A Ti substrate was pretreated with an electron beam (E-beam) at RF 150 W and DC 1500 V for 1 h under Ar atmosphere and then anodized in a 1 M H3PO4/1 M NaOH/0.5 wt% HF solution at 20 V. The E-beam pretreatment led to a change in the composition surface, resulting in delayed nucleation of the nanotubes at the beginning of the anodization but a thicker oxide formation at the end of anodization because of the initial formation of a protective oxide that prevents the dissolution of the formed nanotubes in the electrolyte. (C) 2015 The Electrochemical Society.
The complex electrochemical impedance spectra of tungsten - (KCl-LiCl) interface at 700-800 degrees C consist of two well-separated semicircles. One at high frequencies and reflects charge transfer resistance and interfacial capacitance. The second is at low frequencies and is attributed to the electrical properties of the melt. Similar spectra are measured for tungsten - (KCl-NaCl) interface. The low-frequencies semicircle though is reduced above 750 degrees C. Entropy estimations from cyclic voltammetry measurements indicate an increase in the entropy of KCl-NaCl at similar to 750 degrees C and a possible change in the inter-ionic order and interactions. Asymmetric anion polarization interactions are suggested to be involved. (C) 2014 The Electrochemical Society. All rights reserved.
A copper electroplating using single JGB additive was developed for through silicon via (TSV) filling. The micro-vias were perfectly void-free filled by single JGB additive. The electrochemical analysis demonstrated a "bottom-up" deposition mode by single JGB additive. The "V" shaped filling was attributed to JGB gradient suppressing effect along the micro-via depth. The filled microstructure by single JGB mainly contained fine equiaxed grains while the filled microstructure by PEG-SPS additive contained large columnar grains.
An integral investigation about the preparation of cellular carbons from the decomposed cuttlefish bone (CB) and their carbonization, graphitization and electrochemical performances in electrical double layer capacitors are presented. Cellular carbons with a closed pore structure are obtained via the carbonization of the CB and they are graphitized in molten sodium metals at 800 C. Their specific surface area, average pore volume and specific capacitance are obviously improved after the graphitization. The results indicate that some natural carbon sources with an unordinary natural structure can own excellent electrochemical performances after the graphitization. (C) 2015 The Electrochemical Society. All rights reserved.
Formation and distribution of infiltrated electrocatalyst were controlled through solution chemistry and correlated cathode performance was investigated for a La0.6Sr0.4Co0.9Pt0.1O3-infiltrated solid-oxide fuel cell (SOFC). Selection of solvent and polymeric additives constituting the slip dramatically affected the infiltrate particles' spatial configuration, and finally determined cathode activity under cell operational conditions. The results imply that microstructural features such as 3-dimensional distribution and interconnectivity of infiltrated nanoparticles must be considered when evaluating activity and stability of cathodes. A modified infiltration process utilizing a mixed solvent of low surface tension and functionally sequenced infiltration was effectively applied to manipulate cathode microstructure. (C) 2015 The Electrochemical Society.
We investigated the structural features of gallium-nitride-porous structures formed using the photo-assisted electrochemical process in the back-side illumination (BSI) mode. The pore diameter and depth were strongly affected by the direction of illumination, where higher controllability was achieved compared with front-side illumination. The spectroscopic measurements revealed that illumination with photon energy below the bulk bandgap plays an important role in pore formation. We propose a formation model by considering the Franz-Keldysh effect that can consistently explain the obtained experimental data in which anodic etching occurs only at the pore tips under the high electric field induced in the depletion region.
In this letter we combine detailed electrochemical impedance measurements with quantitative measurements of O-2 evolution and Li2O2 oxidation to describe the charge mechanisms during charge of Li-O-2 batteries with porous carbon electrodes. We identify Li2O2 oxidation at 3.05 V and an apparent chemical formation of a solid electrolyte interface (SEI) layer as the first monolayer of Li2O2 is oxidized, leading to a voltage increase. The first electrochemical degradation reaction is identified between 3.3 V and 3.5 V, and the chemical degradation is limited above 3.5 V, suggesting that a chemically stable SEI layer has been formed. (C) 2015 The Electrochemical Society. All rights reserved.
