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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 91 records · Page 5
All sourcesNASA NTRSDOE OSTI
DOE OSTI2016

Nickel/silicon core/shell nanosheet arrays as electrode materials for lithium ion batteries

Highlights: • Ni nanosheet arrays is the core and Si layer is the shell. • Ni nanosheet arrays act as a three-dimensional current collector to support Si. • Ni nanosheet arrays can improve the conductivity and stability of the electrode. • Ni/Si nanosheet arrays exhibit excellent cyclic and rate performance. - Abstract: Ni/Si core/shell nanosheet arrays are proposed to enhance the electrochemical lithium-storage properties of silicon. The arrays are characterized by means of X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The arrays are micro-sized in height, which are constructed by interconnected Ni nanosheet as the core and Si coating layer as the shell. The electrochemical properties as anode materials of lithium ion batteries are investigated by cyclic voltammetry (CV) and galvanostatic charge-discharge tests. The arrays can achieve high reversible capacity, good cycle stability and high rate capability. It is believed that the enhanced electrochemical performance is attributed to the electrode structure, because the interconnected Ni nanosheet can act as a three-dimensional current collector, and it has the ability of improving the electrode conductivity, enlarging the electrochemical reaction interface, and suppressing the electrode pulverization.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Investigation of super-capacitive nature of reduced graphene oxide nano mesh grown over 18 k gold foil using wings of Parides iphidamas as biological template

Highlights: • Novel rGO nano mesh (rGONM) like assembly was fabricated using bio-template method. • rGONM pattern exhibit nano-ridges (40 nm) and ribs (25 nm) resembling fishing net. • Super-capacitor performances of rGO and rGONM coated Au substrates were evaluated. • rGO-Au and rGONM-Au revealed specific capacitances of 291 and 418 F/g respectively. - Abstract: This paper deals with the fabrication of novel, reduced graphene oxide nano mesh (rGONM) patterns with longitudinal nano-ridges and transverse nano-ribs using nano tubular structures found on the scales of Parides iphidamas, a butterfly species as biological template. Raman spectra, EDAX and FTIR results confirm the obtained mesh-like morphology that comprises only reduced graphene oxide (rGO). Further, super-capacitor performances of rGO and rGONM-coated gold substrates have been evaluated using cyclic-voltammetry (CV), galvanostatic charge-discharge cycle (GCD) and electrochemical impedance spectroscopic (EIS) analysis. A characteristic rectangular curve obtained from the CV of rGO and rGONM-coated gold electrodes display specific capacitances of 291 F/g and 418 F/g respectively at a scan rate of 5 mV/s. The results obtained from EIS support the superior nature of rGONM-coated electrode against rGO system, suggesting the use of rGONM-Au as a potential candidate for electrochemical super capacitor applications.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2018

Ultrasensitive and selective non-enzymatic electrochemical glucose sensor based on hybrid material of graphene nanosheets/graphene nanoribbons/nickel nanoparticle

Highlights: • Nickel nanoparticles incorporated graphene nanosheets/graphene nanoribbons (GS/GNR/Ni) composite was synthesized by in-situ chemical reduction route and the as prepared GS/GNR/Ni modified glassy carbon electrode (GCE) was applied to detect glucose. • The fabricated GS/GNR/Ni/GCE modified electrode exhibits outstanding performance for non-enzymatic glucose sensing with sensitivity (2.3 mA/mM cm{sup 2}), linear range (5 nM - 5 mM) and detection limit (2.5 nM). • GS/GNR/Ni/GCE modified electrode exhibited a high selectivity towards glucose against the interferents, such as ascorbic acid (AA), uric acid (UA), dopamine and sucrose. - Abstract: A fast, highly sensitive and selective non-enzymatic electrochemical glucose sensor based on graphene sheet/graphene nanoribbon/nickel nanoparticles (GS/GNR/Ni) hybrid material modified electrode was fabricated. The hybrid material was synthesized via facile in-situ chemical reduction and characterized by X-ray diffraction, transmission electron microscopy, Raman spectroscopy, cyclic voltammetry and electrochemical impedance spectroscopy. The GS/GNR/Ni/GCE showed high electrochemical activity towards the oxidation of glucose in a 0.1 M NaOH solution. At an applied potential of +0.5 V, it displayed wide linear amperometric response towards glucose from the range of 5 nM–5 mM, with a detection limit of 2.5 nM and sensitivity of 2.3 mA/mM cm{sup 2}. Moreover, the modified electrode was relatively insensitive to commonly interfering species such as dopamine, ascorbic acid, sucrose, uric acid and Cl{sup −} ions. The fabricated sensor with better reproducibility, good long term stability, makes it a promising electrode for the development of effective glucose sensor.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2018

