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Abstract With the legalization of recreational cannabis use, there is a need to develop a rapid and accurate roadside test that can be used to analyze human saliva samples for Δ9-tetrahydrocannabinol (THC), the main psychoactive ingredient in cannabis. Here we demonstrate a novel drug detection method where THC is infused into carbon paper electrodes followed by electrochemical detection in a pH 10 aqueous solution. This method produces a linear, sensitive (down to ∼ 1 pmol), dose-dependent change in the oxidation peak current that varies with THC surface densities. These results, as well as the peak charge per real carbon surface area and linear current/scan-rate dependence, support a model for the distribution of THC on the carbon surface in a thin-layer configuration, facilitating the oxidation of the deposited drug. We also demonstrate electro-oxidation of the two major metabolites of THC, the psychoactive 11-hydroxy-tetrahydrocannabinol (OH-THC), and the non-psychoactive 11-nor-9-carboxy-tetrahydrocannabinol (COOH-THC), that also produce linear, dose-dependent changes in peak charge. However, COOH-THC exhibits a much lower Faradaic efficiency than OH-THC and THC, suggesting that variations in the THC functional groups affect the electro-oxidation of the cannabinoids. Overall, this work illustrates a novel, reproducible, and sensitive method for the analysis of THC and oxidation properties of its common metabolites that could be adapted for use with human saliva samples in future work. [ABSTRACT FROM AUTHOR]

• First use of graphite and polycaprolactone composite electrode for electrochemical study of NBOHs;. • Proposal of a mechanism for the oxidation of 25H-NBOH and 25B-NBOH using cyclic voltammetry. • Quantification of 25H-NBOH and 25B-NBOH in synthetic urine and blotting paper without the need for complex sample preparation. The dramatic escalation in the quantity of new synthetic drugs in recent years has prompted the pursuit of novel methods for identifying and quantifying these substances. Notably among them are the substituted phenethylamines known as NBOHs and NBOMes. Electrochemical study and quantification of new psychoactive substances (NPS) 25H-NBOH and 25B-NBOH in synthetic urine and synthetic blotting papers are presented using differential pulse voltammetry (DPV) on a composite electrode (CE) made of graphite and polycaprolactone (PCL). Based on the cyclic voltammetry (CV) results, we propose that the drug oxidation mechanism comprises two main steps. Initially, it involves the oxidation of the secondary amine, necessitating the removal of one electron from the amino-nitrogen atom, leading to dealkylation. Subsequently, bromine or methoxy substitution takes place. Under the optimized experimental conditions for the differential pulse voltammetry (DPV) studies, analytical curves were obtained in the range of 100 to 800 ng mL−1 for 25H-NBOH and 100 to 700 ng mL−1 for 25B-NBOH (r² = 0.999), with detection limits of 19 ng mL−1 and 23 ng mL−1, respectively, and quantification limits of 64 ng mL−1 and 76 ng mL−1. The proposed method was employed for quantification of the drugs in synthetic urine and synthetic blotting papers, with recovery values between 95 % and 106 %, demonstrating no interference from the matrices. [Display omitted] [ABSTRACT FROM AUTHOR]

Abstract In this study, cathodic electrodeposition of manganese oxide onto reduced graphene oxide paper is carried out to prepare flexible and binder-free electrodes for electrochemical capacitors. Effects of electrodeposition potential and the amount of deposited mass on the electrochemical performance are examined. Hausmannite phase manganese oxide coated electrodes exhibit promising performance in charge-discharge and cyclic voltammetry measurements with specific capacitance of 546 F g−1 at current density of 0.5 A g−1 and 308 F g−1 at scan rate of 1 mV s−1, respectively. During potential cycling, phase transformation of Mn 3 O 4 to mixed-valent MnO x is observed. Consequently, MnO x nanostructures on self-standing reduced graphene oxide electrodes have 154% capacitance retention at 10000 cycles of cyclic voltammetry. Graphical abstract Image [ABSTRACT FROM AUTHOR]

Due to highly conducting and extraordinary stable nature, carbon based materials expand the arms of energy storage devices in terms of supercapacitor. Hence, emphasis has been made to use flexible and free-standing multi-walled carbon nanotubes (MWCNTs) bucky paper synthesized by chemical vapor deposition for electrochemical supercapacitive electrode. The high specific capacitance of 270 F/g (2 mV/s) with superb stable behavior (88% at 10000 cycles) of bucky paper has promised as decent electrode in energy storage application. Aqueous symmetric supercapacitor (ASSC) device developed through bucky paper exhibits voltage frame of 1.6 V yielding specific capacitance of 91 F/g along with specific energy of 32 Wh/kg at a current density of 1 mA/cm 2 with trustworthy stability of 107% at 6000 cycles. The hands-on practicability to light up a red LED offers its promising approach in energy storage domain. [ABSTRACT FROM AUTHOR]

A simple and inexpensive procedure of paper-based electrode (PE) fabrication using A4 size conventional paper, nail polish and carbon powder is reported. The device was prepared by spreading the carbon conductive ink directly onto the paper substrate using a paint-brush. The best composition of the conductive ink was 80:20% (m:m) carbon powder: nail polish and the best device was obtained with 100 mg (2.5 mg cm −2 ) of carbon conductive ink spread on the paper piece. The proposed device showed satisfactory stability in acidic, neutral and alkaline medium in presence of ferrocyanide ion used as electrochemical probe. Dopamine was selected as a target compound to evaluate the possibility of using the proposed device for electroanalytical purposes. Differential pulse voltammetry was used in these studies and dopamine detection was achieved at +0.13 V vs. Ag/AgCl sat in phosphate buffer solution pH = 7 with a detection limit of 5.2 μmol L −1 . The proposed device represents an interesting advance in the field of PE construction since it combines satisfactory electrochemical stability and electroanalytical performance with simplicity and widely available low-cost materials. Moreover, chemical modifiers can be easily added to the conductive ink. Therefore, this versatile device brings exciting possibilities for future electroanalytical applications mainly for those that require small and/or flexible devices, such as the amperometric detection in microfluidic systems. [ABSTRACT FROM AUTHOR]

We propose here a quick and easy procedure for preparing pencil leads doped with Ag and AgCl suitable for the reproducible and easy drawing on paper or other porous supports of carbon based Ag/AgCl conductive lines for the use as reference electrodes. They were prepared by careful electrodeposition of silver and silver chloride on carbon powder (conductive material) which was then mixed with sodium bentonite (binding agent) and sodium silicate (hardening agent). Extrusion at room temperature of these mixtures from a suitable die allowed thin rods to be obtained, which were then inserted in commercial lead holders to facilitate their use for drawing electrodes on paper. Their performance was evaluated by voltammetric measurements conducted by using hexacyanoferrate(II) and 1,2-hydroxybenzene as probe species known to display a reversible electrochemical behaviour. The results found pointed out that the potential exhibited by these drawn reference electrodes was fully reliable only when small but controlled amounts of chloride ions can be added to assayed samples, without interfering investigated processes. Conversely, a poorer reliability characterise these reference electrodes when chlorides cannot be added, in that they display potentials higher of about 100–150 mV than their theoretical value. Their reproducibility (± 0.02 V), controlled on a series of different PEDs wetted with the same sample, was however so narrow for voltammetric investigations as to make their use preferable to usual pseudo-reference electrodes whose potential is remarkably affected by the different components present in assayed samples. [ABSTRACT FROM AUTHOR]

