Electrochemistry

The electrochemical reduction of Ta 2 O 5 in a LiCl-Li 2 O molten salt system has been carried out in an electrolytic cell with an integrated cathode assembly. During the electrochemical run, Ta 2 O 5 reacts chemically with Li 2 O to form LiTaO 3 . The chronopotentiometry method was used to prepare the metallic tantalum from Ta 2 O 5 . The electrolysis of Li 2 O and the reduction of Ta 2 O 5 and/or LiTaO 3 take place simultaneously at the cathode part of an electrolysis cell. The recycle of Li 2 O by an O 2-diffusion occurs in the cell. The results suggest that the metallic tantalum is prepared successfully by an electrochemical reduction in the LiCl-Li 2 O molten salt.

Yeni, suda çözünen 2(3),9(10),16(17),23(24)-tetrakis [4-(1-naftoksi-4-sulfonik asit sodyum)] kobalt(II)ftalosiyanin, NhtCoPc (Nht burada 1-naftoksi-4-sulfonik asit sodyum tuzu), sentezlendi, elementel analiz yöntemi, spektroskopik yöntemlerle (IR ve UV–vis) karakterize edilerek ve elektro-kimyasal, spektroelektrokimyasal ve moleküler oksijenin indirgenmesine yönelik elektro-katalitik davranışları detaylı bir şekilde incelendi. Kompleksleşme reaksiyonu metanol ortamında 2(3),9(10),16(17),23(24)- tetrakis [4-(1-naftoksi-4-sulfonik asit sodyum)] ftalosiyanin, NhtH2Pc’nin UV-vis spektrum değişikliklerine göre takip edildi. Q bandının maksimum şiddette olduğu anda reaksiyon tamamlandı. Elektrokimyasal çalışmalardan şu sonuçlar çıkarılmıştır: DMSO çözeltisinde kobalt(II) kompleksi anodik dalgaya karşılık gelen bir elektronlu iki tersinir indirgenme reaksiyonu ve bir tersinir olmayan yükseltgenme re...

Pc'nin UV-vis spektrum değişikliklerine göre takip edildi. Q bandının maksimum şiddette olduğu anda reaksiyon tamamlandı. Elektrokimyasal çalışmalardan şu sonuçlar çıkarılmıştır: DMSO çözeltisinde kobalt(II) kompleksi anodik dalgaya karşılık gelen bir elektronlu iki tersinir indirgenme reaksiyonu ve bir tersinir olmayan yükseltgenme reaksiyonu sergilemiştir. Gerçekleşen indirgenme reaksiyonları ve yükseltgenme reaksiyonu, Co(1+)Pc( Pt/PAni-NhtCoPc elektrot hazırlandı. Modifiye edilmiş elektrot SEM (elektron mikroskopu ile) karakterize edildi. NhtCoPc'ninpolimerizas-yon ortamına ilavesi ile elde edilen filmin morfolojisi önemli ölçüde değiştiği ve oluşan PAni-NhtCoPc filmin oksijen indirgenmesine yönelik redoks aktivitesinin yalnız platin ya da Pt/PAni elektrodlara kıyasla aynı deney koşullarında arttığı görüldü.

Preparação e caracterização de nanocompósitos de nanopartículas metálicas e proteínas e suas aplicações em biossensores 2010 -1 -Agradecimentos Nenhum projecto é possível sem o apoio, incentivo e colaboração de todos aqueles que nos estão mais próximos. Quero deixar o meu agradecimento a todos os que tornaram possível a realização deste projecto. Quero deixar o meu agradecimento especial ao Prof. Doutor Hugo Águas, que me orientou com paciência e dedicação durante o tempo que durou este projecto. Quero agradecer também ao Doutor João Cortez, que sem a sua paciência, dedicação e orientação, não teria sido possível a realização deste trabalho. Quero agradecer a todos os investigadores do Cenimat, em especial à amiga e colega Diana Gaspar, que me apoiou nas longas horas de cortar substratos e fazer deposições, na câmara limpa. Agradeço aos meus colegas de Mestrado e de laboratório, eles sabem o quanto me ajudaram a levar este projecto para a frente. Quero agradecer ao Prof. Doutor Carlos Dias, coordenador do Mestrado, por toda a paciência e ajuda que deu a todos os alunos deste Mestrado. Quero agradecer ao Prof. Doutor Rodrigo Martins e à Prof.ª Doutora Elvira Fortunato, por terem possibilitado o acesso ao Mestrado de Microelectrónica e Nanotecnologia e por todo o apoio dado e conhecimento transmitido, ao longo do meu percurso académico, tanto na Licenciatura como no Mestrado. Agradeço à Inês Osório, colega do 603, pelo apoio dado nas horas de desespero com a Química e nas idas à máquina do café. Agradeço também ao Prof. Doutor Ricardo Franco por me ter integrado tão bem no laboratório e por todo o apoio dado. Quero agradecer à Inês Gomes, também colega do 603, por me ajudar a perceber alguns conceitos de Química e quero agradecer à Mestre Leonor Soares, pela síntese e funcionalização das AuNP e ao Investigador Peter Eaton, pelos ensaios de AFM, ambos do REQUIMTE/Faculdade de Ciências da Universidade do Porto. Agradeço aos meus amigos mais próximos. E por último, mas não com menos importância, quero agradecer às pessoas mais importantes da minha vida, a minha família, a minha mãe e irmã, que tanta paciência tiveram comigo ao longo desta jornada. E dedico este trabalho ao meu pai, porque se não fosse por ele não estaria a acabar este Mestrado. Preparação e caracterização de nanocompósitos de nanopartículas metálicas e proteínas e suas aplicações em biossensores 2010 Preparação e caracterização de nanocompósitos de nanopartículas metálicas e proteínas e suas aplicações em biossensores 2010 -3 -

