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A 1-ethyl-3-methylimidazolium tetrafluoroborate (EMI–BF4) ionic liquid is introduced into an electrolyte as a functional additive to enhance the low-temperature performance of LiNi0.5Co0.2Mn0.3O2 (NCM523)/graphite batteries. Linear sweep voltammetry (LSV), cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS) tests show that EMI–BF4 can be oxidized in advance and produce low impedance solid-electrolyte interphase (SEI) films on the electrode surfaces. Compared with the batteries without the EMI–BF4 additive, the capacity retention of the NCM523/graphite batteries with 1% EMI–BF4 additive is enhanced from 82.3% to 93.8% after 150 cycles at a low temperature of −10 °C. In addition, at −30 °C, the discharge capacity of the batteries with 1% EMI–BF4 additive is nearly doubled. And at the room temperature of 25 °C and after 400 cycles, the capacity retention also increases from 80.3% to 85.9%, and the coulomb efficiency remains at approximately 100%. These results demonstrate that EMI–BF4 used as a functional electrolyte additive has promising prospects for application to improve the low-temperature performance of NCM523-based lithium-ion batteries.

Different cobalt phases are deposited on graphite discs from CoSO4 baths in absence and presence of equimolar concentration of citrate ions, Co/G and Co(cit)/G, respectively. The prepared electrodes are subjected to different electrochemical studies. Benchmark recommends the use of the overpotential required to achieve current density of 10 mA.cm−2 ( η t = 0 ) in linear sweep voltammetry, LSV, at 10 mV.s−1 as an activity parameter for oxygen evolution reaction, OER. The values of η t = 0 equal 0.443 and 0.440 for Co/G and Co(cit)/G, respectively. This work suggests an activation routine based on the observed sequential enhancing of η t = 0 values through successive cyclic voltammetry in 1 M NaOH. Satisfactory η t = 0 values of 0.437 and 0.394 V are obtained for the activated electrodes prepared in absence and presence of citrate anions, respectively. All the prepared electrodes show noteworthy stability over 2hrs. The values of overpotential after 2 hrs η t = 2 h in 1 M NaOH reveals higher efficiency for the electrodes prepared from citrate-containing bath rather than citrate free bath. The morphology and the structure of the optimum electrodes are characterized. RRDE and eQCM studies clarify the role of the citrate anion in controlling the deposited cobalt phases. The OER catalytic activities are correlated with the deposited cobalt phase structure for the prepared electrodes.

Although deep eutectic solvents (DES) and ethylene glycol (EG) electrolytes are gaining ground as media for the electrodeposition of metals, the influence of these electrolytes on the electrode and electrodeposits has not been elaborated before. In this work, we investigate how choline chloride: ethylene glycol based (ChCl:EG) electrolytes interact with the glassy carbon (GC) working surface at different potentials and, how these interactions change during the electrodeposition of iron from 1:2 and 1:4 ChCl:EG electrolytes. GC substrates are exposed to both electrolytes in absence of iron in order to study the pure electrolyte-substrate interactions. Linear sweep voltammetry was used to determine the potential range in which the different reactions occur, while time-of-flight secondary ion mass spectrometry (ToF-SIMS) was used to detect and identify the molecules adsorbed on the surface. In all systems, there is an accumulation of either choline or its derivatives on the electrode surface, with 1:4 ChCl:EG electrolytes showing different decomposition products from 1:2 ChCl:EG electrolytes. Choline accumulation and decomposition was also found on iron electrodeposits. The electrolyte composition has a major impact on the chemical speciation of iron, and on the deposit's adherence to the substrate. These are two crucial characteristics that define the efficiency of iron deposition from DES.

We interrogated the effects of in-situ electrochemical chlorination with Ti/IrO2 anodes on physico-chemical properties of mixed liquor and fouling in membrane bioreactors (MBRs). Linear sweep voltammetry with variable concentrations of model organic foulant (alginic acid) indicated negligible direct oxidation. Batch electrolysis under current densities (j) up to 1.2 mA/cm2 further indicated that free chlorine (FC) primarily mediates transformation of dissolved compounds such as NH4+ N and organic carbon (DOC) including protein and soluble microbial product (SMP, as noted in excitation-emission matrix, EEM). Owing to infinitesimal steady-state concentrations of FC under electrolytic generation, diffusion of FC determined the transformation kinetics in bulk, while floc/cell breakage and mineralization of extracellular polymeric substances (EPS) were marginal. Decay of negatively charged functionalities was found to compete with carbonyl generation on aromatic carbons (noted by red shift of EEM peak), which determined the magnitude of floc zeta-potential. A cathodic scale deposition was presumed to bring about PO43− removal and stimulate sludge flocculation. This study evinced that an increased floc size coupled with removal and/or transformation of hydrophobic DOC would contribute to the alleviated membrane fouling. However, significant decreases in microbial utilization rates of DOC under exposure to j > 0.8 mA/cm2 accelerated fouling during continuous operations of MBRs.