RuO2 nanosheets were studied as a promotor for the hydrogen oxidation reaction in the presence of 300 ppm CO/H-2. The hydrogen oxidation current in 300 ppm CO/H-2 for RuO2 nanosheet modified PtRu/C catalyst (RuO2:Pt:Ru = 0.5:1:1 (molar ratio)) exhibited higher CO tolerance than Pt1Ru1/C and Pt2Ru3/C. Based on hydrodynamic voltammetry, chronoamperometry and CO stripping voltammetry, the addition of RuO2 nanosheets is suggested to suppress CO adsorption on the catalyst surface, resulting in an improvement in CO tolerance. (C) The Author(s) 2015. Published by ECS.
MgO-templated mesoporous carbon was investigated as an anode material for Na-ion storage. The mesoporous carbons exhibited a discharge capacity of 180 mAh g(-1) at a current density of 0.1 A g(-1) in a potential range of 2.00-0.01 V vs. Na+/Na. This capacity was comparable to that of commercial hard carbon materials. They also showed an outstanding rate capability: 70 mAh g(-1) at 4 A g(-1), which was 10-fold greater than the corresponding capability of commercial hard carbons. These results indicate that MgO-templated mesoporous carbon is a potential new anode material for high-power-density Na-ion batteries and capacitors. (C) 2014 The Electrochemical Society. All rights reserved.
A general surface-enhanced Raman spectroscopy (SERS) detection method was established through the one-step fabrication of a composite nanostructure of substrate and analyte to enable extremely sensitive biochemical detection. Compared with commonly used stepwise SERS detection techniques, our method can effectively increase detection sensitivity because of the enrichment effect. Results showed that the lowest detection limit of our method was 10(-13) mol/L (for Rhodamine B), which was higher by five magnitudes than that obtained by stepwise detection. Our method was also easy to operate and cost effective, thereby showing potential application in trace analyses of biochemical analytes. (C) 2015 The Electrochemical Society. All rights reserved.
Void-free filling of TSV-scaled trenches is achieved by adding a new leveler with an accelerator and polymeric suppressor. Leveler containing two quaternary ammonium salts allows for the galvanostatic bottom-up filling. In addition, the filling time is reduced by applying the step current comprising a first step to establish a growing surface and a second step to reduce the filling time. The deposition height of the growing surface during the first step critically determines the filling performance. By modulating the step condition, the filling time reduced by 47% compared to the constant current deposition. (C) The Author(s) 2015. Published by ECS. This is an open access article distributed under the terms of the Creative Commons Attribution Non-Commercial No Derivatives 4.0 License (CC BY-NC-ND, http://creativecommons.org/licenses/by-nc-nd/4.0/), which permits non-commercial reuse, distribution, and reproduction in any medium, provided the original work is not changed in any way and is properly cited. For permission for commercial reuse, please email: oa@electrochem.org. All rights reserved.
A superhydrophobic phosphate/fatty-acid salt compound coating (PFASCC) was fabricated via a phosphate chemical conversion treatment of AZ91D magnesium alloy and subsequent electrodeposition. The rough surface of phosphate conversion coating (PCC) containing intrinsic micropores and microcracks can favor the growth of the fatty-acid salt layer. The formation of the fatty-acid salt layer occurs via reaction between tetradecanoic acid as well as stearic acid and Ce3+ cations at the solution/phosphate conversion layer interface. The PFASCC, which is mainly composed of Ce(CH3(CH2)(12)COO)(3), Ce(CH3(CH2)(16)COO)(3) and phosphate, exhibits good superhydrophobic properties and better corrosion resistance than the hydrophilic PCC. (C) 2015 The Electrochemical Society. All rights reserved.
Chronoamperometric analysis of the oxygen reduction reaction (ORR) at Pt microelectrode vertical bar perfluorosulfonic acid (PFSA) ionomer interfaces in a solid state electrochemical cell reveals an increase in both the oxygen diffusion coefficient (D-b) and oxygen permeability (D(b)c(b)) upon consecutive potential step measurements. From a vapor-equilibrated, electrochemically unperturbed state under conditions of 70% RH and 50 degrees C, D-b and D(b)c(b) increased by factors of 2 and 1.5, respectively. D-b and D(b)c(b) return to their initial values after resting the electrode at the open circuit potential. The electrochemical generation of water is believed responsible for the time-dependent mass transport parameters of ORR. (C) The Author(s) 2014. Published by ECS. This is an open access article distributed under the terms of the Creative Commons Attribution Non-Commercial No Derivatives 4.0 License (CC BY-NC-ND, http://creativecommons.org/licenses/by-nc-nd/4.0/), which permits non-commercial reuse, distribution, and reproduction in any medium, provided the original work is not changed in any way and is properly cited. For permission for commercial reuse, please email: oa@electrochem.org. All rights reserved.