Silicon (Si) nanowires (NWs) grown on stainless-steel substrates by Cu-catalysed Chemical Vapour Deposition (CVD) have been prepared to be used as anodes in lithium-ion batteries. The use of NWs can overcome the problems related to the Si volume changes occurring during lithium alloying by reducing stress relaxation and preventing material fragmentation. Moreover, since the SiNWs are grown directly on the substrate, which also acts as a current collector, an excellent electrical contact is generated between the two materials without the necessity to use additional binders or conducting additives. The electrochemical performance of the SiNWs was tested in cells using lithium metal as the anode. A large irreversible capacity was observed during the first cycle and, to a lesser extent, during the second cycle. All the subsequent cycles showed good reversibility even if the coulombic efficiency did not exceed 95%, suggesting the formation of an unstable SEI film and a continuous decomposition of the electrolyte on the silicon surface. The absence of a stable SEI film was assumed responsible for a linear capacity fade observed upon cycling. On the other hand, the electrochemical characterization performed at different values of the charging current showed that SiNWs possess an exceptionally high rate capability.

This paper describes a method for the preparation of composite cathodes for lithium ion-batteries by using poly vinyl acetate (PVAc) as a binder. PVAc is a non-fluorinated water dispersible polymer commonly used in a large number of industrial applications. The main advantages for using of this polymer are related to its low cost and negligible toxicity. Furthermore, since the PVAc is water processable, its use allows to replace the organic solvent, employed to dissolve the fluorinated polymer normally used as a binder in lithium battery technology, with water. In such a way it is possible to decrease the hazardousness of the preparation process as well as the production costs of the electrodes. In the paper the preparation, characterization and electrochemical performance of a LiFePO 4 electrode based on PVAc as the binder is described. Furthermore, to assess the effect of the PVAc binder on the electrode properties, its performance is compared to that of a conventional electrode employing PVdF-HFP as a binder. 2014 Published by Elsevier Ltd.

In this study it was aimed to enhance cycling performance of silicon lithium ion battery anodes via producing flexible Silicon/Graphene/MWCNT composite structures. The volumetric expansions, which are the primary obstacle that hinders the practical usage of silicon anodes, were tried to suppress using flexible graphene/MWCNT paper substrates. Moreover to achieve lightweight and high electrical conductive anodes, the advantage of graphene was aimed to be exploited. Silicon/graphene/MWCNT flexible composite anodes were produced via radio frequency (RF) magnetron sputtering technique. Graphene/MWCNT papers were produced with vacuum filtration technique as substrate for sputtering process. At coating process of papers constant sputtering power was applied. Phase analysis was conducted with X-ray diffraction (XRD) technique and Raman spectroscopy. Field emission scanning electron microscopy (FESEM). Cyclic voltammetry (CV) tests were carried out to reveal reversible reactions between silicon and lithium. Galvanostatic charge/discharge technique was employed to determine the cyclic performance of anodes. Electrochemical impedance spectroscopy technique was used to understand the relation between cyclic performance and internal resistance of cells. Results showed that improvement on cyclic performance of silicon anodes was achieved with novel composite silicon/graphene/MWCNT composite anode structures.

Ethoxy ester functionalized imidazolium and bis(tri fluoromethanesulfonyl)imide based ionic liquids (ILs) are synthesized and considered as electrolyte for lithium ion batteries. The series of ethoxy ester functionalized ionic liquids were chosen with increase in ethoxy unit from one to three, followed by polymeric units. These ionic liquids provide both ester and ethoxy groups as interaction sites for Li+ ions enhancing the Li+ ion transportation, resulting in ionic conductivity of 10−3 Scm−1 at 25 °C, which is of 103 factor higher than ethoxy containing polyethylene oxide solid polymer electrolyte. It's noteworthy that the conductivity increases as ethoxy units are increased from one to three units, followed by a decrease for the polymeric ethoxy unit. Electrochemical stability window of these ionic liquids improves as the ethoxy groups are added to imidazolium cation. The Li/LiFePO4 cell fabricated with [ME3AMIm][TFSI] electrolyte shows good initial discharge capacity of 98.5...