Lithium-sulfur (Li-S) battery with new configuration is demonstrated by inserting a flexible activated carbon nanofiber (ACNF) interlayer between the sulfur cathode and the separator. The ACNF with tunable pore structure is fabricated by a combination of electrospinning polyimide and a subsequent activation treatment. The influence of the textual characteristics of ACNFs on the electrochemical performance of Li-S batteries has been studied. The highly porous ACNF not only effectively intercepts/stabilizes the shuttling migration of polysulfides within the cathode region, but also provides reliable ionic/electronic conductivity for fast kinetics. The lightweight ACNF interlayer with higher specific surface area can yield enhanced cell performance at a low mass ratio of ACNF/sulfur (0.4). An initial specific capacity of 1224 mAh g −1 along with high Coulombic efficiency, long cycling stability and good rate capability is achieved in the modified Li-S cell. [ABSTRACT FROM AUTHOR]

Ferrocenyl aniline is an excellent catalyst used conventionally for heterocyclic syntheses. The use of ferrocenyl aniline, in the presence of electropolymerized thiophene-3-acetic acid (TAA) on carbon fibre paper is novel and found to be an exceptional electrocatalyst, for the synthesis of a proven anti-fungal, anti-proliferative and anti-bacterial, 2-(4-methoxyphenyl)-1 H -benzo[ d ]imidazole. The electrode performance was examined with activity studies and EIS, along with surface characterizations including optical profilometry, FE-SEM, FT-IR and XPS. The synthesis was performed in a single-cell three electrode system, using platinum as counter and saturated calomel electrode (SCE) as the reference, with ethanol as the electrolyte and lithium perchlorate supporting electrolyte. The reaction was performed with o- phenylenediamine and anisaldehyde as starting materials at ambient temperature and pressure, at 1.35 V constant potential for 3 h, and product was isolated and purified using column chromatography to obtain 91% yield and characterized with GC–MS and NMR. This synthesis method is noteworthy, due to its environmentally friendly performance, and high yield for a benzimidazole derivative that is pharmacologically vital. [ABSTRACT FROM AUTHOR]

Mn 0.5 Ti 2 (PO 4) 3 with a NASICON structural is used as an anode material in potassium-ion batteries due to its abundance of vacancies that can hold potassium ions. This characteristic not only contributes to its excellent stability but also results in a high specific capacity. However, the poor electrical conductivity of the polyanionic type structure limits the material's ability to fully utilize its capacity. In this paper, the conductivity and electrochemical stability of the Mn 0.5 Ti 2 (PO 4) 3 anode material are enhanced through composite formation with an F-doped carbon layer. The introduction of F into the carbon matrix creates a large number of vacancy defects and F active sites. The vacancies enhance the transport of potassium ions on the Mn 0.5 Ti 2 (PO 4) 3 material's surface, while the active sites exhibit strong electronegativity, improving the absorption of potassium ions. Therefore, the diffusion impedance of potassium ions is significantly reduced, leading to an increased diffusion rate of potassium ions. Attributing to the improved reaction kinetics, the Mn 0.5 Ti 2 (PO 4) 3 @F-doped carbon composite demonstrates a high specific capacity of 86 mA h g−1 at 10,000 mA g−1 when used as the anode for potassium-ion batteries. Even more, the specific capacity remains a capacity of 136 mA g−1 after 3000 cycles at 1000 mA h g−1. This study enhances our comprehension of material design by investigating the alteration of carbon matrix to promote the electrochemical characteristics of materials. [ABSTRACT FROM AUTHOR]

In this paper, we report a novel Sn/G/RGO-S battery with high capacity and good cycle life in comparison to conventional lithium-ion batteries. Low cost electroplating and drop cast method are developed for the first time to prepare binder free highly porous 3D Sn/G/RGO composite on carbon paper substrate as anode. The unique 3D porous network of Sn/G composite allows better accommodation of volume expansion induced by Li insertion, while presence of graphene in the co-electrodeposited Sn/G composite provides enhanced electron conduction. Additional coating of RGO on the surface of co-electrodeposited Sn/G composite protects the electrode surface from the direct electrolyte contact, and minimizes the progressive SEI formation during repeated charge-discharge cycles. Consequently, Sn/G/RGO electrode in half-cell exhibits a much superior electrochemical performance and better cycle life. We also demonstrate a full-cell by using S/C as cathode and Sn/G/RGO composite with a very thin lithium foil on the surface as anode in order to avoid serious safety issues allied with lithium metal. Sn/G/RGO-S full cell delivers a high discharge capacity of 413 mAh g −1 at the end of 40 cycles. The cell delivers a specific energy of about 660 Wh kg −1 based on the weight of sulfur and 336 wh kg −1 based on the total mass of the S/C electrode. The simple designed and cost effective technique to fabricate high performance Sn/G/RGO-S battery would be feasible for alternative clean energy sources. [ABSTRACT FROM AUTHOR]

The integration and mass-production of reference electrodes for CMOS-based electrochemical sensing systems pose a challenge for the accessibility and commercial-viability of such devices. In this paper, a method of electroplating an Ag/AgCl quasi-reference electrode using CMOS top-metal as a base is presented for the first time. The aluminium bond-pad of a CMOS microchip was zincated, an electroless nickel immersion gold layer applied, and a thick silver layer electroplated and chemically chlorinated. The resulting reference electrode was able to provide a stable potential with a drift rate of 0. 3 mV/h for up to 18 h. This validates the approach of a fully electroplated bond-pad reference electrode, which offers simplified post-processing and greater scalability of production. Further work towards an entirely electroless process is envisaged. [ABSTRACT FROM AUTHOR]

As the cathode material of lithium-ion batteries, Li-rich ternary layered oxides usually suffer from high first cycle irreversible capacity, low rate capability, and structural instability during charge–discharge. Recent studies show that Ni-rich Li 1.20 Mn 0.44 Ni 0.32 Co 0.04 O 2 material has good structural stability. In this paper, the electrochemical performance of Li 1.20 Mn 0.44 Ni 0.32 Co 0.04 O 2 and its oxygen-deficient phase Li 1.20 Mn 0.44 Ni 0.32 Co 0.04 O 1.83 are studied by the first-principles calculations. The results show that, for the pristine phase Li 1.20 Mn 0.44 Ni 0.32 Co 0.04 O 2 , the theoretical delithiation capacity is 380 mAh/g and the highest charging voltage platform is 4.99 V. The O ions are found to participate in the charge compensation significantly. Ni ions can only contribute 118 mAh/g of the delithiation capacity, and the remaining charging capacity is contributed by O ions. For the oxygen-deficient phase Li 1.20 Mn 0.44 Ni 0.32 Co 0.04 O 1.83 , the highest voltage platform is reduced by 0.21 V, O ions are also found to participate in the charge compensation obviously. Compared to the pristine phase, transition metal (TM) ions in the oxygen-deficient phase exhibit higher chemical activity, while the contribution of O ions to charge compensation is relatively reduced. The oxygen-deficient phase has a slightly higher theoretical capacity (392 mAh/g) than the pristine phase. [Display omitted] [ABSTRACT FROM AUTHOR]