The aluminum-doped ZnO/Ru composite (AZO/Ru) was developed as a carbon-free cathode material for Li-air batteries for the first time. The AZO was synthesized by the fast and convenient microwave-assisted hydrothermal method and Ru was added as a catalyst to improve the electrochemical performance of the AZO/Ru. Adjusting the synthesis conditions can produce enhanced surface properties which affect the electrochemical properties of the AZO/Ru. Experimental results confirmed that formation of Li2CO3 can be suppressed by an AZO/Ru cathode and established its applicability as a potential cathode material for Li-air batteries. (C) 2015 The Electrochemical Society. All rights reserved.
A challenge for magnesium ion battery research is the development of electrolytes that are capable of reversible magnesium electrodeposition through multiple cycles. Magnesium alkoxide chlorides and aryloxide chlorides are known magnesium ion electrolytes when used in conjunction with aluminum chloride. Herein we report the effects of structural variation in several dialkoxy and diaryloxy magnesium complex aggregates with aluminum chloride, Mg(OR)2:AlCl3 (R = iPr, t-Bu, phenyl), on electrochemical characteristics of their solutions and on compositions of the magnesium-containing deposits they yield. We also report the synthesis of a magnesium phenoxide-based electrolyte directly from magnesium metal. © The Author(s) 2015. Published by ECS. This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 License (CC BY, http://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse of the work in any medium, provided the original work is properly cited. [DOI: 10.1149/2.0031506eel] All rights reserved.
In solid-state alkaline fuel cells, anion exchange membrane fuel cells without free alkali, Mg-Al type layered double hydroxide (LDH) and fractionally delaminated LDH (dLDH) were introduced in the catalyst layer to explore the use of an inorganic anionic clay as a non-swelling durable electrolyte. An improved current-voltage performance was obtained by the LDH introduction due to the formation of ionic conduction pathways, whereas the dLDH introduction resulted in the disruption of the electron conduction pathway and the contact between dLDH and the catalyst, leading to a deteriorated performance. The results provide guidelines for utilizing inorganic clays as solid electrolytes. (c) 2015 The Electrochemical Society. All rights reserved.
To develop an electrorefining process for sodium to enable recycling of used sodium-sulfur batteries, a non-aqueous electrolyte with low melting point was investigated. A mixed ionic liquid of NaTFSI (sodium bis(trifluoromethane) sulfonylimide) - TBATFSI (tetrabutylammonium bis(trifluoromethane) sulfonylimide) was selected for the electrolyte. From AC impedance measurements, a maximum ionic conductivity of 16 mS cm(-1) was established of 20 mol% NaTFSI-TBATFSI concentration at 433 K. Electrorefining for 20 hours was carried out with a stable voltage under constant current electrolysis. Liquid pure sodium was electrodeposited by the constant current electrolysis. The calcium content in the sodium cathode was decreased from 250 to 52 ppm by the electrorefining. (C) 2014 The Electrochemical Society. All rights reserved.
We demonstrate the possibility to cover the surface of GaP and InP porous structures by a self-assembled monolayer of electrochemically deposited nanoscale Au nanodots. After nucleation, each dot was found to increase in sizes up to a critical transverse dimension, the process of pulsed electrodeposition of gold being continuously supported by the formation of new nanodots. The density of deposited Au dots is shown to be dependent upon the number and width of the applied voltage pulses. The deposition of "size-saturated" dots continues until the entire surface exposed to the electrolyte is covered by a monolayer of self-assembled Au nanodots.
A CeO2 supported membrane electrode assembly (MEA) was fabricated by hot-pressing CeO2-coated electrodes and a PFSA ionomer membrane. Upon application of a combined chemical and mechanical accelerated stress test (AST), the CeO2 supported MEA showed six times longer lifetime and 40 times lower fluoride emission rate than a baseline MEA without cerium. The membrane in the CeO2 supported MEA effectively retained its original thickness and ductility despite the highly aggressive AST conditions. Most of the cerium applied on the anode migrated into the membrane and provided excellent mitigation of joint chemical and mechanical membrane degradation.