Graphene hybrid aerogels have attracted attention as electrode materials because of their unique porous architectures. However, their electrochemical performance is limited by the intrinsic hydrophobicity and the ease of aggregation of graphene nanosheets. We demonstrate a unique methodology to produce graphene hybrid aerogels through assembly of graphene nanosheets, nanometer-scale ferroferric oxide (Fe 3 O 4 ), and hydrophilic poly(vinyl alcohol) (PVA) into three-dimensional hierarchical macrostructures. Electrochemical performance measurements exhibit a significant improvement in the specific capacitance of this ternary hybrid aerogel with remarkable cycling stability. Specifically, the specific capacitance is nearly 6.6 times higher than that of the neat graphene aerogel, and a cycling capacitance retention rate of 99% was achieved after 2000 cycles at a high current density of 0.5 A g 21 . Electrochemical impedance spectroscopy measurements demonstrate a lower resistance in the Fe 3 O 4 /graphene/PVA aerogel electrode compared with that of both neat graphene and Fe 3 O 4 /graphene aerogel electrodes. The obtained graphene hybrid aerogels with outstanding cycling performance and high energy density are very promising as electrode materials for supercapacitors. V

The electrochemical regeneration of Ce(IV) for mediated electrochemical oxidation in sulfuric acid media was investigated in an electrolytic membrane reactor. A simple kinetic model was developed to analyze and simulate the regeneration of Ce(IV) in the electrolysis process. The model was based on the Faraday's law and the mass balance of components in the reactor. The key operating conditions of the initial electrolyte concentration and the regeneration time were analyzed. It was found that the simulating model agreed well with the experimental data for regeneration of Ce(IV). Experimental results showed that Ce(SO 4 ) -2 is the active species. The decomposition of surface complex of Ce(IV) at the anode surface is the rate determining step. Constant-current electrolysis shows that the high proton and Ce(III) concentrations are electrochemically favorable for the regeneration of Ce(IV). The current efficiency for regeneration of Ce(IV) decrease obviously with the increase of SO 4 2-concentration from 0.8 to 2.4 mol/L.

h i g h l i g h t s g r a p h i c a l a b s t r a c t Semiconducting Mg(Zn)Al(Ga)eLDH/ ITO thin films prepared by solegel. LDH thin films show a turbostratic morphology made up of porous flakes. Electrochemical treatments change the flaky structure into a nanoparticle array.

In mammalian cells, the DNA damage-related histone H2A variant H2A.X is characterized by a C-terminal tyrosyl residue, Tyr-142, which is phosphorylated by an atypical kinase, WSTF. The phosphorylation status of Tyr-142 in H2A.X has been shown to be an important regulator of the DNA damage response by controlling the formation of ␥H2A.X foci, which are platforms for recruiting molecules involved in DNA damage repair and signaling. In this work, we present evidence to support the identification of the Eyes Absent (EYA) phosphatases, protein-tyrosine phosphatases of the haloacid dehalogenase superfamily, as being responsible for dephosphorylating the C-terminal tyrosyl residue of histone H2A.X. We demonstrate that EYA2 and EYA3 displayed specificity for Tyr-142 of H2A.X in assays in vitro. Suppression of eya3 by RNA interference resulted in elevated basal phosphorylation and inhibited DNA damage-induced dephosphorylation of Tyr-142 of H2A.X in vivo. This study provides the first indication of a physiological substrate for the EYA phosphatases and suggests a novel role for these enzymes in regulation of the DNA damage response.

Owing to their high redox potential and availability of numerous diffusion channels in metal-organic frameworks, Prussian blue analogs (PBAs) are attractive for metal ion storage applications. Recently, vanadium ferrocyanides (VFCN) have received a great deal of attention for application in sodium-ion batteries, as they demonstrate a stable capacity with high redox potential of ~3.3 V vs. Na/Na + . Nevertheless, there have been no reports on the application of VFCN in lithium-ion batteries (LIBs). In this work, a facile synthesis of VFCN was performed using a simple solvothermal method under ambient air conditions through the redox reaction of VCl 3 with K 3 [Fe(CN) 6 ]. VFCN exhibited a high redox potential of ~3.7 V vs. Li/Li + and a reversible capacity of ~50 mAh g -1 . The differential capacity plots revealed changes in the electrochemical properties of VFCN after 50 cycles, in which the low spin of Fe ions was partially converted to high spin. Ex situ X-ray diffraction measurements confirmed the unchanged VFCN structure during cycling. This demonstrated the high structural stability of VFCN. The low cost of precursors, simplicity of the process, high stability, and reversibility of VFCN suggest that it can be a candidate for large-scale production of cathode materials for LIBs.

SnO 2 nanoparticles (NPs) have been used as reversible high-capacity anode materials in lithium-ion batteries, with reversible capacities reaching 740 mAh•g -1 . However, large SnO 2 NPs do not perform well in charge-discharge cycling. In this work, we report the incorporation of MoS 2 nanosheet (NS) layers with SnO 2 NPs. SnO 2 NPs of ~5 nm in diameter synthesized by a facile hydrothermal precipitation method. Meanwhile, MoS 2 NSs of a few hundreds of nanometers to a few micrometers in lateral size were produced by top-down chemical exfoliation. The self-assembly of the MoS 2 NS layer on the gas-liquid interface was first demonstrated to achieve up to 80% coverage of the SnO 2 NP anode surface. The electrochemical properties of the pure SnO 2 NPs and MoS 2 -covered SnO 2 NP anodes were investigated. The results showed that the SnO 2 electrode with a single-layer MoS 2 NS film exhibited better electrochemical performance than the pure SnO 2 anode in lithium storage applications.