Titanium nitride nanoparticles (TiN NPs) are proposed as a novel catalyst towards the V(II)/V(III) redox pair for the negative electrode in vanadium redox flow batteries (VRFB). Electrochemical properties of TiN NPs were characterized by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The results show that TiN NPs demonstrate better electrochemical activity and reversibility for the processes of V(II)/V(III) redox couples as compared with the graphite NPs. TiN NPs facilitate the charge transfer in the V(II)/V(III) redox reaction. Performance of a VRFB using a TiN NPs coated carbon paper as a negative electrode is much higher than that of a VRFB with a raw carbon paper electrode. The columbic efficiency (CE), the voltage efficiency (VE) and the energy efficiency (EE) of the VRFB single cell at charge-discharge current density of 30 mA/cm 2 are 91.74%, 89.11% and 81.74%, respectively. During a 50 charge-discharge cycles test, the CE values of VRFB with TiN NPs consistently remain higher than 90%. [ABSTRACT FROM AUTHOR]

• The 3D microflower-like V 2 O 5 ·4VO 2 with Ga-doped cathode is synthesized by a green hydrothermal method. • Combining the two modification methods of constructing three-dimensional micro-nanostructures and metal ion doping to enhance the electrochemical performance of V 2 O 5 ·4VO 2. • The prepared GVO2 with Ga-doped exhibits both a high specific capacity (as high as 322.47 mAh·g−1 at 0.1 A·g−1), excellent high rate performance (224.72 mAh·g−1 at 1 A·g−1) and favorable cycling stability with 81.09 % capacity retention. Within various lithium-ion batteries (LIBs) cathode materials, vanadium oxides are considered to be a potential candidate for the next-generation LIBs cathode materials owing to their abundant reserves, low cost and higher theoretical specific capacity. However, its inferior structural stability leads to suboptimal cycling stability as vanadium oxides are used as cathode materials for lithium-ion batteries. Metal ions and 3D microstructure engineering are considered to be an effective method which is used to enhance the electrochemical performance of cathode materials for lithium-ion batteries. In this paper, the 3D microflower-like V 2 O 5 ·4VO 2 with Ga-doped is synthesized with Ga(NO 3) 3 as the gallium source. The appropriate amount of Ga ion doping does not only optimize the microscopic morphology of the samples but also extends the cell volume of V 2 O 5 ·4VO 2 , so as to increase the conductivity and lithium ion diffusion coefficient of the electrode materials. At the Ga doping amount of n (Ga3+)/n (V5+)=4.54 %, the prepared 3D microflower-like V 2 O 5 ·4VO 2 with Ga-doped exhibits both a high specific capacity (as high as 322.47 mAh·g−1 at 0.1 A·g−1), excellent high rate performance (224.72 mAh· g −1 at a current density of 1 A·g−1) and favorable cycling stability (81.09 % capacity retention after 200 cycles at 1 A·g−1). Consequently, the 3D microflower-like V 2 O 5 ·4VO 2 with Ga-doped provides great development potential as a cathode material for next-generation LIBs. [Display omitted] [ABSTRACT FROM AUTHOR]

• A Box-Behnken design for graphite anodes slurries optimization was presented to highlight the importance of the component's interactions to obtained higher performed anodes of lithium-ion batteries customization. • The carbon black content is the most significant effect in both materials which is reflected in higher capacities and coulombic efficiencies. • For the overall behavior, the binder/carbon black interactions are relevant in terms not only of electrochemical performance but also in the obtention of more homogeneous and better adhesion anodes. The technological application of lithium-ion batteries (LIB) grows constantly, making customization of the batteries a current necessity and sometimes a challenge. In this paper we described carbon-slurry optimization process for anodes of lithium-ion batteries customization by using a surface response statistical experiment with four response variables such specific discharge capacity, coulombic efficiency, anodes mass deviation, and capacity retention. We studied two commercial graphite active materials by characterizing the materials via Raman spectroscopy, SEM, and electrochemical techniques. We corroborate the graphite structure for both materials but with morphological differences such as shape and particle size. The binder composition seems to interfere with the active carbon materials capabilities while it generates better performance for one of them. Although the chemical structure of both materials was confirmed to be the same via Raman experiments, SEM images shows critical morphological differences that interferes with the final slurry thus, affecting the electrochemical performance of the anodes. Further studies are required to understand ECSA and its possible effect on the charge/discharge capacities of the anodes. [Display omitted] [ABSTRACT FROM AUTHOR]

A novel (I + /I 2 )/vitamin C vs. V 4+ /V 5+ semi-vanadium redox flow battery (semi-VRFB) with iodine, vitamin C, and V 4+ /V 5+ redox couples, using multiple electrodes was investigated. The electrodes, Ni-P/carbon paper and Ni-P/TiO 2 /carbon paper, were modified by the electroless plating method and sol-gel process. The electrochemical characteristics and the performance of the semi-VRFB were verified by the cyclic voltammetry method and a charge-discharge test. This study shows modified electrodes can improve the reversibility and symmetry of the oxidation-reduction reaction of the semi-VRFB system, and effectively raise its storage ability. The coulomb efficiency of the semi-VRFB system is close to 96%, which is higher than the all-VRFB. The semi-VRFB system can reduce the amount of vanadium salt, therefore, it is not only a reduction in cost, but also has a great potential for the development of energy storage systems. [ABSTRACT FROM AUTHOR]

Proton-conducting solid oxide fuel cell is an electrical energy generation device with great potentials in the industrial and civil applications. The values of empirical parameters adopted in the corresponding simulations significantly determines the quality and reliability of the modeling results. Two new and practicable approaches are proposed in this paper, in order to accurately evaluate several critical electrochemical parameters in the relevant simulations. According to our models, effective hole conductivity of the electrolyte under working conditions, along with cathode electrochemical reaction order, are directly derived from the experiment. To examine the proposed approaches, single cells with BaCe 0.8 Sm 0.2 O 3- δ electrolyte and Sm 0.5 Sr 0.5 CoO 3- δ –BaCe 0.8 Sm 0.2 O 3- δ cathode are manufactured, further the related experiments are performed as case studies. To determine the cathode activation overpotentials for cells with different particle sizes, a transferable parameter named TPB-specific exchange current density is introduced, and an expression which is much more convenient for numerical simulation of the cathode activation overpotential than the previously reported one is put forward in our model. These proposed expressions and parameters possess desirable transferability, and accurate numerical predictions of the cell output performances are achieved for both our and reported experiments. Then the influences of the involved polarizations are explored. Emphasis is drawn on the electrolyte hole conductivity. Its impact on the cell performance is non-negligible particularly under relatively high temperature and low output current, and hence has to be considered seriously in the simulation. • Model to quantify electrolyte hole conductivity and cathode reaction order is built. • Laplace transform is firstly introduced to the model analysis of H-SOFC. • The model-predicted cell capacities accord well with our and reported experiments. • Transferable TPB-specific exchange current density is put forward. • Rate-determining step of cathode reaction can be deduced by our model. [ABSTRACT FROM AUTHOR]