Improvement on the catalytic activity of the flexible PEDOT counter electrode in dye-sensitized solar cells

Highlights: • The catalytic activity of PEDOT electrode can be tuned by varying deposited time. • A highly effective Pt/PEDOT electrode was also prepared. • The DSSCs using Pt/PEDOT counter electrode shows high efficiency of 7.90%. - Abstract: A flexible Poly (3, 4-ethylenedioxythiophene) (PEDOT) electrode on indium-doped tin oxide coated polyethylene naphthalate (ITO-PEN) substrate is prepared by electrochemical methods for dye-sensitized solar cells (DSSCs) as counter electrode. The impact of deposition time on the catalytic activities of the flexible PEDOT electrode towards the iodide redox couple has been investigated by cyclic voltammetry, electrochemical impedance spectroscopy (EIS) and Tafel polarization curve measurements. After optimization, the DSSCs using PEDOT counter electrode deposited 80 s shows power conversion efficiency (PCE) of 7.18%, close to than the Pt counter electrode based counterpart (7.56%). To further improve the catalytic activity of PEDOT, Pt/PDEOT composite catalyst is synthesized. And the DSSCs with the Pt/PDEOT composite CE generates a high PCE of 7.90%.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Synthesis and electrochemical properties of silver dendrites and silver dendrites/rGO composite for applications in paracetamol sensing

Highlights: • Synthesis of Ag dendrites and GO/Ag dendrites composites by Galvanic Replacement method. • Ag dendrites are wrapped over graphene sheets. • High sensitivity (10.046 μA cm{sup −2} mM{sup -1)} and lower limit of detection of 0.025 μM for sensing of Paracetamol. - Abstract: Electrochemical sensors are one of the important applications of electrochemistry. In this paper, synthesis, characterization and application of Silver Dendrites and Silver Dendrites/rGO sensors for simple and fast determination of Paracetamol are described. Silver dendrites and their composite with graphene oxide were synthesized by galvanic replacement method. The synthesized samples were characterized by XRD, SEM and TEM. XRD reveals the FCC structure of silver and TEM images show the formation of dendritic silver wrapped in the graphene sheets. The Electrochemical paracetamol sensing properties of these samples were tested using cyclic voltammetry and chronoamperometry. The silver dendrites exhibit a sensitivity of 2.807 × 10{sup 5}μA/mM/g and a lower detection limit of 2.5 μM, whereas, the composite with graphene oxide exhibits a high sensitivity of 2.511 × 10{sup 6}μA /mM/g with a lower detection limit of 0.025 μM.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Facile synthesis and photocatalytic activity of Ag3PO4 decorated MoS2 nanoflakes on carbon fiber cloth