It has been shown that, for the case of one-step reactions of arbitrary order, the relationship between the average current density and the limiting current density on a working electrode mounted on the inner radius of an annular flow channel of arbitrary length obeys, with great accuracy, the same relations as does a reaction on a uniformly accessible surface. This allows us to combine the advantages of non-uniformly accessible surfaces (high sensitivity, and no need to use rotating contacts) with the advantages of uniformly accessible surface systems (simple treatment of experimental data). This feature can be very important when investigating systems at high temperatures and pressures, where RDEs are difficult to employ. Using this approach, and by employing previously measured polarization data, the kinetic parameters (exchange current density and anodic transfer coefficient) for the oxidation of hydrogen on platinized nickel in 0.1 M NaOH + 0.7 × 10 -3 m H 2 at temperatures between 25 • C and 300 • C have been derived. The anodic transfer coefficient is found to be almost temperature independent with a value of 0.43. The exchange current density displays Arrhenius behavior with temperature, increasing from 1.9 × 10 -4 A cm -2 at 25 • C to 3.9 × 10 -3 A cm -2 at 300 • C.

Since their discovery, MXenes have conferred various intriguing features because of their distinctive structures. Focus has been placed on using MXenes in electrochemical energy storage including a supercapacitor showing significant and promising development. However, like other 2D materials, MXene layers unavoidably experience stacking agglomeration because of its great van der Waals forces, which causes a significant loss of electrochemically active sites. With the help of MoS 2 , a better MXene-based electrodecan is planned to fabricate supercapacitors with the remarkable electrochemical performance. The synthesis of MXene/MoS 2 and the ground effects of supercapacitors are currently being analysed by many researchers internationally. The performance of commercial supercapacitors might be improved via electrode architecture. This analysis will support the design of MXene and MoS 2 hybrid electrodes for highly effective supercapacitors. Improved electrode capacitance, voltage window and energy density are discussed in this literature study. With a focus on the most recent electrochemical performance of both MXene and MoS 2 -based electrodes and devices, this review summarises recent developments in materials synthesis and its characterisation. It also helps to identify the difficulties and fresh possibilities MXenes MoS 2 and its hybrid heterostructure in this developing field of energy storage. Future choices for constructing supercapacitors will benefit from this review. This review examines the newest developments in MXene/MoS 2 supercapacitors, primarily focusing on compiling literature from 2017 through 2022. This review also presents an overview of the design (structures), recent developments, and challenges of the emerging electrode materials, with thoughts on how well such materials function electrochemically in supercapacitors.

Discharge performances of Ti 45 Zr 38-x Ni 17+x (0 ≤ x ≤ 8) ribbons produced by rapid-quenching were measured by a three-electrode cell at room temperature, and the effect of substitution of Ni for Zr was investigated. All the ribbons after rapid-quenching were mostly the icosahedral (i) quasicrystal phase with a negligible amount of C14 Laves phase (hcp). The discharge capacity increased with increasing amount of Ni substituted for Zr. The maximum discharge capacity achieved was about 90 mAh/g from (Ti 45 Zr 30 Ni 25 ) ribbon after substitution of Ni for Zr. The discharge performance was almost stable against the charge/discharge cycle (until 15 cycles) for all the ribbons, and the i-phase structure was also stable even after the 15th charge/discharge cycle. No metal hydride formation was observed.

Heterostructured ZnSe-ZnTe quantum wires are grown by the solution-liquid-solid (SLS) mechanism. The nature of the axial or radial heterostructure obtained is strongly influenced by the growth sequence and related synthetic conditions. Compositionally graded ZnSe x Te 1-x wires, ZnSe-ZnTe axial heterostructures containing a ZnSe x Te 1-x transitional segment, ZnSe-ZnTe wires with sharp axial heterojunctions, and radial core-shell ZnSe-ZnTe quantum wires have been selectively prepared. The axial and radial quantum-wire heterostructures are characterized microscopically and spectroscopically.

Crystal-phase control is one of the most challenging problems in nanowire growth. We demonstrate that, in the solution-phase catalyzed growth of colloidal cadmium telluride (CdTe) quantum wires (QWs), the crystal phase can be controlled by manipulating the reaction chemistry of the Cd precursors and tri-n-octylphosphine telluride (TOPTe) to favor the production of either a CdTe solute or Te, which consequently determines the composition and (liquid or solid) state of the Bi x Cd y Te z catalyst nanoparticles. Growth of single-phase (e.g., wurtzite) QWs is achieved only from solid catalysts (y ≪ z) that enable the solution-solid-solid growth of the QWs, whereas the liquid catalysts (y ≈ z) fulfill the solution-liquid-solid growth of the polytypic QWs. Factors that affect the precursor-conversion chemistry are systematically accounted for, which are correlated with a kinetic study of the composition and state of the catalyst nanoparticles to understand the mechanism. This work reveals the role of the precursor-reaction chemistry in the crystalphase control of catalytically grown colloidal QWs, opening the possibility of growing phase-pure QWs of other compositions.

Ether à go-go (EAG) potassium channels display oncogenic properties. In normal tissues, EAG mRNA is almost exclusively expressed in brain, but it is expressed in several somatic cancer cell lines, including HeLa, from cervix. Antisense experiments against eag reduce cell proliferation in some cancer cell lines, and inhibition of EAG-mediated currents has been suggested to decrease cell proliferation in a melanoma cell line. Because of the potential clinical relevance of EAG, we investigated EAG mRNA expression in the following fresh samples from human uterine cervix: 5 primary cultures obtained from cancerous biopsies, 1 cancerous fresh tissue, and 12 biopsies of control normal tissue. All of the control cervical samples came from patients with negative pap smears. Reverse transcription-PCR and Southern-blot experiments revealed eag expression in 100% of the cancerous samples and in 33% of the normal biopsies. Immunochemistry experiments showed the presence of EAG channel protein i...