Abstract In this paper, a gradient phosphate polyanion doping strategy is applied to enhance the electrochemical properties of LiNi 0.6 Co 0.2 Mn 0.2 O 2 cathode. This strategy synergistically achieves the gradient doping of phosphate polyanion and in-situ coating of Li 3 PO 4 layer. The gradient doping improves the cycling stability and rate performance of LiNi 0.6 Co 0.2 Mn 0.2 O 2. Especially, the capacity retention of P0.02-NCM sample is 92.9% at high cut-off voltage (4.5 V) and high temperature (55 °C), whereas the LiNi 0.6 Co 0.2 Mn 0.2 O 2 sample only shows lower capacity retention of 55.7%. The X-ray powder diffraction (XRD) and Fourier transform infrared spectrometry (FT-IR) results confirm that the large tetrahedral PO 4 3− polyanions are doped into oxygen layer for stabilizing the lattice structure. In addition, scanning transmission electron microscopy (STEM) and inductively coupled plasma (ICP-MS) analysis show that the Li 3 PO 4 layer availably inhibits the dissolution of transition metal ions (Ni, Co, Mn). Interestingly, the Li 3 PO 4 coating layer as a fast ion conductor also optimizes the Li+ diffusion coefficient. Such excellent results indicate that the surface gradient phosphate polyanion doping strategy is very valuable and useful to remarkably enhance the electrochemical properties of LiNi 0.6 Co 0.2 Mn 0.2 O 2 cathode at high cut-off voltage (4.5 V) and high temperature (55 °C). [ABSTRACT FROM AUTHOR]

Abstract The passivation issue of Fe 2 O 3 electrode has triggered off their low practical capacity, poor rate capability and cycling performance and thus limited their practical application as anodes for alkaline Ni-Fe batteries. This paper proposes a dual modification of Fe 2 O 3 by in-situ sulfurization and post carbon coating. Fe 2 O 3 -S nanorod arrays with a uniform sulfurization layer coated on Fe 2 O 3 core were firstly fabricated by in-situ sulfurization of Fe 2 O 3 nanorod arrays grown on Ti foil. After coating carbon on the Fe 2 O 3 -S arrays by PECVD process, Fe 2 O 3 -S@C were obtained. Electrochemical tests in alkaline electrolyte in the potential window of −1.2∼0 V show that the Fe 2 O 3 -S@C exhibited dramatically improved discharge capacity (60.5 times compared to Fe 2 O 3), cycling stability (92.2% for Fe 2 O 3 -S@C and only 7.9% for Fe 2 O 3 -S after 100 cycles) and excellent rate capability, owing to the co-contribution of the sulfurization layer and carbon layer. Furthermore, a Ni-Fe cell is assembled by pairing with a Ni 2 S 3 cathode, and delivers high energy/power density (45.64 Wh/kg at 1.3 kW/kg and 27.14 Wh/kg at 10.3 kW/kg). [ABSTRACT FROM AUTHOR]

To compound with conductive agents is the common strategy to address the low electric conductivity of redox conversion type anode materials; however, it brings on the complex techniques and thus increases the practical cost. This paper reports a less efficiency-cost method through partial element substitution which can significantly enhance the electric conductivity of the host materials. Specifically, partial Ni substitution into MnCO 3 with different x values, corresponding to Ni x Mn 1- x CO 3 porous submicrospheres ( x  = 0, 0.2, 0.25, 0.33), were fabricated through one-pot solvothermal route and tested as anode materials for lithium ion batteries (LIBs). The substitution of Ni in the composites mainly serves as the following objectives: increasing the electric conductivity and improving the structural integrity. By comparison, the Ni x Mn 1- x CO 3 sample at x  = 0.25 value shows the optimal electrochemical behaviors: it delivers specific capacities of 709 mAh g −1 for 500 th cycle at a high rate of 1.0 A g −1 , and 549 mAh g −1 for 1000 th cycle at 2.0 A g −1 ; more impressively, it also shows an excellent rate performance, exhibiting a 509 mAh g −1 at 5.0 A g −1 during the rate capability testing. These results demonstrated a cost-efficient way to ameliorate conversion-type negative electrode materials with high capacity and long life-span in LIBs. [ABSTRACT FROM AUTHOR]

This paper reports the experimental feasibility of using VO 2 (B) nanomaterial as a high-capacity, high-voltage, and promising performance cathode material for magnesium-ion battery. Recent research on monoclinic VO 2 (B) material in the prevailing lithium-ion batteries has attracted more and more interest, primarily due to the layered structure and large charge/discharge capacity of the material. We synthesized VO 2 (B) in both forms of nanorods and nanosheets via a facile hydrothermal method to use as the cathode for an Mg ion battery, and investigated their properties, and electrochemical performance and mechanism with SEM, FT-IR, XRD, XPS, ICP and the electrochemical technique. . An encouraging performance is achieved with VO 2 (B) in the form of nanorods instead of nanosheets. The VO 2 (B) nanorods are capable of operation with a high discharge voltage at 2.17 V vs. Mg 2+ /Mg and a high initial discharge specific capacity of 391 mAh/g at a voltage ranging from −1.00 V to 0.30 V vs. Ag + /Ag, corresponding to 0.61 mol Mg per unit at a current density of 25 mA/g at 20 °C. Even at 12 °C, the first discharge specific capacity of 394 mAh/g is obtained with a capacity retention ratio up to 52.2% after 60 cycles at 50 mA/g, showing a better cyclability and capability. Significantly, the VO 2 (B) nanorods are confirmed to be a promising cathode material for use in Mg rechargeable batteries of a high capacity and a high voltage. [ABSTRACT FROM AUTHOR]

It was recently demonstrated that a highly soluble amorphous carbon based material (EHC-electrogenerated hydrophilic carbon based material) is produced simultaneously at the anode ( a -EHC) and cathode ( c -EHC) of graphite. In this paper we compare their grade of amorphicity by Raman and their electrochemical properties. For the latter purpose, it was evaluated the potential window, the presence of electrochemically reducible and oxidizable functional groups, the capacitive properties and the electrocatalytic activity towards the oxygen and peroxide reduction reaction in the neutral medium. It was also used Fe(CN) 6 3−/4− , Ru(NH 3 ) 6 3+/2+ and Fe 3+/2+ redox probes to measure the heterogeneous electron transfer (HET) rate. It was found that a -EHC material is the less amorphous material, demonstrating a higher capacitance (120 μF cm −2 ), higher amount of reducible and oxidizable functional groups, higher ability for the H 2 O 2 reduction (180.7 and 4.3 μA cm −2 mM −1 sensitivity at −1.1 V and at −0.50 V, respectively) and superior catalytic activity for the ORR (17 A g −1 at −0.30 V). Both EHC materials possess a wide potential window and exhibit a HET rate consistent with the surface charge and the different amount/nature of oxygen functionalities on the surface electrode material. This works reveals that EHC materials, in particular a -EHC, show a high potential for a wide range of technological applications in biosensing field and energy conversion and storage devices. [ABSTRACT FROM AUTHOR]

This paper aims to demonstrate a novel electrochemical energy storage device, a hybrid Na-ion capacitor with organic electrolyte. Sodium manganese oxide having formula Na 0.4 MnO 2 has been chosen and synthesized as the most suitable battery-type positive electrode, while activated carbon (AC) has been utilized as the capacitor-type negative electrode. Due to the application of propylene carbonate based organic electrolyte, the maximum safe operating voltage of the device has been established as high as 2.7 V, giving rise to a specific capacitance of 17.4 F g −1 , significantly higher as compared to the analogous symmetrical EDLC measured in our laboratory based on AC electrodes in the same electrolyte. [ABSTRACT FROM AUTHOR]