Highlights: • A novel CC@MoS{sub 2}-Ag{sub 3}PO{sub 4} heterostructure is fabricated by a facile method. • The growth process of CC@MoS{sub 2} is investigated. • The heterostructure displays an excellent photocatalytic property. • Cyclic Voltammetry is utilized to investigate the photocatalytic mechanism. - Abstract: A novel CC@MoS{sub 2}-Ag{sub 3}PO{sub 4} heterostructure, composed of Ag{sub 3}PO{sub 4} nanoparticles decorated MoS{sub 2} nanosheets on carbon fiber cloth (CC), is fabricated by a simple hydrothermal method and a successive ionic layer absorption reaction. The CC@MoS{sub 2}-Ag{sub 3}PO{sub 4} heterostructure displays an excellent photocatalytic activity of ∼96% degradation rate for RhB solution under simulated daylight, which is more than 10 times as much as that of pure Ag{sub 3}PO{sub 4} or MoS{sub 2}. The CC@MoS{sub 2}-Ag{sub 3}PO{sub 4} heterostructure with optimized photoactivity is investigated by optical and electrochemical measurements. The CC@MoS{sub 2}-Ag{sub 3}PO{sub 4} heterostructure can not only broaden the photoresponse range of MoS{sub 2}, but also alleviate the photodegradation of Ag{sub 3}PO{sub 4}, and the easily separated CC provides a proper conductive substrate and rapid charge transfer channels. The probable photocatalytic mechanism of CC@MoS{sub 2}-Ag{sub 3}PO{sub 4} heterostructure is discussed in detail. Therefore, the CC@MoS{sub 2}-Ag{sub 3}PO{sub 4} heterostructure with high efficient photocatalytic performance and easy separation is a promising photocatalytic material.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Reversible Mg insertion into chevrel phase Mo6S8 cathode: Preparation, electrochemistry and X-ray photoelectron spectroscopy study

Highlights: • Surface modification of Mo6S8 to enhance the reactivity against Mg. • Mechanism study using XPS and EIS. • Excellent Mg-ion battery performance. - Abstract: Electrical energy storage is absolute for complete usage of all renewable energy sources. Herein, we have studied the electrochemical performance of Chevrel phase Mo{sub 6}S{sub 8} as cathode material towards rechargeable Mg battery. Solution chemistry route is adopted for the synthesis of Mo{sub 6}S{sub 8.} The morphology, phase purity is analyzed by Scanning Electron Microscopy, Transmission Electron Microscopy, and X-Ray Diffraction techniques. The cyclic Voltammetry and Galvanostatic charge-discharge studies confirmed the reversibility of Mg-ion insertion. Herein, Mo{sub 6}S{sub 8} cubes show excellent capacity retention of 70 mAh g{sup −1} for 200 cycles at C/5 rate. The role of CNT in improving rate performance was also demonstrated. The reasonable reversible capacity, rate performance, and cycling stability reveal the feasibility of Mo{sub 6}S{sub 8} material for future rechargeable Mg battery. In order to study the kinetics of Chevrel phase compound upon cycling, EIS study was carried out. The redox process upon insertion/extraction is investigated by X-ray Photoelectron spectroscopy which shows no change in oxidation state of a transition metal.

25 ENERGY STORAGE↗
DOE OSTI2018

The band structure and photocatalytic mechanism of MoS2-modified C3N4 photocatalysts with improved visible photocatalytic activity

Highlights: • A series of MoS{sub 2}/g-C{sub 3}N{sub 4} photocatalyst were prepared by water exfoliation method. • The heterojunction enhanced the visible response and separated charge carriers. • The MoS{sub 2}/g-C{sub 3}N{sub 4} exhibits enhanced visible photocatalytic activity. - Abstract: A series of MoS{sub 2}/g-C{sub 3}N{sub 4} photocatalysts were prepared by modifying g-C{sub 3}N{sub 4} with different concentration of MoS{sub 2} via a water exfoliation method. The crystal structure, morphology, band structure of heterojunction, behaviors of charge carries and the redox ability were characterized by XRD, HR-TEM, absorption spectra, XPS, PL, cyclic voltammetry curves and transient photocurrent spectra. It is revealed that the introduction of MoS{sub 2} on the surface of g-C{sub 3}N{sub 4} nanosheets to form micro-heterojunction could enhance the visible response and separate photogenerated charge carriers effectively. Moreover, the ability of the photocatalyst for generating reactive oxygen species (ROS, such as O{sub 2}{sup −} and OH) was also investigated. Therefore, MoS{sub 2}/g-C{sub 3}N{sub 4} samples exhibit better photocatalytic performance for the photodegradation of HCHO than g-C{sub 3}N{sub 4} and MoS{sub 2} under visible irradiation.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2018