The interaction of actin filaments with myosin is crucial to cell motility, muscular contraction, cell division and other processes. The in vitro motility assay involves the motion of actin filaments on a substrate coated with myosin, and is used extensively to investigate the dynamics of the actomyosin system. Following on from previous work, we propose a new mechanical model of actin motility on myosin, wherein a filament is modeled as a chain of beads connected by harmonic springs. This imposes a limitation on the ‘stretching’ of the filament. The rotation of one bead with respect to its neighbors is also constrained in similar way. We implemented this model and used Monte Carlo simulations to determine whether it can predict the directionality of filament motion. The principal advantages of this model are that we have removed the empirically correct but artificial assumption that the filament moves like a ‘worm’ i.e. the head determines the direction of movement and the rest of ...

The fabrication and operation of biodevices require the accurate control of the concentration of the bioactive molecules on the surface, as well as the preservation of their bioactivity, in particular proteins that have a significant propensity for surface-induced denaturation. A method that allows the adsorption of proteins on 'combinatorial' micro/nano-surfaces fabricated via laser ablation of a thin metal layer deposited on a polymer that has been proposed allows for the up to 10-fold amplification of the protein adsorption on micro/nanostructures. This contribution studies the relationship between amplification of adsorption and protein molecular characteristics (total molecular surface; and charge-and hydrophobicity-specific surface).

Myosin–actin and kinesin–microtubule linear protein motor systems and their application in hybrid nanodevices are reviewed. Research during the past several decades has provided a wealth of understanding about the fundamentals of protein motors that continues to be pursued. It has also laid the foundations for a new branch of investigation that considers the application of these motors as key functional elements in laboratory-on-a-chip and other micro/nanodevices. Current models of myosin and kinesin motors are introduced and the effects of motility assay parameters, including temperature, toxicity, and in particular, surface effects on motor protein operation, are discussed. These parameters set the boundaries for gliding and bead motility assays. The review describes recent developments in assay motility confinement and unidirectional control, using micro- and nano-fabricated structures, surface patterning, microfluidic flow, electromagnetic fields, and self-assembled actin filame...

Magnetic resonance imaging (MRI) enables high-resolution non-invasive observation of the anatomy and function of intact organisms. However, previous MRI reporters of key biological processes tied to gene expression have been limited by the inherently low molecular sensitivity of conventional 1 H MRI. This limitation could be overcome through the use of hyperpolarized nuclei, such as in the noble gas xenon, but previous reporters acting on such nuclei have been synthetic. Here, we introduce the first genetically encoded reporters for hyperpolarized 129 Xe MRI. These expressible reporters are based on gas vesicles (GVs), gas-binding protein nanostructures expressed by certain buoyant microorganisms. We show that GVs are capable of chemical exchange saturation transfer interactions with xenon, which enables chemically amplified GV detection at picomolar concentrations (a 100-to 10,000-fold improvement over comparable constructs for 1 H MRI). We demonstrate the use of GVs as heterologously expressed indicators of gene expression and chemically targeted exogenous labels in MRI experiments performed on living cells.

Mineralization of formic acid from catalytic nitrate reduction effluent by UV-based and electrochemical processes Fernanda Miranda Zoppas (Formal analysis) (Investigation) (Writing -original draft) (Methodology), Salatiel Wohlmuth da Silva (Writingreview and editing) (Formal analysis) (Methodology), Thiago Favarini Beltrame (Writing -original draft) (Methodology), Fernanda Albana Marchesini (Writing -review and editing) (Supervision) (Funding acquisition), Andr éa Moura Bernardes (Writing -review and editing) (Funding acquisition), Eduardo Mir ó (Writing -review and editing) (Supervision) (Funding acquisition)

Nitrate is a chemical species usually present in water, lakes and rivers and in high concentration can be dangerous to the human health. In this work, palladium-coated alumina pellets associated to a copper plate electrode were tested, in an electrochemical dual-chamber cell (DCC), for the treatment of solutions containing high nitrate concentration. The tests evaluated how Pd catalyst, current density and pH have an effect on the reduction reaction and on the formation of nitrite, ammonium and gaseous compounds. It was possible to observe that the Pd catalyst has an influence on the products formed, with an increase on the gaseous compounds production. The current density plays also an important role on the treatment, considering that, by applying 1.1 mA cm -2 , 59 % of nitrate reduction was observed, while with 1.5 mA cm -2 the reduction was 64 %. The highest selectivity to gaseous compounds and lower selectivity to nitrite were obtained using alumina pellets coated with 2.5 % wt. of Pd, a current density of 1.5 mA cm -2 and with pH adjustment (6.0-6.5). In these conditions, a nitrate reduction of 49 % was obtained, with a selectivity of 64 % to gaseous compounds, 1% to nitrite and 35 % to ammonium. The main novelty of this work is the reduction cell design, by the use of a dual chamber cell and with the catalyst in pellets form. This cell would be suitable for scaling-up the process.