We study the ion-conductive and electrochemical properties of concentrated poly (ethylene carbonate) (PEC)-based electrolytes with Li salt concentrations greater than 100 mol%. An end-capped PEC having acetate groups (PEC-Ac) was synthesized as a novel polymer matrix for improving the thermal stability and oxidative stability. A concentrated PEC-Ac electrolyte with 120 mol% of LiFSI had a good conductivity of approximately 10−6 S/cm at 40 °C with an excellent Li transference number (t+) of 0.8. Linear sweep voltammetry measurement for the PEC-Ac electrolyte indicates that the oxidation tolerance is more than 5 V, and is greater than that of the original PEC-based electrolyte. A battery test for the LiFePO4 cell using the PEC-Ac electrolyte was conducted for the first time, finding good capacities ranging from 130 to 160 mAh/g and stable cyclability for more than 60 cycles.

A novel quaternary ammonium salt—1,1-dimethylpyrrolidinium tetrafluoroborate (DMPBF4), tetraethylammonium tetrafluoroborate (TEABF4), and spiro-(1,1′)-bipyrrolidinium tetrafluoroborate (SBPBF4) were prepared and dissolved in acetonitrile (ACN) and propylene carbonate (PC) for electrolyte systems of electric double-layer capacitors (EDLC). Physical properties such as thermal stability, solubility, and ionic conductivity were determined and six different electrolyte systems with 1 M concentration were electrochemically evaluated by linear sweep voltammetry, cyclic voltammetry, galvanostatic charge-discharge, and float test. To investigate the origin of the physical and electrochemical properties at the molecular level, quantum calculations for the chemical species in the electrolytes were also carried out. Compared to the standard electrolytes TEABF4 and SBPBF4, the novel DMPBF4 electrolyte exhibits a higher gravimetric capacitance, superior rate capability, and improved cycling stability. The energy and power density of EDLCs using DMPBF4 in the ACN electrolyte reach 40.61 Wh kg−1 and 8.09 kW kg−1, respectively, at the working voltage of 3.0 V. Moreover, EDLCs with DMPBF4 in ACN (PC) retain 87.9% (87.5%) of their initial capacitance after 1000 h of float testing at 3.0 V. The results indicate that DMPBF4 can be a promising electrolyte salt for EDLC application.

A perfluorinated composite membrane incorporating an organic antioxidant was prepared to improve the chemical durability of a polymer electrolyte fuel cell. Bipyridine and benzoquinone (BQ) were added as organic antioxidants, and the oxidative stability of the composite electrolyte membranes containing them was evaluated via accelerated aging tests, i.e., an ex situ Fenton's test and in situ open-circuit voltage (OCV)-holding test. The effects of the antioxidants in the Fenton's test were verified using scanning electron microscopy, fluorine ion detection, Fourier-transform infrared spectroscopy, and tensile strength measurements. Moreover, a commercial membrane, NRE211, and a composite membrane, Nafion-BQ, were incorporated into a membrane electrode assembly (MEA) that then underwent an OCV-holding test for 500 h. The change in the MEA state over time was analyzed using cyclic voltammetry and linear sweep voltammetry. While NRE 211 showed a significant reduction in OCV from 300 h, Nafion-BQ maintained a stable OCV for 500 h. Hence, the organic antioxidants added to the electrolyte membrane effectively improved the oxidative stability of the proton exchange membrane fuel cell without sacrificing the ionic conductivity of the perfluorinated electrolyte membrane.

The present paper reports the effect of nitrogen modification on photoelectrochemical (PEC) water oxidation behavior of Bi2O3 semiconductor thin film. The semiconductor particles were synthesized via hydrothermal route using Bi(NO3)3 as a Bi3+ ion precursor and urea as the nitrogen source followed by drop-cast the particles and annealing the film at 600 °C. The synthesized Bi2O3 exhibited band gap energy of 3.01 eV, calculated from the UV–visibleabsorption spectrum which decreases to 2.75 eV through N-modification. Water oxidation behavior of the material has been tested through linear sweep voltammetry under periodic illumination. Highest photo-current of 180 μAcm−2 has been measured for water oxidation reaction at 0.95 V vs. Ag/AgCl, under illumination of 35 mWcm−2. N-incorporation can enhance the photocurrent up to 50% whereas the visible responsiveness of the material improves significantly as confirmed from electrochemical action spectra and UV–visible absorption spectra. The photocatalytic activity of the semiconductor particles was confirmed through decoloration of Rhodamine-B dye, by spectrophotometric measurements.