Synthesis and physical properties of NaxTO2 (T = Mn, Co) nanostructures for cathode materials in Na-ion batteries

Highlights: • Synthesis of stable Na{sub x}TO{sub 2} (T = Mn, Co) nanostructures using a sol–gel method. • Absence of any long-range magnetic ordering in both compounds till 5 K. • Activated type conduction at high temperatures and VRH at low temperatures in Na{sub x}CoO{sub 2}. • Disorder assisted VRH conduction takes place in Na{sub x}MnO{sub 2} near room temperature. • Cyclic voltammetry confirm reversibility of Na ion in a coin cell using Na{sub x}TO{sub 2} cathode. - Abstract: We prepared Na{sub x}TO{sub 2} (T = Mn, Co) nanostructures to use as cathode material in Na-ion batteries. The Rietveld refinement of X-ray diffraction data confirms the hexagonal symmetry. Scanning and transmission electron microscopy measurements show hexagonal and rod-shape morphology for T = Co and Mn, respectively. The magnetic measurements indicate the presence of variable oxidation states of Mn/Co ions, but no long range ordering till 5 K. We find that the Na{sub 0.6}MnO{sub 2} is highly insulating whereas Na{sub 0.7}CoO{sub 2} is semiconducting in nature. The conduction in Na{sub 0.7}CoO{sub 2} takes place through both variable range hopping (VRH) as well as activation mechanisms in different temperature ranges. However, for Na{sub 0.6}MnO{sub 2} the VRH prevails at elevated temperatures. Furthermore, the coin cells have been fabricated and tested the electrochemical behavior using cyclic voltammetry, which confirms the reversibility of Na-ions during intercalation/de-intercalation.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2018

Nanoparticles-constructed spinel ZnFe2O4 anode material with superior lithium storage performance boosted by pseudocapacitance

Highlights: • Nanoparticles-constructed ZnFe{sub 2}O{sub 4} was fabricated by co-precipitation method. • The ZnFe{sub 2}O{sub 4} sample shows excellent high rate capability and cycling stability. • The lithium storage mechanism was analyzed by CV and EIS measurements. • Pseudocapacitive effect has a significant contribution to the total stored charge. - Abstract: The practical application of ZnFe{sub 2}O{sub 4} in lithium ion batteries (LIBs) is severely hampered by its fast capacity fading and poor rate performance. To overcome these issues, herein, ZnFe{sub 2}O{sub 4} powders consist of aggregated nanoparticles (50∼100 nm) with porosity were prepared by a facile co-precipitation method and subsequent thermal decomposition. When used as anode material for LIBs, the ZnFe{sub 2}O{sub 4} sample delivers capacities of 920, 820, 650, 485, and 421 mA h g{sup −1} at current densities of 0.5, 1, 3, 7, and 10 A g{sup −1}, respectively. Moreover, the sample can maintain a capacity of 814 mA h g{sup −1} even after 300 cycles at the current density of 1 A g{sup −1}, implying an excellent rate capability and cycling stability. Cyclic voltammetry analysis reveals that both diffusion-controlled lithium storage and surface pseudocapacitive lithium storage contribute to the total stored charge of ZnFe{sub 2}O{sub 4}, which boosts the high rate capability and superior cycling stability of the ZnFe{sub 2}O{sub 4}.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2018

Rational fabrication of carbon nanotubes arrays on porous nickel matrix as advanced electrode materials of supercapacitors