Water with high concentration of nitrate may cause damage to health and to the environment. This study investigated how concentration, current density, flow, pH, the use of Pd/In catalyst and operating mode (constant current density and constant cell potential) have an influence in the electrochemical reduction of nitrate and in the formation of gaseous compounds using copper electrode. Experiments were performed in two-compartment electrolytic cells separated by a cationic membrane with nitrate model solutions prepared as a surrogate of concentrated brines from membrane desalination plants. The results show that the electroreduction process has potential for reduction of nitrate and that it is influenced by the operational conditions. The best conditions found for the treatment -with satisfactory reduction of nitrate, formation of gaseous compounds and Downloaded by [Australian Catholic University] at 19:08 18 August 2017 reproducibility -were at nitrate concentrations of 600 and 1000 mg.L -1 , current density of 1.1 mA.cm -2 and without pH control, since in these conditions the production of gaseous compounds is higher than the production of nitrite. When Pd/In catalyst was used, the nitrate reduction was 50% after 6 hours of experiment and the predominant product were gaseous compounds. When compared to the experiment without the catalyst, the arrangement with Pd/In was the most efficient one.

The electrochemical synthesis of ferrate(VI) by the oxidation of iron compounds from alkaline 10 M KOH electrolytes on a boron-doped diamond electrode was examined by cyclic voltammetry between the potentials of the hydrogen evolution reaction and the oxygen evolution reaction. It was shown that the anodic current peak that appeared in iron-free electrolyte at a less positive potential than the potential of the oxygen evolution probably coincides with oxidation of hydrogen in >CH 2 groups and C-sp 2 graphite impurities with formation of >C=O groups in a C-sp 3 diamond structure. Addition of Fe(III) compounds to the electrolyte provoked the formation of an anodic wave on the cyclic voltammograms in the potential region that correlates with the generation of ferrate(VI). It is concluded that the direct electrochemical synthesis of Fe(VI) at a boron-doped diamond anode is possible because of the less positive potential of ferrate(VI), FeO , formation with respect to the potential of the oxygen evolution reaction. The presence of ferrate(VI) in the electrolyte, formed after anodic polarization of the boron electrode in 10 M KOH electrolyte saturated with Fe(III) at 0.9 V against Hg/HgO electrode, was proven by UV-Vis spectrometry.

A new dithiolene ligand with 3,5-dibromo substituted phenyl groups was designed and synthesized. The protected form of the ligand was reacted with a nickel salt providing neutral Ni(S 2 C 2 (3,5-C 6 H 3 Br 2 ) 2 ) 2 and anionic [Ni(S 2 C 2 (3,5-C 6 H 3 Br 2 ) 2 ) 2 ] -isolated as a Bu 4 N + salt. Both were characterized by UV-visible and IR spectroscopy and compared with the similar known molecular systems. They exhibit intense low-energy transitions that are characteristic of such systems. The electrochemical behavior of these molecules was investigated by cyclic voltammetry.

The densities, ultrasonic velocities and viscosities of sodium dodecyl sulphate (SDS) in water and in aqueous L-cysteine solutions have been measured as a function of SDS concentration at five equidistant temperatures ranging from 293.15 K to 313.15 K. The density data were used to calculated the apparent molar volume, v, the limiting apparent molar volume, 0 v  and experimental slopes, Sv,derived from the Masson equations. The apparent molar adiabatic compressibilies, s  were also calculated by using both the density and ultrasonic velocity data. The viscosity data were employed to determine the viscosity B-coefficients, and the free energies, ΔG ≠ , enthalpies, ΔH ≠ and entropies, ∆S ≠ of activation using the Nightingale and Benck, and Eyring equations. The structural properties of SDS in water and aqueous L-cysteine were studied by using

Quaternary chalcopyrite semiconductors, Cu2ZnSnS4 (CZTS) and Cu2ZnSnSe4 (CZTSe), have attracted increasing attention for photovoltaics (PV) application in recent years. However, due to the cell architecture borrowed from CuInxGa(1-x)Se2 (CIGS) devices, the open-circuit voltage is the limiting factor preventing further increases in solar cell efficiency. In the present study, band edge energies of Cu2ZnSnS4 and Cu2ZnSnSe4 were analysed electrochemically in order to show band energy alignments of CZTS and CZTSe. The electrochemical steady-state potential windows were also investigated; this provides vital information for various applications of both materials. The valence band energy offset between CZTS and CZTSe was found to be 0.5 eV. Compared with the flat band potential of CdS (-0.8 V vs Ag/AgCl), the open circuit potential in the dark between CZTS and CdS is therefore 0.4 V and 0.9 V for CZTSe. Moreover, from chronoamperometric measurements using an electrochemical field-effect transistor, the conductivity of CZTSe is found to be three orders higher than CZTS, which proves that CZTSe is significantly better for charge transfer.