In this study, we report an electrochemical study based on nanocellulose (NC) and single-walled carbon nanohorns (SWCNH). SWCNH and NC ensure large surface area, good conductivity, high porosity and chemical stability, becoming attractive for electrodes. The materials were characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR), Scanning Electron Micrograph (SEM), Transmission electron microscopy (TEM), dynamic light scattering (DLS) and zeta potential. Using XRD and FTIR it was possible to observe particular characteristics of NC and SWCNH. The presence of dahlia-like assemblies on the NC surface was observed by MEV and TEM. Then, we investigated the electrochemical behavior of NC-SWCNH, which showed the excellent results when it was used guanine and adenine, as proof of concept, by using cyclic and linear sweep voltammetry (LSV). LSV was also employed for simultaneous detection resulting in limits of detection of 1.7 × 10−7 mol L−1 and 1.4 × 10−6 mol L−1, for guanine and adenine, respectively. In addition, the proposed electrode was applied for determination of both bases in synthetic human serum and fish sperm. We demonstrate that it is possible to use NC, a renewable material, in conducting thin films with SWCNH, and due to simplicity in the preparation and high conductivity, this new thin film could be extended for others electrochemical purposes such as sensing and biosensing.

In this work, a simple, selective and stable strategy for encapsulation of triangular ruthenium nanoplates (RuNPs) through o-Phenylenediamine (oPD) polymerization on graphene modified screen-printed carbon electrode (SPEGPH) was demonstrated. o-Phenylenediamine polymer (PoPD) film provided a suitable microenvironment for RuNPs immobilization. Synthesis of RuNPs was characterized by transmission electron microscope (TEM) and electrochemical methods including cyclic voltammetry (CV) and linear sweep voltammetry (LSV). Encapsulation or incorporation of RuNPs through PoPD were carried out following three different strategies and the resulting platforms were investigated using scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX). The electrocatalytic performance of RuNPs-PoPD-GPH platform was demonstrated using the NADH oxidation as model electrochemical reaction. The incorporation of 18 ± 3 nm RuNPs onto PoPD decreased the NADH oxidation potential by ca. 350 ± 5 mV in comparison to bare SPEGPH as well as a remarkable enhance of sensitivity to NADH detection. Therefore, RuNPs have provided electron transfer with a strong catalytic effect for NADH oxidation representing a promising application in sensors.

A new nickel-foam (Ni-F) based cathode was elaborated by coating nitrogen-doped porous carbon (CN/Ni-F) and applied to the electro-Fenton (EF) treatment of sulfathiazole (STZ, a target pollutant). Both Fourier transform infrared spectra (FITR) and X-ray photoelectron spectroscopy (XPS) results confirmed the abundant presence of surface oxygen/nitrogen-containing functional groups after nitrogen-doped porous carbon (CN) introduction. Linear sweep voltammetry (LSV) showed an improvement of the electroactive surface area, while according to electrochemical impedance spectroscopy (EIS), the charge transfer resistance decreased from 95.7 Ω to 19.7 Ω after CN modification. Results showed that the modified CN/Ni-F cathode, achieved a 15 times improvement of H2O2 accumulation, which represented 13.8 times higher current efficiency (CE) for H2O2 generation via two-electron oxygen reduction. Its H2O2 generation ability was comparable to other carbonaceous cathodes like graphite and carbon cloth. Furthermore, CN/Ni-F also enhanced the electrocatalytic reduction of Fe3+. Regarding STZ degradation by EF, the apparent kinetic rate constant (kapp = 1.15 × 10−2 min−1) was 5.22 times higher than the kinetic rate constant obtained with the unmodified Ni-F cathode (kapp = 2.2 × 10−3 min−1), thus confirming the superiority of CN/Ni-F electrode. In addition, a possible STZ degradation pathway was proposed according to the intermediates identified during EF (aromatic by-products and inorganic ions (SO42−, NH4+ and NO3−)). Finally, 5 cycles experiments showed that the CN/Ni-F cathode had a good stability in terms of H2O2 accumulation and STZ degradation.

Activated carbon (AC) is an inexpensive catalyst for oxygen reduction in an air cathode of microbial fuel cells (MFCs). In the AC-based cathode, carbon black (CB) is used as a conductive supporting material. In this study, it was hypothesized cathodic performance would increase if reduced graphene oxide (rGO) replaces CB in an optimum ratio. rGO replaced CB in the four different weight ratios of rGO toCB: 0:30 (rGO0); 5:25 (rGO5); 15:15 (rGO15); 30:0 (rGO30). Maximum power density was the best in rGO15 (2642 mW/m2) followed by rGO5 (2142 mW/m2). In the optimum external resistance operation, rGO5 and rGO15 showed similar power (∼1060 mW/m2), higher than the others. Linear sweep voltammetry, cyclic voltammetry, and impedance spectroscopy also showed that the optimal rGO additions improved cathodic performance and reduced cathodic internal resistance. Due to the flatter and wider shape of rGO and 5 times higher electrical conductivity than CB, the rGO addition improved the cathodic performance, but the complete replacement of CB with rGO decreased the cathodic performance due to the increased thickness and the morphological crack. The optimum rGO addition is a simple and effective method for improving cathodic performance.

