <em>E.coli</em> was inhibited with respect to the concentration of activated carbon and time of incubation.</strong></p><p><strong> </strong></p>

Identification of Cu surface active sites for a complete nitrate-to-nitrite conversion with nanostructured catalysts

Nitrate reduction on Pt nanostructured films, PtNSF, with an extended surface area (roughness factor of ca. 30), and close to 50% of (100) surface sites modified by Cu adatoms through underpotential deposition (Cuupd/PtNSF), has been studied by means of linear sweep voltammetry (LSV), electrolysis at constant potential, and chemical analysis of the formed products. According to the LSV curves, the adsorption and reduction of nitrates occur preferentially at Cu(100) surface sites and at a potential positive (+0.15V) of the hydrogen reversible potential. In these conditions, the nitrate-to-nitrite conversion is achieved on the Cu(100) sites, with a faradic efficiency in excess of 95%, and a conversion selectivity of 98%.

English

The industry revolution in thermal engineering started with fixed the extended surface area named a fin. Therefore, a lot off research work done in this field to enhance the performance of heat transfer. All, previous work reach to that any increase of heat transfer coefficient and the fin surface area will increase the heat transfer rate by natural convection. The research work summarized in this paper presents an experimental investigation on the effect of fin heights –width (H/w) ratios on the fin performance using rectangular plate type fins. The steady-state natural convection heat transfer from vertical rectangular fins extending perpendicularly from horizontal square aluminum base was investigated experimentally at high range of temperatures from 60 to 110°C. Four fin heights 30mm,40mm,50mm,60mm were employed under free convection heat transfer conditions. The heat transfer area was kept the same. The performance of the fin expressed in terms of fin efficiency, overall fin efficiency, fin effectiveness and thermal resistance as a function of fin height parameters has been study at fin height and width (H\w) ratios 0.2,0.35,0.55 and 0.8 respectively in this work. The dimensionless parameter Biot no. for different fin height-width (H\w) ratios to the fin heat transfer rate. Results show that's fin heat transfer performance increase with decreasing the fin heights and increasing the fin width for the range of temperatures used.

Electro-chemical preparation and characterization of poly(1-amino-9,10-anthraquinone) films in a micelle solution of sodium dodecyl sulfate

In this work, the poly(1-amino-9,10-anthraquinone) (PAAQ) films are synthesized electro-chemically by the direct anodic oxidation of 1-amino-9,10-anthraquinone (AAQ) on a platinum substrate in an ionic micelle solution containing the environmental friendly surfactant sodium dodecyl sulfate (SDS). The PAAQ–SDS films prepared are characterized by cyclic voltammetry (CV) and scanning electron microscopy (SEM), and a comparative study is carried out on the PAAQ films prepared under the identical conditions but in the absence of SDS. The results obtained show that the AAQ polymerization rate increases initially with an increase in the concentration of SDS, passed through a maximum around 0.4mM, and then decreased towards lower values, with a further increase in the SDS concentration. The PAAQ films deposited onto the electrode surface using the CV technique were adhesive and homogeneous. A distribution of the small particles and an extended surface area were observed in the SEM images for the porous PAAQ–SDS films. The preliminary results obtained show that the reliability and stability of the PAAQ–SDS modified electrode provide a good possibility for the electro-analytical determination of catechol.

Pes Anserinus Structural Framework and Constituting Tendons Are Grossly Aberrant in Nigerian Population.

We evaluated the morphological framework of the pes anserinus in both knees of ten Nigerian cadavers and we observed high degree of variability in its morphology and location. The pes anserinus inserted specifically on the superior half of the media border of the tibia, as far inferiorly as 124.44 mm to the tibial tuberosity (prolonged insertion). The insertion was also joined to the part of tibia close to the tibia tuberosity (90%) and to the fascia cruris (10%). The initial insertion point of the pes anserinus was always found at the level of the tibia tuberosity. We found out that accessory bands of sartorius, gracilis, or semitendinosus were part of the pes anserinus in 95% of all occasions studied whereas the combined occurrence of monotendinosus sartorius, gracilis, and semitendinosus tendons was found in only 5% of all occasions. The pes anserinus did not conform to the layered pattern and the tendons of sartorius, gracilis, or semitendinosus were short. The inferior prolongation of the pes anserinus connotes extended surface area of attachment to support the mechanical pull from the hamstring muscles. This information will be useful in precise location and grafting of the pes anserinus.

Additive electrospraying: a route to process electrospun scaffolds for controlled molecular release

Electrohydrodynamics—i.e. electrospinning, electrospraying and atomization—are gaining a growing interest in drug delivery applications, because of a large number of advantages including improved therapeutic index, localized delivery/targeting and controlled drugs toxicity level. In the past, microstructured platforms fabricated by the assembly of electrospun fibers have demonstrated to exhibit interesting features as bioactive carriers including extended surface area and high molecular permeability because of fully interconnected pore architecture, thus making the opportunity to incorporate a wide range of actives/drugs for different use. In these systems, molecular release occurs via various molecular transport pathways namely diffusion, desorption and scaffold degradation which may be tuned through a careful control of fiber morphology and composition. However, several shortcomings still concern the possibility to incorporate bioactive species, not exposing molecules to fast and/or uncontrolled denaturation, thus preserving biochemical and biological fiber functionalities. In this context, additive electro spraying (AES)—i.e. integration of electrosprayed nanoparticles into electrospun fiber network—is emerging as interesting route to control “separately” release and functional properties of the scaffolds in order to support cell activities by independent cues, during the tissue formation. Here, we describe the current advances on the use of electrospraying and/or electrospinning until more innovative integrated AES approaches to design molecularly loaded platforms able to spatially and timely release active molecules for different use in tissue engineering and molecular targeting. Copyright © 2015 John Wiley & Sons, Ltd.