Pl e a s e n o t e: C h a n g e s m a d e a s a r e s ul t of p u blis hi n g p r o c e s s e s s u c h a s c o py-e di ti n g, fo r m a t ti n g a n d p a g e n u m b e r s m a y n o t b e r efl e c t e d in t hi s v e r sio n. Fo r t h e d efi nitiv e v e r sio n of t hi s p u blic a tio n, pl e a s e r ef e r t o t h e p u blis h e d s o u r c e . You a r e a d vis e d t o c o n s ul t t h e p u blis h e r's v e r sio n if yo u wis h t o ci t e t hi s p a p er. This ve r sio n is b ei n g m a d e a v ail a bl e in a c c o r d a n c e wi t h p u blis h e r p olici e s. S e e h t t p://o r c a . cf. a c. u k/ p olici e s. h t ml fo r u s a g e p olici e s. Co py ri g h t a n d m o r al ri g h t s fo r p u blic a tio n s m a d e a v ail a bl e in ORCA a r e r e t ai n e d by t h e c o py ri g h t h ol d e r s .

Hybridising 2D materials into 3D aerogels have attracted considerable interest in ultralight electrochemical energy storage devices. However, to optimise the device structure for more efficient charge storage and transport, a better understanding of the ratio-dependent hybridisation process and interface charge transfer mechanisms are highly required. Here, we perform a comprehensive study to elucidate the fundamental process during the reduced graphene oxide (rGO) and carbon nanotube (CNT) hybridisation, which enabled the fabrication of a rational-designed rGO/CNT hybrid aerogel (GCA) with a record energy storage performance beyond previously reported works. Based on spectroscopy and microscopy analysis, we found the hydrophilic and hydrophobic transition of GO which eliminates the surface-functionalised oxygen-containing moieties, is the origin of the π-π stacking hybridisation between rGO and CNTs. Moreover, we found the different amount of CNTs 'solder' in-between rGO sheets can offer GCA distinct mechanical elasticity, ion diffusion resistance and specific capacitance. As illustrated in the electrochemical impedance spectroscopy (EIS) and charge/discharge analysis, we found GCA 2-2 (rGO:CNT=2:2) display the best gravimetric capacitance of 117 F•g -1 at a discharge current density of 1 A•g -1 , which help us to fabricate an ultra-flyweight supercapacitor with a large energy density of 3.53 Wh•kg - 1 at a power density of 283.4 W•kg -1 .

The oxygen evolution reaction (OER) is critical in electrochemical water splitting and requires an efficient, sustainable and cheap catalyst for successful practical applications. A common development strategy for OER catalysts is to search for facile routes for the synthesis of new catalytic materials with optimized chemical compositions and structures. Here, we report nickel hydroxide Ni(OH)2 two-dimensional (2D) nanosheets pillared with zero-dimensional (0D) polyoxovanadate (POV) nanoclusters as an OER catalyst that can operate in alkaline media. The intercalation of POV nanoclusters into Ni(OH)2 induces the formation of a nanoporous layer-by-layer stacking architecture of 2D Ni(OH)2 nanosheets and 0D POV with a tunable chemical composition. Our nanohybrid catalysts remarkably enhance the OER activity of pristine Ni(OH)2. The present findings demonstrate that the intercalation of 0D POV nanoclusters into Ni(OH)2 is effective for improving water oxidation catalysis and represents a potential method to synthesize novel, porous hydroxide-based nanohybrid materials with superior electrochemical activities.

Nowadays the research is focused on ecological friendly catalysts to be used in dyes decolourisation as an important target in the textile industry. In the presented work some copper complexes were prepared by immobilization of Cu (II) on the chitosan matrix. The oxidation of model acid dye ANTD (anthraquinone dye) with hydrogen peroxide catalyzed by these Cu complexes has been investigated and the kinetic of ANTD oxidation was measured. It was found, that the reactivity of catalyst was in the relation with the amount of copper incorporated in the complex. The rate of the oxidative reaction depends also on the concentration of hydrogen peroxide in the reaction solution. Prepared copper complexes were compared in the dye decolourisation efficiency. In the best reaction conditions the anthraquinone dye decolourisation was over 95 %. Obtained results leads us to assume that heterogeneous redox catalysis process could be relatively easy, cheap and useful way to remove textile dyes from wastewater effluents.

Corrosion in concrete prevents in-situ observation, necessitating models to provide insight into the local reaction currents. We present a computational method for predicting corrosion rates of reinforcements within concrete under natural conditions, i.e. requiring the corrosion current to be supported by equal cathodic currents. In contrast to typical corrosion models, where these two counteracting currents are required to be co-located, we allow these currents to be separated such that pitting corrosion can be supported by cathodic reactions over a much larger area. Pitting corrosion is investigated, elucidating the effects of the concrete porosity and water saturation, the presence of dissolved oxygen, and chlorine concentration within the pore solution. The presented model is capable of capturing the dynamic growth of acidic regions around corrosion pits, showing the limited region over which the hydrogen evolution reaction occurs and how this region evolves over time. The ability of oxygen to diffuse towards the metal surface due to increased porosity is seen to have a major effect on the corrosion rate, whereas changes in the chlorine concentration (and thus changes in the conductivity of the pore solution) play a secondary role. Furthermore, external oxygen is seen to enhance corrosion but is not required to initialise and sustain acidic corrosion pits.