A naturally rich, low cost electrocatalyst of spinel CoMn2O4 doped reduced graphene oxides (CoMn2O4/rGO) is prepared as oxygen reduction reaction (ORR) electrocatalyst. The CoMn2O4 nanoparticles (∼10 nm) disperse uniformly on the rGO nanosheets via in-situ hydrothermal synthesis, endowing the CoMn2O4/rGO electrocatalyst a large Brunauer-Emmet-Teller surface area (78.4 m2 g−1) and abundant Co3+/Co2+, Mn3+/Mn2+ and Mn4+/Mn3+ electroactive sites, resulting in faster electron transport and improved electrochemical activity for ORR. The mechanism of oxygen reduction for CoMn2O4/rGO catalyst proceeds through both two-electron and four-electron pathways while the former pathway dominates according to linear sweep voltammetry analysis. These nanocomposites are doped on graphite felt to act as air-cathode in a double-chambered microbial fuel cell (MFC). Benefiting from the more positive reduction potential, higher electron conductivity and reduced charge-transfer resistance, the MFCs using GF-CoMn2O4/rGO air-cathodes exhibit much better cell performance than those using GF-CoMn2O4 and bare GF air-cathodes. The MFC using GF-CoMn2O4/rGO-8.0 reaches the maximum power output of 361 mW m−2 and open circuit potential of 0.822 V. The excellent catalytic activity makes GF-CoMn2O4/rGO a promising air-cathode for practical applications of MFC.

Sulfur and nitrogen containing groups have been bonded to carbon in graphite felt electrodes using a hydrothermal treatment with ammonium persulfate (APS) for use in an aqueous all-vanadium redox flow battery (VRB). Our results reveal that the hydrothermal treatment with APS is a very effective means to attach both sulfur and nitrogen groups to the surface of graphite felt, and as a result, the inclusion of these groups significantly improved the voltaic efficiencies (∼95%), discharge capacities (>400 mAh), and capacity retention (∼83%) of these batteries at current density of 50 mA/cm2. The direct addition of reactive sulfur and nitrogen groups also substantially extended the range of current densities available to the battery (in excess of 200 mA/cm2) without sacrificing capacity and capacity retention. Linear sweep voltammetry indicated that APS treated graphite felts showed an electrochemical enhancement factor over double that of untreated pristine graphite felts. These results suggest that the direct addition of sulfur and nitrogen containing groups on the graphite felt as a simple and effective method for improving the performance of all-vanadium redox flow batteries.

An ex-situ potentiometric titrations were normally performed using an oxidation/reduction potential (ORP) electrode to monitor the electrochemically generated active electron mediators, either oxidants or reductants, in a mediator generation plant. In the present investigation, an attempt was made to monitor electron mediator [Ni1+(CN)4]3- (Ni(I)) in-situ in a high electrolyte concentration (9 M KOH) during its electrochemical generation. A ring type flow cell developed using a 0.6 cm diameter electrode was tested on a standard redox couple of [Fe3+(CN)6]3- (Fe(III))/[Fe2+(CN)6]4- (Fe(II)) at different ratios during solution flow. The found results suggested that direct determination of an electrochemically prepared electron mediator is possible using a potentiometric method. A periodical potential change in the in-situ linear sweep voltammetry of electrogenerated Ni(I) during its electrochemical generation allowed the direct determination of electrogenerated Ni(I) by the ring type flow cell. A calibration plot derived from chemically synthesized Ni(I) using an ex-situ potentiometric titration or UV–visible spectra was used to monitor electrogenerated Ni(I) by the in-situ method. The electrochemically generated Ni(I) concentration detected in the 0–4.5 mmol/L region that followed non-Nernstian behavior. A change in the Ni(I) concentration during N2O removal at the scrubber column suggesting that air pollutant removal can be monitored using the in-situ flow sensor cell, once how many electron involved in the removal process.