The solvation of anions with organic solvent and its electrochemical intercalation into graphite is a significant research orientation in the electrochemical energy storage. Butylene carbonate (BC), a common solvent with higher oxidation resistance compared with ethylene carbonate (EC) and propylene carbonate (PC), is profitable in studying anion-graphite intercalation compounds (AGICs). In this paper, the electrochemical intercalation behaviors of three representative anions (BF 4 − , ClO 4 − and PF 6 − ) in BC solution were studied and the solvation states of these anions were characterized by electrochemical in situ and ex situ techniques. The interpretation of results illuminated that all three anions were able to intercalate into graphite with the similar reversibility but different solvation state, and the conclusive role that solvent played in the intercalation process was also discovered. [ABSTRACT FROM AUTHOR]

In this paper, a powerful photoconductive interfacial layer was achieved by employing Cd 2 SSe / ZnS quantum dots (CSSQDs) to modify the electron-transport layers (ETLs) in polymer solar cells (PSCs). With the optimal concentration of CSSQDs and superior film process condition, the power conversion efficiency (PCE) was increased from 4.12% to 6.49% for P3HT:ICBA based device, leading to a tremendous1.6-fold performance enhancement. Moreover, the interlayer of CSSQDs could effectively improve the light absorption, the electron transport and extraction, as well as the better interfacial contact between the ETLs and active layers, accordingly resulting in a higher short-circuit current density, fill factor, and a lower series resistance, respectively. Hence, the introduction of CSSQDs interfacial layer could obtain a remarkably increased performance for the inverted PSCs. [ABSTRACT FROM AUTHOR]

Nanoscale, LiNiPO 4 -core and carbon-shell high voltage (>5 V) LiNiPO 4 @C cathode materials have been synthesized using a microwave & solvothermal methodology using different solvents, ethylene glycol, isopropanol, isobutanol and water as the reaction medium. The effects of these solvents on the crystal-quality, morphology and electrochemical qualification of the produced materials have been evaluated in terms of the heating efficiency in the microwave field by using various opto-analytical techniques and electrochemical measurements. The heating characteristics in terms of the absorption of the energy as part of the microwave-material interaction phenomenon is also discussed. X-ray diffraction analyses demonstrate that it is possible to synthesize substantially pure LiNiPO 4 crystal using isopropanol as the reaction medium. High-resolution transmission electron microscopy analysis reveals that this combined methodology can provide core-shell morphology with a 5–6 nm coating thickness. The LiNiPO 4 @C cathode material produced in an isopropanol environment exhibits the best electrochemical properties, achieving a discharge capacity of 157 mAh g −1 at a 0.l C-rate, and shows almost 81% capacity retention at the end of the 80 th cycle. Thus, this paper offers a perspective for solving the difficulties encountered in modifying a high voltage LiNiPO 4 cathode, especially the deficiency in terms of cycle life behavior, and the further benefits are highlighted. [ABSTRACT FROM AUTHOR]

The ageing of lithium-ion battery (LIB) is critical from the application perspective. In this paper, an electrochemical based electrical (ECBE) model is developed to link the model parameters to specific ageing mechanisms. Based on the model parameterization, we report on time resolved degradation processes of LIB during the cycle ageing. The sequence of internal components degradation mechanisms in graphite/lithium cobalt oxide (LCO) coin cells subjected to up to 1000 galvanostatic charge-discharge cycles are revealed. It is found the LIB degradation proceeds according to a series of inter-connected processes, including: i) Solid electrolyte interphase (SEI) formation on the graphite electrode surfaces; ii) LCO phase transformation from active hexagonal to less active spinel phases; iii) Joule heating due to the increased cell resistance resulting in cracking and re-formation of SEI together with surface spallation at the LCO electrode, as well as degradation of the separator; iv) Active Li losses owing to metal plating on the electrodes during overcharge and overdischarge; v) Exfoliation of the graphite anode and the degradation of LCO cathode; and vi) Intergranular contact disconnection within electrodes. These processes contribute to the overall decay in the storage capacity and the LIB terminal voltage differently as shown experimentally. [ABSTRACT FROM AUTHOR]

Aqueous rechargeable batteries (ARBs) based on migration of two types of shuttle ions not only enrich the battery families but also make it more available for ARBs with operation potential higher than 1.2 V. In this paper, we report on electrochemical properties of ARBs in configuration of NaTi 2 (PO 4 ) 3 /C||LiMn 2 O 4 , i.e. NTP/C||LMO. NTP/C was prepared through a simple and scalable co-precipitation post annealing treatment method and featured with hierarchical structure, high specific surface area, and abundant mesopores. The electrochemical properties of individual anode and cathode were examined in 1 mol L −1 Li 2 SO 4 , 1 mol L −1 Na 2 SO 4 , and 0.5 mol L −1 Li 2 SO 4 /0.5 mol L −1 Na 2 SO 4 mixed electrolyte, respectively. It is found that NTP/C exhibits superior operation in 1 mol L −1 Na 2 SO 4 and inferior operation in 1 mol L −1 Li 2 SO 4 while the situation is contrary for LMO. However, NTP/C||LMO full cells with Li + /Na + -mixed electrolyte exhibit enhanced electrochemical performance, presenting an anode-dependant electrochemical behavior. When operating at 1C, NTP/C||LMO with Li + /Na + -mixed electrolyte can deliver a discharge specific capacity ( C dis ) of 104.6 mA h g −1 based on the weight of NTP/C, and a specific energy ( E cell ) of 59.5 W h kg −1 with corresponding specific power of 76.8 W kg −1 based on the total weight of active electrode materials. After 220 cycles at 1C, the C dis and E cell remain 75.7 mA h g −1 and 43.0 W h kg −1 , respectively. [ABSTRACT FROM AUTHOR]

• A two-step carbon coating process is developed to modify high nickel cathode. • Li/Ni cation mixing and adverse phase transition are suppressed by carbon coating. • Dissolution of transition metals is inhibited by carbon coating. • Improved cyclic stability and enhanced rate performance are achieved. High-nickel ternary cathode materials such as LiNi 0.8 Co 0.1 Mn 0.1 O 2 (NCM811) are among the most promising cathode materials due to their high capacity and low cost. However, irreversible phase transition and interfacial side reactions over cycles remain critical concerns. In this paper, a two-step carbon coating process is developed to suppress the adverse phase transition and excessive side reactions at the electrode-electrolyte interface. Sucrose is melted firstly at mild temperature to be coated onto the particle surface, which is converted into carbon in situ at elevated temperature under oxygen atmosphere. Both the cyclic (96.7% capacity retention after 100 cycles at 1 C) and rate performance (130 mAh g−1 at 5 C) of the NCM811 cathode are effectively improved by the carbon coating treatment. [Display omitted] [ABSTRACT FROM AUTHOR]

In the second companion paper on low Pt-loaded gradient cathode, the degradation of Type II cathode with higher Pt loading (60 wt%) near the cathode/membrane interface was studied and compared to a control cathode with uniform Pt loading (40 wt%). All catalyst coated membranes were deposited through reactive spray deposition technology with average Pt particle size of 2 nm and Pt loadings of 0.05 mg cm −2 and 0.1 mg cm −2 on anode and cathode, respectively. The Type II cathode showed improved fuel cell performance at beginning-of-test (BOT) due to higher Pt utilization benefited from high Pt loading close to the membrane. Although the loss of electrochemical surface area for the Type II cathode was ∼80%, similar to that of the control cathode, the end-of-test performance (EOT) was improved by 50–100 mV, which can be attributed to the reduction of Pt loss in the Pt depletion zone (from 80% to 60%) as well as from 30% to 18% for the entire cathode. A comparison between Type I and Type II cathode was made in terms of Pt retention and particle size distribution. Type II cathode turned out to be more effective than Type I cathode as a result of being able to maintain a higher percentage of smaller particles (<5 nm), even though the Pt loss% was a slightly higher than the Type I cathode. Therefore, when evaluating the end-of-test performance, two crucial parameters need to be considered: (1) the retention the Pt particles in the depletion zone within 0 ∼ 2 μm from the cathode/membrane interface and (2) the percentage of small Pt particles in the cathode at EOT. The usual performance indicator, the electrochemical surface area, ceased to be an effective parameter when the Pt/C catalyst has been degraded. [ABSTRACT FROM AUTHOR]