Highlights: • Construct self-supported porous Ni/CNTs composite arrays. • Porous Ni/CNTs arrays show superior capacitive performance. • Ni/CNTs arrays structure boosts fast electron/ion transfer. - Abstract: Rational synthesis of advanced carbon materials is of great importance to the development of supercapacitors. In this work, we propose a facile combined electrodeposition-chemical vapor deposition for tailored construction of carbon nanotubes (CNTs) arrays on highly porous Ni matrix forming integrated 3D Ni/CNTs electrode. Interconnected CNTs with diameters of 20–30 nm are strongly anchored on the cross-linked porous Ni branches consisting of nanoparticles of 500–600 nm. Capacitive performance of the obtained porous Ni/CNTs electrode is thoroughly characterized by electrochemical means including charge/discharge tests and cyclic voltammetry. The 3D Ni/CNTs electrode shows good high-rate performance with a capacitance of 186 F g{sup −1} at 2.5 A g{sup −1}, and excellent cycling stability with a capacitance retention of 99% after 10,000 cycles. The integrated conductive network composed of 3D Ni/CNTs offers large active area, good electronic conductivity and fast transportation paths of ions/electrons, leading to superior capacitive performance.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2018

Flexible and freestanding catalase-Fe3O4/reduced graphene oxide paper: Enzymatic hydrogen peroxide sensor applications

Highlights: • The preparation of a new type of flexible Cat-Fe{sub 3}O{sub 4}/rGO paper was achieved by a simple method. • The characterization of the Fe{sub 3}O{sub 4} nanocrystals formed on rGO and Cat-Fe{sub 3}O{sub 4}/rGO paper were investigated by several techniques. • Cat-Fe{sub 3}O{sub 4}/rGO paper electrode was used as a flexible electrochemical sensor for H{sub 2}O{sub 2} determination. - Abstract: We proposed a new type of freestanding Catalase (EC 1.11.1.6) (Cat) modified paper electrode based on Fe{sub 3}O{sub 4} crystals decorated freestanding reduced graphene oxide (rGO) paper (Cat-Fe{sub 3}O{sub 4}/rGO) using a facile electrodeposition method. This enzyme modified paper electrode was used for the specific determination of hydrogen peroxide (H{sub 2}O{sub 2}). Structural, chemical, and morphological characterization of the Fe{sub 3}O{sub 4} crystals formed on rGO paper was investigated by (i) using scanning electron microscopy (SEM), (ii) energy-dispersive X-ray spectroscopy (EDS), (iii) X-ray photoelectron spectroscopy (XPS), (iv) X-ray diffraction spectroscopy (XRD), (v) Raman spectroscopy, (vi) electrochemical impedance spectroscopy (EIS) and (vii) cyclic voltammetry (CV) techniques. The Cat enzyme was successfully adsorbed on the Fe{sub 3}O{sub 4} nanocrystals surface which was demonstrated by fluorescence microscopy. The Cat-Fe{sub 3}O{sub 4}/rGO paper electrode showed excellent electrocatalytic activity toward H{sub 2}O{sub 2}. It is found that Cat-Fe{sub 3}O{sub 4}/rGO paper electrode shows a wide linear range, high sensitivity, and a low detection limit for H{sub 2}O{sub 2} detection.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Ruthenium oxide nanostring clusters anchored Graphene oxide nanocomposites for high-performance supercapacitors application

Highlights: • GO-RuO{sub 2} nanocomposites were synthesized by simple hydrothermal method. • GO-RuO{sub 2} nanocomposites were characterized by XRD, SEM, TEM and EDS. • GO-RuO{sub 2} nanostring composite has shown a maximum specific capacitance of 859 Fg{sup −1} at the scan rate of 5 mVs{sup −1}. • GO-RuO{sub 2} nanostring composite electrode exhibits tremendous cyclic stability. - Abstract: Here, we report simple hydrothermal method for the preparation of Graphene oxide (GO) is embellished with nanostring clusters of ruthenium oxide (GO-RuO{sub 2}). The structure of the nanocomposite material was ascertained using X-ray diffraction (XRD), Raman spectroscopy, Scanning electron spectroscopy (SEM), Energy dispersive spectroscopy (EDS) and Transmission spectroscopy (TEM). The supercapacitor performance of the nanocomposites was investigated in acidic electrolyte, 1.0 M H{sub 2}SO{sub 4}, in a three-electrode setup. GO-RuO{sub 2} nanostring composite has shown a maximum specific capacitance of 859 Fg{sup −1} at the scan rate of 5 mVs{sup −1} using Cyclic voltammetry (CV) and by using Chronopotentiometry (CP) the specific capacitance towered up to 512 Fg{sup −1} at a current density of 2.5 Ag{sup −1}. Further, the material also possesses a high energy density of 246 Wh kg{sup -1}with a maximum power density of 1028 W kg{sup -1}. GO-RuO{sub 2} nanostring composite electrode exhibits tremendous cyclic stability with the specific capacitance retention of nearly 99% of the initial capacitance.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2018