The present research is dedicated to the description of the effects of AC electrochemical incorporation of silver on the compositional, morphological and structural characteristics of the obtained modified anodic aluminum oxide (AAO) layers. The AC electrochemical Ag-incorporation was performed on preliminary galvanostatically anodized technically pure (AA1050) aluminum alloy for different durations (up to 900 s). The obtained Al-O-Ag combined layers were submitted to systematic characterizations in order to determine the incorporation efficiency and the respective process mechanism. The performed analyses comprised subsequent determination of: (i) chemical composition, (ii) surface topology and roughness, (iii) layer thickness and uniformity, and (iv) electrochemical behavior in 3.5% NaCl model corrosive medium. The Ag content and the respective incorporation efficiency were estimated by Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES). The topological and morphological modifications of the films were determined by Atomic Force Microscopy (AFM) and Scanning Electron Microscopy (SEM), respectively. The morphological characterizations were completed by surface and cross-sectional Energy Dispersion X-ray (EDX) analyses thus determining the film thicknesses and elements distribution. All characterizations using these analytical methods were finalized by studying the performance of these films in a model corrosive medium by Electrochemical Impedance Spectroscopy (EIS) and Linear Sweep Voltammetry (LSV). The further comprehensive data analysis of the obtained results has enabled to create a conceptual model for the description of the correlations between the Ag-incorporation duration and the resulting compositional, topological and structural features, and the resulting film properties and performance. The AC electrochemical Ag-incorporation has a relatively low efficiency and proceeds with gradual silver deposition in the bottoms of the pores and its further accumulation in an upward direction. The cause for the observed low efficiency is related to the simultaneous occurrence of AAO layer growth and dissolution during the AC polarization, which result in topological and roughness variations, as well.

It is essential to design an oxygen evolution reaction (OER) electrocatalyst with smaller overpotential to improve water electrolyzer efficiency. Here, we report a simple method to incorporate nickel hexacyanoferrate into the three-dimensional (3D) graphene aerogel (GA) structure (NiHCF/GA), through which we have derived OER active FeNi-P/GA catalyst by heating with the phosphide source. Structural characterization data disclosed that the NiHCF derived FeNi-P particles were uniformly distributed in the 3D GA network. The obtained FeNi-P/GA catalyst exhibits precursor ([K3Fe(CN)6] and NiCl2) concentration-dependent electrocatalytic activity towards OER. Linear sweep voltammetry (LSV) study shows OER on the optimized FeNi-P/GA catalyst surface commenced at 1.46 V vs. RHE and demands only 280 mV overpotential to achieve the benchmark current density of 10 mA.cm−2. Also, the FeNi-P/GA catalyst displayed a Tafel slope of 43 mV.dec−1, suggesting its superior OER performance in alkaline condition.

Reliability and long-term performance are the key features of modern energy storage and conversion devices. The long-term stability depends entirely on the electrochemical and corrosion properties of device components. Single-phase mesoporous Ni-rich Ni-Pt thin films have shown to be a promising electrocatalyst for hydrogen evolution reaction (HER) and therefore with potential application in fuel cells, water electrolysers or similar devices. The HER activity of the mesoporous Ni-Pt films is reliable and stable in 0.5 M H2SO4 up to 200 linear sweep voltammetry cycles, however leaching of Ni occurs in absence of cathodic polarisation. Long-term electrolysis measurements at a HER current of –10 mA/cm2 reveal an increase in potential over time, which is minimised when the Pt content is increased. In 1 M NaOH, the material is stable up to an applied anodic limit of 1.5 V vs. Ag|AgCl although surface passivation takes place at 1.0 V. If the anodic limit does not exceed 0.6 V vs. Ag|AgCl, a fully reversible redox reaction is observed by cyclic voltammetry, with redox charges increasing with Pt content and scan speed. In addition, significantly higher current densities are recorded for mesoporous films compared to dense counterparts. This charge/discharge behaviour of the redox reaction indicates that the mesoporous Ni-Pt films may as well be used as an electrochemical supercapacitor. As a HER catalyst, the material is safely applicable in alkaline media.

To address the severe nitrate contamination of water sources, a Cu/Ni bimetallic composite electrode was successfully prepared via cathodic electrodeposition method. Characterization by scanning electron microscopy, energy-dispersive spectroscopy, and X-ray diffraction confirmed that Cu nanoparticles were successfully deposited on the surface of Ni foam as irregular spherical structures with a diameters of 900 nm. The Cu/Ni electrode was applied as a cathode in nitrate electroreduction experiments, achieving nearly complete removal of nitrate within 60 min compared to a Ni foam electrode (15.0% removal). The improved performance was attributed to the dramatically increased catalytically active sites and the decreased resistance of the electrode, as shown by linear sweep voltammetry and electrochemical impedance spectroscopy analyses. The parameters influencing electrolysis, including current density, Cl− concentration, and solution pH were evaluated. It was concluded that (a) Increasing the current density favored nitrate removal, but reduced the electronic energy utilization efficiency; (b) Cl− presence hindered nitrate removal slightly, but facilitated NH4+-N removal significantly; (c) Acidic conditions were detrimental to nitrate and total nitrogen removal. Additionally, reusability experiments of the Cu/Ni electrode over eight cycles were performed. These indicated that the Cu/Ni electrode possessed excellent stability, maintaining a high removal efficiency of >95.0% over eight cycles. Finally, a possible removal pathway of nitrate electroreduction with the Cu/Ni cathode was proposed.