In this paper screen printed electrodes modified with NiO nanoparticles were developed and characterized. NiO nanoparticles were purposely synthesized by a microwave-assisted procedure followed by calcination either at 400 °C or 600 °C and characterized by X-ray diffraction and Scanning Electron Microscopy. Screen printed electrodes were modified by drop casting of either set of NiO nanoparticles dispersed in different solvents, i.e. H 2 O, CH 3 CN, EtOH and DMF-H 2 O and characterized by Cyclic Voltammentry using ferrycianide as electroactive probe. All NiO-SPEs show enhanced performances with respect to the bare electrodes. The largest electroactive area, homogeneity, electron kinetic transfer and smallest peak-to-peak separation is displayed by the screen printed electrodes modified with NiO prepared at 400 °C and dispersed in H 2 O. Thus this electrode was probed for the detection of benzoquinone, epinephrine and norepinephrine, demonstrating an enhancement of the electrochemical activity and a better separation of the reduction peaks compared to the bare electrodes. [ABSTRACT FROM AUTHOR]

This paper presents a model to theoretically study the key poisoning-related concepts including Dimensionless Cell Voltage (DCV), nonlinear algorithm of poisoning progress, smooth and accelerated poisoning progress regions, intensification point, and the rate of poisoning progress. A 3-D multicomponent transient solver, based on a comprehensive mathematical model including reaction kinetics, governing equations, boundary conditions and constitutive relations, in the open source code package, OpenFOAM, has been developed that has the capability of simulating anode side of PEM fuel cell in poisoning condition. This study suggests an optimum parametric voltage range for choosing purge characteristics of fuel cells operated in dead ended mode as well as an optimum range of efficient oxygen bleeding that must be used to cure or prevent CO poisoning. Studying the effects of key operating conditions on the poisoning progress algorithm showed that increasing the CO concentration, current density and operating temperature, and also lowering the catalyst Pt loading can all reduce the poisoning period and speed up its progress rate. The results also showed that poisoning progress follows a nonlinear algorithm. Based on the Response Surface Method (RSM), a series of parametric correlations were extracted to predict the poisoning progress algorithm according to above-mentioned operating conditions. [ABSTRACT FROM AUTHOR]

The unique physical and chemical properties of conventional room temperature ionic liquids (RTILs) render them highly deployable materials in electrochemical devices performing functions such as solvent-free electrolytes in capacitors, batteries and sensors. However, these non-faradaic applications can be complimented by incorporating faradaic redox functionality into the ionic liquid structure which facilitates access to a large array of new electrochemical applications such as dye sensitised solar cells, redox batteries, hydrid capacitors and selective amperometric sensor applications which are all reliant on heterogeneous or homogenous electron-transfer processes. This paper presents and discuses some examples of redox active ionic liquids base on the ferri-/ferro- functionality. These functional electro-materials which are already known [Ref. [18]] exhibit simple reversible one-electron electrochemistry at very negative potentials (by at least −1 V relative to aqueous systems) in anhydrous media. Glass transition temperatures lower than −50 °C were also observed along with an overall thermal stability up to at least 400 °C under dry N 2 atmosphere conditions. Opportunities and challenges for these types of electro-materials are discussed. [ABSTRACT FROM AUTHOR]

Long term ageing experimental results show that degradation resulting from coupled DC and AC current waveforms lead to additional degradation of lithium-ion batteries above that experienced through pure DC cycling. More profoundly, such experiments show a dependency of battery degradation on the frequency of AC perturbation. This paper addresses the underlying causality of this frequency dependent degradation. Cell autopsy techniques, namely X-ray photoelectron spectroscopy (XPS) of the negative electrode surface film, show growth of surface film components with the superimposition of an AC waveform. XPS results show that high frequency AC perturbations lead to the increased formation of a passivating film. In order to determine the cause of this increased film formation, a heterogeneous electrochemical model for the LiNiCoAlO 2 /C 6 lithium ion battery coupled with governing equations for the electrical double-layer and solid electrolyte interface film growth is developed. Simulation results suggest that the increased growth of surface film is attributed to frequency dependent heat generation. This is due to ion kinetics in the double layer which are governed by the Poisson-Boltzmann equation. Additional thermal and reference cell relaxation experiments are undertaken that further corroborates the conclusion that heat generation within the battery is a function of the AC excitation frequency through resistive dissipation and the entropy of the cell reaction. [ABSTRACT FROM AUTHOR]

1 The interactions within particles of different sizes are quantitatively analyzed. 2 The interparticle lithium diffusion and the intraparticle lithium diffusion are competitive. 3 The rest period during the CC CV protocol can be reduced for a higher cycle efficiency. 4 An appropriate kinetic matching between cathode and anode will reduce the lithium plating risk. In order to get a super comprehensive performance, electrodes in high energy density batteries always consist of particles with different features. Thus, a deep insight into the interaction between particles can help to further improve the electrode performance. In this paper, an extended pseudo-2-dimension (P2D) model based on a 60 Ah high-energy-density (HED) Li-ion pouch cell (≥280 Wh kg−1) with Si-based anode/Ni-rich cathode couple is established and the internal micro characteristics within electrodes are investigated. A competitive relationship in the direction between particle radial and electrode thickness is observed, and therefore electrodes composed of more large particles have a higher utilization at aluminum (Al) foil current collector. There is a big difference in the average state-of-charge (SOC) between the two particles. Fortunately, the huge difference between particles can be balanced out during the constant voltage process or rest period. According to the model, electrodes with big particles besides the separator and small particles besides the current collector may exhibit the best overall performance and an appropriate kinetic matching between cathode and anode is more beneficial to high-rate charging, rather than a superior positive electrode alone, taking the lithium plating risk into account. [Display omitted] [ABSTRACT FROM AUTHOR]

A flexible solid-state supercapacitor based on iron sulfide (FeS 2 ) nanospheres supported on carbon-paper is fabricated, which exhibits excellent electrochemical performance such as, high capacitance of 484 F g −1 at a scan rate of 5 m Vs −1 , good rate capability, and excellent cycling stability (95.7% after 5000 cycles). The supercapacitor achieves high energy density of 44 Wh kg −1 at power density of 175 W kg −1 with high coulombic efficiency (97%). Three charged supercapacitors connected in series can power 12 green-color light-emitting-diodes (LED, 3.0 V, 20 mA) for 5.5 minutes. To understand the detailed electrochemistry, we have carried out both experimental and theoretical investigations. The pseudocapacitive characteristics of the FeS 2 nanospheres are systematically investigated by a single electrode in aqueous electrolyte. According to our structural analysis, the FeS 2 nanospheres have orthorhombic structure, where Fe atoms are surrounded by 6 S atoms to form a FeS 6 octahedron. These octahedrons are connected to form a network structure, which provide tunnels (2.55 × 4.77 Å). With all the evidence, we believe that the FeS 2 nanospheres could be a promising material for supercapacitor electrodes. [ABSTRACT FROM AUTHOR]