V2O5 nanowires-graphene composite as an outstanding electrode material for high electrochemical performance and long-cycle-life supercapacitor

Highlights: • V{sub 2}O{sub 5} nanowires anchored on the surface of rGO sheets using facile hydrothermal method for energy storage application. • High gravimetric capacitance of 1002 F g{sup −1} has been achieved at the current density of 1 A g{sup −1} in an aqueous electrolyte. • Exceptionally high energy density of 116 Wh kg{sup −1} has been obtained using supercapacitor coin cell. • Composite (V{sub 2}O{sub 5}-NW-G) exhibits excellent cyclic stability with 83.94 % capacitance retention after 5000 GCD cycles. - Abstract: A composite of V{sub 2}O{sub 5} nanowires with reduced graphene oxide (V{sub 2}O{sub 5}-NW-G) has been prepared using facile hydrothermal method and tested for charge storage supercapacitor application. Morphological and structural aspects of as prepared materials has been studied using material characterization techniques like transmission electron microscope (TEM), scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). The nanosized wires like structure of V{sub 2}O{sub 5} anchored on the graphene (rGO) sheets possesses improved electrical conductivity and high surface area. Electrochemical properties of the synthesized materials have been studied using cyclic voltammetry (CV), galvanostatic charge-discharge (GCD) and electrochemical impedance spectroscopy (EIS). Composite (V{sub 2}O{sub 5}-NW-G) exhibits exceptional properties like high gravimetric capacitance of 1002 F g{sup −1} along with good cyclic stability of 83.94% capacitance retention after 5000 repetitive GCD cycles. Excellent energy density of 116 Wh kg{sup −1} has been obtained at the power density of 1520 W kg{sup −1}.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2018

A progressive electrochemical sensor for food quality control: Reliable determination of theobromine in chocolate products using a miniaturized boron-doped diamond electrode

In the present paper, a miniaturized boron-doped diamond electrode (BDDE) is proposed as a progressive electrochemical sensor for simple, fast and reliable quantification of dimethylxanthine alkaloid, theobromine (TB). Using cyclic voltammetry, the studied xanthine provided one well-shaped, irreversible and diffusion-controlled oxidation peak at relatively high potentials (+1.2 V vs. Ag/AgCl/3 M KCl reference electrode) in the presence of 0.1 M H2SO4. After selection of suitable experimental conditions, the linear calibration curves for TB were obtained in the concentration range from 0.99 up to 54.5 μM with the sensitivity of 0.07 μA/μM providing both differential pulse (DPV) and square-wave voltammetric (SWV) techniques, respectively. The elaborated voltammetric protocol yielded low detection limits of 0.42 and 0.51 μM accompanied by adequate intra-day repeatability (relative standard deviation of 2.5 and 1.7%) using DPV and SWV procedure, respectively. The interference study revealed the reasonable selectivity when taking the target food samples into account. The practical applicability of the voltammetric protocol using a miniaturized BDDE was verified in the analysis of six commercially available brands of chocolate products with the determined mass percentages of TB ranging from 0.75 to 2.24% and from 0.69 to 2.15% using DPV and SWV procedure, respectively. The obtained results were also in a good agreement with those achieved by reference titration method with potentiometric indication. The progressive electrochemical sensor based on a miniaturized BDDE has appeared to be an attractive candidate for practical applications in food quality control. Besides, the proposed voltammetric protocol presents advantages when compared to others techniques (e.g. chromatography), concerning simplicity, cost, speed of analysis, waste generation (environmentally friendly) and samples pretreatment (only dilution in electrolyte solution prior to analysis). © 2018 Elsevier B.V.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2013