Cancer stem cells (CSCs) are recognized as an important source of cancers. Surface biomarkers play a critical role for CSCs profiling and also for diagnostic purposes. In this paper, we propose self-assembled supramolecular nanocomposites assisted multiple signal amplification strategy, and successfully apply it in electrochemical detection of an important CSCs biomarker CD44 as well as identification of breast CSCs. A supermolecular composite, consisting of a binding peptide that is able to bind to the target CD44 and a self-assembled diphenylalanine (FF) nanostructure that provides a template for deposition of gold nanoparticles (AuNPs), is elaborately constructed on the surface of an electrode through the linkage of cucurbit[8]urils. In the presence of CD44, this supramolecule is able to provide amplified electrochemical signals from silver-enhancement on AuNPs after target-protection from trypsin-catalyzed digestion. Whereas in the absence of the target, this supramolecular architecture is destroyed, resulting in suppressed signals. Linear sweep voltammetry results present a satisfactory specificity and sensitivity, which also demonstrate a wide linear range with a limit of detection of 2.17 pg/mL toward CD44 protein and a limit of detection of 8 cells/mL toward CD44-positive cancer cells. Therefore, this work provides a promising prospective for further clinic application in the future.

Electroforming of nickel mesh was performed in bath with different concentration of 2-Aminoethanethiol and l -Cysteine to achieve a higher aspect ratio. Although 2-Aminoethanethiol and l -Cysteine have a similar part in their molecules, the optical observation on the cross section of mesh indicated that 2-Aminoethanethiol was an effective additive in improving the aspect ratio of nickel printing mesh whereas l -Cysteine was not. Electrochemical behaviors of 2-Aminoethanethiol and l -Cysteine in the electroforming bath were further evaluated by linear sweep voltammetry (LSV) and galvanostatic measurements using rotating disk electrode (RDE). Both 2-Aminoethanethiol and l -Cysteine could effectively reduce the cathodic polarization and promote deposition of nickel ions. The depolarization effect of 2-Aminoethanethiol which associated with convection is stronger in the high diffusion region than that in the low diffusion region in the present potential region. However, the depolarization effect of l -Cysteine which also associated with the convection is stronger in the low diffusion region than in the high diffusion region unless the potential is negative enough. The different depolarization behaviors under different convection conditions made significant influence on the deposition of nickel ions on the board surface and the internal surface, which finally leads to the high aspect ratio.

Advanced oxidation processes based on the electro-Fenton process are alternative technologies for water and wastewater remediation. In the present work, an activated carbon fiber-supported graphite carbon nitride (g-C3N4/ACF) was prepared by a wet impregnation method, followed by calcination. The results from scanning electron microscopy and X-ray photoelectron spectroscopy demonstrated that the g-C3N4 was successfully supported on the surface of the ACF, leading to a slight decrease in the Brunauer-Emmett-Teller surface area. In the presence of externally added Fe2+ to the electrolyte, the g-C3N4/ACF used as a cathode exhibited a relatively higher activity in the electrochemical degradation of aqueous rhodamine B (RhB) compared to the ACF cathode. The effect of several experimental conditions, such as initial pH, current density, the quantity of Fe2+ added, and the loading amounts of g-C3N4, on the removal of total organic carbon was explored. In the range investigated, the mineralization of RhB had the most rapid progression, with an initial pH of 3.0, current density of 3.0 mA cm−2, initial Fe2+ concentration of 0.25 mM and g-C3N4 load of 0.03 g. The removal efficiency of total organic carbon was ∼91% after 240 min of electrolysis. In addition, the g-C3N4/ACF electrode was stable as evidenced by five successive cyclic tests. On the basis of quantitative measurements of iron (zero-valent iron, ferrous ion, and ferric ion) and qualitative determination of hydroxyl radicals, and with the help of electrochemical characterization in the form of linear sweep voltammetry, cyclic voltammetry and chronoamperometry, it could be concluded that the RhB mineralization proceeded via a surface process. The supported g-C3N4 facilitated the electro-generation and adsorption of H2O2, as well as the regeneration of ferrous ions from surface-adsorbed ferric ions.

Polyvinylpyrrolidone (PVP), as a nitrogen-containing heterocyclic polymer, is a promising candidate for preparation of high performance iodide-based polymer electrolytes for dye-sensitized solar cells (DSSCs). In the present investigation, PVP electrolytes composed of different wt% loadings of potassium iodide and iodine were prepared, thoroughly characterized, and applied to DSSCs. The TiO2 electrode of the solid state DSSCs was optimized (film thickness, dye loading, TiCl4 treatment), to achieve high energy conversion efficiency. Differential scanning calorimetry, Fourier transform infrared spectroscopy, X-ray diffraction, electrochemical impedance spectroscopy, linear sweep voltammetry, and ultraviolet–visible spectroscopy were used to characterize the PVP electrolytes. One-diode model equivalent circuit analysis was applied to DSSCs characteristic curve, in order to calculate the key electrical circuit elements values, determining solar cells efficiency. The maximum energy conversion efficiency attained by the solid state DSSCs under real test conditions was 3.74%, at about 1000 W/m2 irradiation intensity. By in-situ gelation of the PVP electrolytes onto TiO2, an optimal electrode film thickness on the order of 15 μm was achieved, which is very close to the corresponding value usually attained to liquid state DSSCs. The results are satisfactory compared to DSSCs employing liquid state factory available electrolytes, while simultaneously the PVP electrolytes preparation is simple and of low-cost, having great prospects for further optimization.