This paper develops a computational model and applies it to investigate the performance of a rechargeable battery that is comprised of a molten-sodium anode, a NASICON sodium-ion-conducting separator membrane, and a iodine-based cathode. The cathode compartment is comprised of a porous-carbon felt and an aqueous catholyte that supports an iodine redox process. The battery chemistry can be represented globally as 2Na + + 2I − ⇌ 2Na + I 2 . The ion transport is represented in terms of a Nernst–Planck formulation that includes four mobile species within the catholyte, Na + , I − , I 3 − , and I 2 . The charge transfer chemistry is modeled using a Butler–Volmer formulation. The model considers solubility limits and the potential precipitation of NaI and I 2 . Parameter studies investigate the influences of charge and discharge rates, total elemental iodine loading, and effective conductivity of the carbon-felt cathode. [ABSTRACT FROM AUTHOR]

A newly designed conducting polymer (poly(N(-pyridin-4-ylmethyl)aniline)), POB), having a polyaniline backbone and pyridine pendant groups, has been electrosynthesized and studied in this paper. The characterization predominantly focuses on the possible application of the polymer-modified electrode in electrochemical fuel generation (H 2 production and CO 2 reduction). POB can be regarded as a pyridine-based electrocatalyst (mediator) immobilized on an electrode surface as part of a conjugated polymer, as confirmed by the appearance of a redox wave centered at E = −0.53 V (vs. Ag/AgCl) on the cyclic voltammogram of POB. The effects of experimental conditions (pH of the electrolyte, layer thickness, and material of the substrate electrode) on the immobilized pyridine-ring electrochemistry have been carefully analyzed, to understand the underlying factors governing the electrochemical behavior of this new functional material. Finally, the electrocatalytic behavior of POB was tested towards CO 2 reduction and H 2 evolution. [ABSTRACT FROM AUTHOR]

This paper is devoted to the study of electrochemical behaviour of insecticide chlorpyrifos with proved endocrine disruptor properties and to the finding of the optimum conditions for its determination using differential pulse voltammetry (DPV) at a mercury meniscus modified silver solid amalgam electrode (m-AgSAE). It was confirmed that the electrochemical reaction is based on the reduction of H + ions catalysed by chlorpyrifos adsorbed on the surface of the m-AgSAE. Two variants of the m-AgSAE were tested: i) freshly prepared m-AgSAE for each set of measurements with a classical previously published electrochemical activation (5 min at −2.2 V in 0.2 mol.L −1 KCl under stirring and in the presence of oxygen) for which the optimal base electrolyte was found to be the acidic part of the Britton-Robinson (BR) buffer (pH 1.82) containing 15% of methanol and ii) freshly prepared m-AgSAE for each set of measurements with a newly developed simplified electrochemical activation (10 s at −2.2 V in the stirred base electrolyte alone in the presence of oxygen) for which the optimal base electrolyte was found to be the acidic part of the BR buffer (pH 1.82) containing 30% of methanol. [ABSTRACT FROM AUTHOR]

The mediated electrochemical reduction of NAD(P)+ in aerated solution was investigated and exploited for NAD(P)H regeneration in view of biosensing application. Oxygen was locally removed from the electrode surface with an electrochemical oxygen filter made of platinum grids positioned close to the oxygen sensitive reactions. The working electrode was a bucky paper functionalized with [Cp∗Rh(bpy)Cl]+ by diazonium electrografting. The local oxygen removal was first evaluated, before to be applied to deoxygenation for NAD+ and NADP+ reduction. A porous silica gel layer encapsulating d -sorbitol dehydrogenase was finally deposited on the top of the modified bucky paper and the resulting bioelectrode was found sensitive to the presence of d -fructose. [ABSTRACT FROM AUTHOR]

Anodic oxide and hydroxide films on metals are very important for corrosion protection and they determine the electrochemical properties of electrode surfaces. For a better understanding of the leading corrosion mechanisms the chemical composition as well as the structure and electronic properties of passive layers are of decisive importance. They have been investigated with numerous ex situ and in situ methods. In this review special attention is given in a first part to the application of X-ray Photoelectron Spectroscopy (XPS), Ion Scattering Spectroscopy (ISS) and Rutherford Backscattering (RBS) as ex situ methods, which provide detailed information on the chemical composition and the multilayer structure of these films. The second part concentrates on the application of Scanning Tunneling Microscopy (STM) to obtain information on the atomic structure of these layers and their changes with environmental parameters. Passive layers are usually complicated multilayer structures. Their protecting properties are determined by the chemical characteristics of the metals and their anodic oxides as well as the environmental factors as the potential and the composition of the contacting electrolyte. The investigation of some metals and alloys like Cu, Fe, Co, Al/Cu and Fe/Cr are presented in detail to give insight to the application of electrochemical and surface analytical methods. It is the aim of this review to show, that one has to apply many methods in combination to understand the mechanisms of the leading corrosion processes and the nature of the passive behavior. References to more detailed reviews and original papers are given. [ABSTRACT FROM AUTHOR]

Spinel Li 4 Ti 5 O 12 (LTO) has been intensively investigated as promising anode material for large-scale stationary electrochemical storage of energy produced from renewable sources due to its remarkable structural stability and excellent safety. In this paper, nanoparticles-constructed LTO with extra surface lithium storage capability is successfully prepared in air at 600 °C via employing TiOSO 4 ·2H 2 O as Ti source. The newly prepared nanoparticles-constructed LTO displays enhanced electrochemical performances, demonstrating ultrahigh reversible capacity of 173 mAh g −1 at 0.5C and superior rate performance of more than 145 mAh g −1 at 30C between 1.0 and 2.5 V vs. Li + /Li. The influences of specific surface area and crystallinity on the extra surface lithium storage capability of the sintered samples for LIBs are investigated in detail in terms of reversible capacity, cyclability and rate capability. Our results reveal that not only specific surface area but also crystallinity and pored structure are vital for reducing electrode polarization and achieving extra surface lithium storage of LTO. We anticipate that the uniquely extra surface lithium storage reaction of LTO will get more attentions in the near future. [ABSTRACT FROM AUTHOR]

We here report a lanthanum ferrite-based perovskite anode La 0.9 Ca 0.1 Fe 1-x Nb x O 3-δ (LCFNbx, x = 0, 0.05, 0.1 and 0.2) for solid oxide fuel cells (SOFCs) with intriguing stability and electrochemical performance. The powders were prepared by citric acid-nitrate method. The LCFNbx/ScSZ ((Sc 2 O 3 ) 0.1 (CeO 2 ) 0.01 (ZrO 2 ) 0.89 ) composite anodes were constructed by infiltrating the corresponding metal nitrate solution into the ScSZ scaffold followed by heat treatment. X-ray diffractometer results indicated that Nb doping in B site can stabilize the material in the reducing atmospheres up to 800 °C. The chemical stability of LCFNb 0.1 is attributed to the constrained valence stability of Fe by the Nb introduction in highly charged state. The maximum power densities of the cell with LCFNb 0.1 /ScSZ composite anode were 467.1 and 375.8 mW/cm 2 in H 2 and CO at 750 °C, respectively. The area specific resistances of the cell at open circuit voltage were 0.75 and 2.30 Ωcm 2 , respectively. Scanning electron microscopy results showed that the LCFNb 0.1 layer was porous and well adhered to the ScSZ scaffold, which facilitated the electrochemical processes in H 2 and CO. The obtained results in this paper indicate that the LCFNb 0.1 /ScSZ is a promising composite anode for the SOFCs with both high stability and high electrochemical performance in H 2 and CO. [ABSTRACT FROM AUTHOR]