The application of scanning electrochemical techniques to evaluate and spatially resolve corrosion activity has progressively increased over the last 20 years. Electrochemical scanning techniques are based principally upon the assumption that localised corrosion, where the anodic and cathodic processes take place at separate sites, can be represented as point sources. The electric field generated by sites of localised corrosion consists of equipotential lines which can be measured and graphically represented as a contour map. Many modern day systems use either a static or vibrating reference or quasi-reference electrode, to measure the electric field, more specifically the field normal (perpendicular) to the surface. The latter of these systems, namely the vibrating electrode, allows for improved resolution and a lower minimum detectable signal. The following paper presented here discusses a study conducted to evaluate the influence of the operating parameters on the resolution and minimum detectable signal measurable using a scanning vibrating electrode system. Measurement of the electric field generated at a point source, namely, a gold point in space (PIS) electrode, is used to evaluate the effect of parameters such as probe scan speed, vibration amplitude and probe-sample distance on the peak output potential and the resolution, defined here as the ratio of the peak potential to the full width at half-maximum peak potential (FWHM).

The objective of this work was to determine the parameters that affect the mass transport and the distribution of species in microcapillaries close to the specimen surface. Local experiments were carried out under static and flow conditions on type 316L stainless steel in 1.7 M NaCl, pH = 3, by means of the electrochemical microcell and the scanning droplet cell technique. The polarisation behaviour of pure iron (used as a model system) in an aqueous environment was calculated adopting a finite element approach and was compared to the experimental results. The corrosion system consists of three parallel electrochemical reactions: the oxygen reduction reaction (ORR), the hydrogen evolution reaction (HER) and iron dissolution.

In this study, direct borohydride fuel cells (DBFCs) potentialities are evaluated. These emerging systems make it possible to reach maximum powers of about 200 mW cm -2 at room temperature and ambient air (natural convection) with high concentrated borohydride solutions. On the other hand, a part of borohydride hydrolyses during cell operating which leads to hydrogen formation and fuel loss: the practical capacity represents about only 18% of the theoretical one. In order to improve fuel efficiency, thiourea is tested as an inhibitor of the catalytic hydrolysis associated with BH 4 electro-oxidation on Pt. The practical capacity is drastically improved: it represents about 64% of the theoretical one. Against, electrochemical performances (I-E curves) are affected by the presence of thiourea. Last, both playing with platinum anodic mass loading and the nature of catalyst, a good compromise has been found in terms of both specific capacity and power.

Some scientific studies report that the use of nanosized cathode materials can improve the electrochemical performances of a battery. In fact, these materials can open new and important perspectives for cathode materials such as their use for power applications or for technologies for which an optimized interface with the electrolyte is required (e.g all solid state battery or polymer battery). However, the high scale production and the processing of these powders to obtain dense electrodes are difficult. In this study, submicronic particles of LiNi 1/ 3 Mn 1/3 Co 1/3 O 2 are synthesized using an easy and scalable coprecipitation synthesis protocol. Isolated particles of 200 nm are obtained and are fully characterized. The non-agglomerated morphology of this material improves the accessibility of the lithium insertion planes, and consequently, the high C-rate behavior is clearly improved as compared to classic agglomerate materials. The difficult processing of submicronic particles is overcome thanks to an environmentally-friendly water-based formulation. Proof-of-concept Li-ion cells have been realized. Although submicronic particles are used, the cell is manufactured with a cathode loading of 18.8 mg cm -2 which is relevant for commercial application.

In this study, direct borohydride fuel cells (DBFCs) potentialities are evaluated. These emerging systems make it possible to reach maximum powers of about 200 mW cm -2 at room temperature and ambient air (natural convection) with high concentrated borohydride solutions. On the other hand, a part of borohydride hydrolyses during cell operating which leads to hydrogen formation and fuel loss: the practical capacity represents about only 18% of the theoretical one. In order to improve fuel efficiency, thiourea is tested as an inhibitor of the catalytic hydrolysis associated with BH 4 electro-oxidation on Pt. The practical capacity is drastically improved: it represents about 64% of the theoretical one. Against, electrochemical performances (I-E curves) are affected by the presence of thiourea. Last, both playing with platinum anodic mass loading and the nature of catalyst, a good compromise has been found in terms of both specific capacity and power.

In the laboratory-scale experiments, treatment of baker's yeast production wastewater has been investigated by electrocoagulation (EC) using a batch reactor. Effects of the process variables such as pH, electrode material (Fe and Al), current density, and operating time are investigated in terms of removal efficiencies of chemical oxygen demand (COD), total organic carbon (TOC), turbidity, and operating cost, respectively. The maximum removal efficiencies of COD, TOC and turbidity under optimal operating conditions, i.e.

In the present study, electrocoagulation process employing Fe-Al composite electrode was applied for treatment of different types of textile wastewaters. Effect of major operating parameters such as pH, reaction time, current density, voltage and inter-electrode distance were investigated for chemical oxygen demand (COD) and colour removal efficiency. The process was found promising and produced more than 90% COD and colour removal efficiency at optimised operating conditions of pH 8, reaction time 80 min, current density 20 A/m 2 with an inter-electrode distance of 3 cm. Robustness of the process was investigated on real and anaerobically pretreated textile wastewater. For real textile effluents, the process produced approximately 99% colour removal efficiency, creating virtually colourless solution even at a lesser reaction time of 60 min. Electrocoagulation effectively detoxified the anaerobically pre-treated textile wastewater by eliminating 78% of aromatic amines within a reaction time of 180 min.