Fe-Foam (Fe-F) was used as a catalyst in the presence of tripolyphosphate (TPP) electrolyte for electro-Fenton (EF) at circum-neutral pH. Characteristics of Fe-F catalyst were studied by scanning electron microscopy energy dispersive spectroscopy (SEM-EDS) and x-ray photoelectron spectroscopy (XPS). Operational conditions (pH and current) influencing H2O2 electrogeneration in TPP electrolyte at a three-dimensional printed gas diffusion electrode (GDE) were systematically investigated. Moreover, linear sweep voltammetry was used to evaluate the system. Results showed that Fe-F, a three-dimensional porous structure catalyst, was covered with Fe2+, Fe3+ and Fe0. The Fe-F/TPP/EF process allowed an 8.55-fold increase in the rate of phenol degradation (used as a model pollutant), higher pseudo-first-order rate constants (6.22 × 10−2 min−1 against 7.30 × 10−3 min−1), a significantly higher mineralization yield (88.69%% against 30% after 8 h electrolysis) and lower energy consumption (0.10 kWhg−1 against 0.98 kWhg−1), as compared to conventional EF process. The high efficiency in Fe-F/TPP/EF was attributed to the following benefits: i) Fe-F was capable of providing Fe2+ ions by chemical corrosion to form Fe2+-TPP complex, which induced the one-electron transfer activation of O2 leading to formation of OH, ii) chemical Fe2+ regeneration combined with Fe0 corrosion provided an additional source of Fe2+ and compensated the low capacity of Fe3+ reduction at GDE, and iii) both surface-mediated and homogeneous reactions contributed to pollutant degradation. The new proposed Fe-F/TPP/EF process displayed promising properties for wastewater treatment applications.

A new gel polymer electrolyte (GPE) based on ethyl cellulose/poly(vinylidene fluoride) (EC/PVDF) blended polymer was prepared by immersion precipitation phase inversion. The structure of the porous membrane was controlled by the addition of EC. The performance of the membranes with different ratios of EC to PVDF were characterized by X-ray diffraction spectroscopy (XRD), scan electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), linear sweep voltammetry (LSV), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and electrochemical impedance spectroscopy (EIS). The results show that as the ratio of EC to PVDF rose to 3:7 (wt.%), the membrane presented the best thermal stability. The ionic conductivity of this GPE was 1.33 mS cm−1, which was much higher than the PVDF membrane (0.69 mS cm−1) at room temperature. The electrochemical window of this GPE was established to be as high as 5.25 V (vs. Li/Li+). The Li/LiNi0.5Mn1.5O4 coin cell with this GPE displays excellent cyclic stability and rate performance at room temperature compared to PVDF membrane. This suggests that the self-supporting EC/PVDF blended GPE has a high potential for 5 V high-voltage lithium-ion batteries (LIBs).

The polymer-assisted chemical solution (PACS) method was used for the synthesis of La0.8Sr0.2MnO3 (LSM)-based perovskite catalyst network with nanoparticle size of 30–80 nm to enhance oxygen evolution reaction (OER) activity and maintain highly active oxygen reduction reaction (ORR). Samples investigated include the A-site cation deficient (La0.8Sr0.2)0.95MnO3-δ (ALSM) and the A-site cation deficient with the B-site cobalt-doped (La0.8Sr0.2)1-xMn1-xCoxO3-δ (x = 0.05 and 0.1 for LSMC5 and LSMC10, respectively). X-ray diffraction (XRD), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS) aided in physical characterizations. Electrochemical properties were tested in 0.1 M KOH solution by cyclic voltammetry (CV), linear sweep voltammetry (LSV) and electrochemical impedance spectroscopy (EIS). Our results indicate as compared to LSM, the lattice-shrunk ALSM with high oxygen vacancy displays enhanced OER performance, but its inferior ORR activity could be caused by reduced crystallinity. LSMC5 and LSMC10 show lowest total overpotential (0.93 and 0.91 V vs. Ag/AgCl (3.5 M)) with slightly less efficient ORR, despite their superior specific kinetic current density. Oxygen vacancy induces Fermi level upshift and reduced resistivity, while Co-doping increases orbital hybridization and enhances charge transfer. Understanding how the A-site non-stoichiometry and the B-site doping influence the B O covalence is the key to the rational design of perovskite bifunctional oxygen catalysts.