In this paper, novel ε-MnO 2 microspheres with uniform flaky texture were synthesized by a precursor conversion method. Basing on this material, a novel ε-MnO 2 microspheres/chitosan/GCE (glassy carbon electrode) electrochemical sensor prepared by a simple physical deposit method was developed for the ultrasensitive determination of Ponceau 4R. The proposed electrochemical sensor exhibits remarkable electrocatalytic activity towards Ponceau 4R, suggesting a potentially detailed reaction mechanism catalyzed by ε-MnO 2 and demonstrating a wide linear detection range from 0.005 to 1000 μmol dm −3 and a low detection limit of 0.1 nmol dm −3 (S/N = 3) for Ponceau 4R. The sensor also shows promising selectivity, stability and reproducibility and finally, is applied to determine Ponceau 4R in real samples, giving satisfactory results. [ABSTRACT FROM AUTHOR]

Electrochemical micro-cell systems based on the use of glass micro-capillaries enable to perform standard electrochemical measurements on areas with dimension in the micro- or submicrometer range. The base principle is the miniaturization of the working electrode, which is obtained using a micro-capillary to position the electrolyte on the sample surface. This technique has been extensively employed for the investigation of localized corrosion in passive surfaces like steels and aluminium alloys. This paper presents examples of the study of localized corrosion and its inhibition in aluminium alloys by means of the electrochemical micro-cell. These are discussed trying to highlight the major advantages and the critical aspects related to the use of the technique. Moreover, the combined use of the electrochemical micro-cell with other electrochemical and surface analysis techniques highlights that the micro-cell technique is a very powerful method for the investigation of corrosion phenomena. [ABSTRACT FROM AUTHOR]

Mg–O 2 batteries appear to be a promising alternative to Li-O 2 system due to the high abundancy and volumetric energy density of Mg. Although much effort has been put into research on Li-O 2 batteries, little is known about the oxygen reduction and evolution in Mg 2+ -containing aprotic electrolytes. In this paper, we present a detailed analysis of the ORR in Mg 2+ -containing DMSO using RRDE and DEMS-techniques and derive a more general reaction mechanism of ORR in aprotic electrolytes using the results for Li + , Na + and K + -containing DMSO. O 2 first reacts via an initial adsorption step to superoxide which, in the presence of Mg 2+ , is subsequently reduced to peroxide as the main reaction product. However, this product undergoes further reactions leading to a deactivation of the electrode. Regarding the reversibility, unfortunately no OER was observed and reactivation of the electrode proved difficult. [ABSTRACT FROM AUTHOR]

Epigenetic modifications have been associated by many studies with several types of diseases and metabolic dysfunctions. Specifically, N7-methyl modification of guanine (7-mG) is well established to be used as a biomarker for the detection and determination of DNA methylation. The use of an electrochemical sensor has the potential to provide a simpler and more economic sensing methodology for the determination of 7-mG compared to traditionally utilised laboratory based approaches. In this paper we demonstrate the feasibility of an electrochemical sensor which could potentially be easily applied towards the determination of 7-mG within biological samples, such as human urine. A practical electrochemical configuration was employed consisting of a boron-doped diamond electrode (BDD) as the working electrode and a screen-printed graphite electrode (SPE) providing the counter electrode and the reference electrode. With this new protocol, the electrochemical behaviour of 7-mG has been investigated via cyclic voltammetry (CV) and square wave voltammetry (SWV) using a BDD electrode with a simplified electrochemical set-up. The electrochemical behaviour of 7-mG within acetate buffer solutions at a BDD electrode has been compared and contrasted to a glassy carbon electrode with the following parameters studied: voltammetric scan rate, solution pH, 7-mG concentration and electrode surface pretreatment. The oxidative mechanism elucidation has been performed at controlled potential and such results have provided the dimer formation as the major product. The simultaneous electroanalytical identification of 7-mG together with the presence of guanine, adenine and 8-oxoguanine has been investigated under the optimum experimental conditions. Furthermore, the feasibility of using a BDD electrode for the detection of 7-mG is explored in a human urine sample. [ABSTRACT FROM AUTHOR]

In this paper, we report the use of Zn 0.76 Co 0.24 S/CoS 2 nanowires array on Ti mesh (Zn-Co-S/TM) topotactically derived from ZnCo 2 O 4 nanowires array precursor as a durable and efficient bifunctional hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) catalyst in strongly alkaline media. This Zn-Co-S/TM electrode drives 20 mA cm −2 at 238 mV HER overpotential and 20 mA cm −2 at 330 mV OER overpotential. The corresponding two-electrode alkaline water-splitting system achieves 10 mA cm −2 at a cell voltage of 1.66 V. [ABSTRACT FROM AUTHOR]

Electrochemical techniques, such as electrochemical impedance spectroscopy (EIS), are widely used for corrosion studies. However, their applicability to studies on metallic cultural heritage has been less spread due to the practical difficulties of performing measurements in-situ on sculptures or monuments. One interesting approach to this application is the use of gel polymer electrolytes (GP-E) to overcome the difficulties of handling liquid electrolytes on irregular leaning surfaces. In this paper, the behavior of an agar gelled electrolyte with a portable cell is evaluated for EIS measurements over three types of bronze coupons, and compared with a traditional liquid cell. The influence of the addition of agar in the reproducibility and repeatability of measurements is assessed, as well as the possible interaction of agar with the corrosion process. Results show that, although agar slightly accelerates the anodic process, it does not significantly affect the cathodic reaction and does not introduce new reactions in the corrosion mechanism. It is demonstrated that the GP-E allows obtaining reproducible and good quality EIS spectra, comparable to the liquid cell. Hence, it can be used for comparative in-situ measurements, being a very valuable tool for the evaluation of patina and coatings on metal cultural heritage. [ABSTRACT FROM AUTHOR]

Free-standing, flexible, paper-like Fe 2 O 3 /graphene/carbon nanotubes (Fe 2 O 3 /GCNTs) ternary hybrid film with a three-dimensional hierarchical structure is synthesized through a simple filtration and a subsequent reduction process. The Fe 2 O 3 particles are densely anchored onto the GCNTs conducting network, which serves as an ideal host for fast and efficient lithium storage. The layered GCNTs network not only withstands the huge stresses caused by Fe 2 O 3 expansion/extraction but prevents the agglomeration of Fe 2 O 3 upon continuous charging/discharging. The as-synthesized Fe 2 O 3 /GCNTs hybrid film is directly used as an anode for both half and full lithium-ion cells. Electrochemical measurement results indicate a high reversible capacity and a good rate capability can be realized on the hybrid when tested in half cell system. Furthermore, the prepared anode also shows favorable operation in full cell system comprising LiCoO 2 cathode. These superior electrochemical performances of the hybrid film can be ascribed to the unique micro-structure, surface properties, and the strong synergistic effects among the individual component. [ABSTRACT FROM AUTHOR]