Nickel recovery from electronic waste II Electrodeposition of Ni and Ni–Fe alloys from diluted sulfate solutions

Highlights: • Ni can be recovered from EG wastes as pure Ni or as Ni–Fe alloys. • The control of the experimental conditions gives a certain alloy composition. • Unusual deposits morphology shows different nucleation mechanisms for Ni vs Fe. • The nucleation mechanism was progressive for Ni and instantaneous for Fe and Ni–Fe. - Abstract: This study focuses on the electrodeposition of Ni and Ni–Fe alloys from synthetic solutions similar to those obtained by the dissolution of electron gun (an electrical component of cathode ray tubes) waste. The influence of various parameters (pH, electrolyte composition, Ni{sup 2+}/Fe{sup 2+} ratio, current density) on the electrodeposition process was investigated. Scanning electron microscopy (SEM) and X-ray fluorescence analysis (XRFA) were used to provide information about the obtained deposits’ thickness, morphology, and elemental composition. By controlling the experimental parameters, the composition of the Ni–Fe alloys can be tailored towards specific applications. Complementarily, the differences in the nucleation mechanisms for Ni, Fe and Ni–Fe deposition from sulfate solutions have been evaluated and discussed using cyclic voltammetry and potential step chronoamperometry. The obtained results suggest a progressive nucleation mechanism for Ni, while for Fe and Ni–Fe, the obtained data points are best fitted to an instantaneous nucleation model.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2013

Cyclic voltammetric study of Co-Ni-Fe alloys electrodeposition in sulfate medium

Electrochemical technique has been used to study the electrodeposition of cobalt, nickel, iron and Co-Ni-Fe alloy on indium tin oxide (ITO) coated glass substrate. To obtain the nucleation mechanism, cyclic voltammetry is used to characterize the Co-Ni-Fe system. The scanning rate effect on the deposition process was investigated. Deposition of single metal occurs at potential values more positive than that estimated stability potential. Based on the cyclic voltammetry results, the electrodeposition of cobalt, nickel, iron and Co-Ni-Fe alloy clearly show that the process of diffusion occurs is controlled by the typical nucleation mechanism.

36 MATERIALS SCIENCE↗
DOE OSTI2014

Stable organic field-effect-transistors with high mobilities unaffected by supporting dielectric based on phenylene-bridged thienobenzothiophene

We report on the electrical properties of organic field-effect transistors (OFET) based on a new class of organic semiconductors. The molecules consist of the same thieno[2,3-b][1]benzothiophene building blocks, connected by different π-bridge spacers (ethylene, phenylene, and fluorophenylene). Molecular orbitals and highest occupied molecular orbital/lowest unoccupied molecular orbital energies were calculated and compared with results from cyclic voltammetric and UV-vis absorption measurements. In order to study the influence of the bridge groups on the molecular arrangement and surface interaction, the transistor performance on a wide range of dielectrics has been investigated in detail. These include as grown SiO{sub 2} and Al{sub 2}O{sub 3} and also treated with octadecyltrichrolosilane and octadecylphosphonic acid, as well as Cytop and Parylene C. An extended study of the multitude of combinations of these materials revealed mobilities up to ∼1 cm{sup 2}/Vs, measured for devices made of the phenylene-bridged compound. Surprisingly, the mobility was quite independent of the supporting gate dielectric. Stability over time has been observed with no degradation after 5 months. By eliminating the hysteresis using Cytop, we were able to show that some of the molecules form films without long-term charge carrier trapping. These are interesting features for practical industrial processing of organic electronics.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