Characterisation of Nanoporous Gold for Use in a Dissolved Oxygen Sensing Application

A nanoporous gold (NPG) microdisc array in a three-electrode electrochemical cell arrangement has been fabricated and characterised for a dissolved oxygen sensing application. The device will be used for monitoring of drinking water quality in rural communities in India, where there is a need for a miniaturised, low-cost dissolved oxygen sensor. The NPG microdisc array exhibits improved electrochemical responses compared to a planar gold microdisc array, owing to its extended surface area. In 1 mM ferrocene carboxylic acid, the experimental limiting currents obtained are twice as large as the theoretical limiting current for a planar gold microarray. A 252-nm-thick NPG layer resulted in a limiting current of 627 nA (compared to the estimated current of 295 nA). The voltammetric behaviour in water samples from a pilot site in India was investigated for increasing oxygen content, and a comparison was made with a macrodisc gold electrode and an unmodified microdisc array. The NPG microdisc array demonstrated improved characteristics over both devices and exhibited a higher correlation (average value 0.925) compared with the unmodified array (0.819) and macrodisc (0.870). An improvement in signal-to-noise ratio was also observed to be 12.349 versus 5.259 (microelecrode array) and 5.604 (macroelectrode). The response time for the NPG microdisc array versus a commercial dissolved oxygen sensor showed a faster response time of 20 versus 40 s.

Hydraulic Conductivity Estimation Test Impact on Long-Term Acceptance Rate and Soil Absorption System Design

The aim of this paper was to verify the common methods of hydraulic conductivity estimation for soil assessment in respect to wastewater disposal. The studies were conducted on three types of sandy soils. Hydraulic conductivity was determined using a scale effect-free laboratory method, empirical equations and compared with measurements estimated from a laboratory infiltration column with identified head loss. Based on the hydraulic conductivity values, the long-term acceptance rates (LTAR) [1] were calculated. The differences in LTAR values were about one order of magnitude smaller than differences in hydraulic coefficient. The study showed a good convergention of the results obtained from the constant head method (CHM) by solving the Glover Equation for medium and coarse sands. In low permeability soil (fine sand), the best result was obtained using CHM-a with a capillary rise consideration (a is a factor included in the flow in the unsaturated and saturated zones calculated from a capillary rise). From a practical point of view the relatively small value of LTAR underestimation (20%-for constant head method) is responsible for the extended surface area of the system and provides a security margin (the avoidance of clogging risk). The use of the falling head method, based on the Van Hoorn equation, can be said to be highly overestimated. For medium and coarse sandy soils the underestimation of LTAR calculated and based on CHM test determination is 14%–18%. The total cost of soil absorption system (SAS) designed-based on CHM in comparison to that designed-based on real hydraulic conductivity value in Poland is only about 7%–9% higher.

One-pot synthesis of CdS–reduced graphene oxide 3D composites with enhanced photocatalytic properties

Nest-like CdS–reduced graphene oxide (CdS–rGO) composites were prepared through a one-pot solvothermal method in which ethylenediamine was used to reduce GO and control the morphology of the CdS, and L-cysteine was used as the sulfur source, reducing agent, and linker between the CdS and rGO. By examining the morphology, structure, and composition of the composites, it could be found that the nest-like CdS particles were decorated on the rGO sheet, and the addition of GO did not influence the crystal structure and shape of the nest-like CdS. Compared with pure CdS, the as-prepared CdS–rGO composites showed enhanced visible light absorption, extended surface area, and facilitated separation of photogenerated charges. Hence, the CdS–rGO composites exhibited improved photocatalytic activity and excellent photostability for the degradation of rhodamine B under visible light irradiation. By combining the good properties of rGO and three-dimensional structured CdS microparticles, the strategy presented in this study is expected to be useful in preparing highly efficient graphene–semiconductor composites for potential applications in various fields.

Surface treatments of silver rods with enhanced iodide adsorption for I-125 brachytherapy seeds

This study described an effective method to load 125I on silver rods for the preparation of a brachytherapy source. We tested various ligands on the silver rod surface to screen the one with the highest adsorption and specific radioactivity. In addition, we investigated the effect of surface etching to increase the adsorption capability followed by the extended surface area. We also found that the use of an oxidant during iodide adsorption can increase the loading significantly. The maximum activity of 137.90MBq/rod (3.7269mCi/rod) was achieved on the etched silver rods with phosphate ligand and hydrogen peroxide as an oxidant. In addition, this is 4.5-fold higher than that of the conventional chloride treatment method.

Template-derived high surface area λ-MnO2 for supercapacitor applications

The synthesis of lambda-manganese oxide (λ-MnO2) with a developed porosity and an ordered and interconnected pore structure used as supercapacitor electrode is reported for the first time in the present study. A spinel-type LiMn2O4 material was first prepared by hard-templating pathway using KIT-6 mesoporous silica as a template and metal nitrates as precursors, which was subsequently acid treated leading to λ-MnO2 material. The materials exhibit high surface area (up to 150 m2 g−1), defined pore size distribution with three-dimensional interconnected pores, and crystalline pore walls. The material textural properties as well as the morphologies vary considerably with the synthetic conditions. The as-synthesized porous λ-MnO2 materials exhibit a noticeably better performance (120 F g−1) at high constant currents (1 A g−1) than commercial derived λ-MnO2 (11 F g−1). The extended surface area and the porous and three-dimensional interconnected structures along with the specific morphology significantly enhance the lithium diffusion through the particles and allow for a more effective use of this pseudocapacitive material as an electrode in supercapacitor.