In this research, we synthesized a phenylnicotinonitrile derivative as a new type of additives and studied its effect on the performance of dye-sensitized solar cells by UV–Vis spectroscopy, cyclic voltammetry (CV), linear sweep voltammetry (LSV) and electrochemical impedance spectroscopy (EIS). In comparision with a blank electrolyte (0.35 M lithium iodide, 0.035 M iodine and 0.01 M guanidium thiocyanate in a much less leakage and volatile solvent such as propylene carbonate, PC-liquid), addition of 0.5 M phenylnicotinonitrile derivative caused an increase in the open-circuit potential (Voc) of 209 mV but a decrease in the short current density (Jsc) of 3.36 mA/cm2. The increase could be attributed to the negative shift of the conduction bond of TiO2 semiconductor potential (Voc, ∼34% of the voltage increase) and to the increase of the photo-conversion efficiency (PCE, ∼21% of the efficiency increase). The decrease in Jsc was because of the reduction of dye regeneration and the catalytic activity of the photocathode in electrolyte regeneration. It was shown that the fabricated dye-sensitized solar cells (DSSCs)-based different electrolytes displayed the relative standard deviation (RSD) range of 3.24%–4.36% for six repetitive measurements (n = 6).

A morphology-controlled ion exchange route has been investigated for the preparation of Copper Nitroprusside (CNP) nanosheet. Polyvinylpyrrolidone (PVP) was used as capping agent. The effect of PVP concentration during synthesis was also studied which provides a local control over the morphology of CNP nanosheet to produce an ultrathin CNP nanosheet. Effect of PVP concentration in crystal growth and mechanism has been established. Cyclic voltammogram shows that oxygen evolution reaction (OER) onset potential for CNP nanosheet was found to be 1.45 V with a measured current density of 26 mA/cm2. Linear sweep Voltammetry test has also been conducted to analyze the electrocatalytic OER performance. Anodic slope of Tafel plot establishes higher OER performance of CNP nanosheet than commercial RuO2. CNP nanosheets was found to be cheap and efficient eletrocatalyst for water splitting reaction. Voltammetric current density has also been expressed as a function of average thickness of nanosheets.

A coconut-shell-based carbon was activated with KOH and three methods of ammonia modification were used to prepare nitrogen-containing activated carbon of high surface area. Thus, a cost-effective, scalable, and metal-free electrocatalyst was developed for use in oxygen reduction reaction (ORR). Elemental analysis, X-ray photoelectron spectroscopy (XPS), Scanning electron microscopy (SEM) and nitrogen adsorption have been used to analyze the physicochemical properties of activated carbons. The electrocatalytic performance of activated carbons was investigated with respect to ORR using cyclic voltammetry and linear sweep voltammetry in an alkaline electrolyte. The results indicate that the species distribution of nitrogen-containing groups was significantly affected by the method and temperature of ammonia modification. These factors consequently determined the electrocatalytic performance of the modified activated carbons. When the nitrogen-containing activated carbon was prepared by methods I and II at 950 °C, it exhibited an electrocatalytic activity toward ORR that was comparable to that of commercial 20% Pt/C catalyst in terms of onset potential and limiting current density. Moreover, they catalyzed ORR approximately in a four-electron pathway and showed good tolerance toward methanol crossover. In addition, we investigated the influence of various nitrogen-containing species on the electrocatalytic performance.

Carbon nanoparticles (CNPs) derived from candle soot were used to prepare an efficient electrode of a microbial fuel cell (MFC). The candle soot were deposited on an ultrafine stainless steel (SS) wire disk, and the SS disk-supported CNPs were directly used as the electrodes. The physico-electro-chemical characterization tests showed the prepared electrode materials to be hierarchically porous, graphitic, and mechanically and electrochemically stable. The polarization studies using linear sweep voltammetry analysis revealed the maximum open circuit potential, power and current densities of the fabricated MFC to be 0.68 ± 0.03 V, 1650 ± 50 mW/m2 and 7135 ± 110 mA/m2 respectively. The method of preparation for the soot-derived CNP-based electrode material is simple, cost-effective, reproducible, and scalable, and the fabricated MFC has potential for producing high bioenergy.

Electrochemical studies have been conducted at copper microelectrodes (125, 50, and 25 μm in diameter) immersed in aqueous 0.5 M NaCl. Cyclic and linear sweep voltammetry were used to explore the corrosion of copper in chloride media. Cyclic voltammetry revealed the reversible Cu(I)/Cu(0) potential at approximately −0.11 V vs. SCE associated with the formation of a dense CuCl blocking layer (confirmed by in situ Raman and fluorescence measurements). Although continuous dissolution of Cu(I) occurs, only an increase in the driving potential into the region of the Cu(II)/Cu(I) potential at approximately +0.14 V vs. SCE started more rapid and stochastic dissolution/corrosion processes. The corrosion process is demonstrated to be linked to two distinct mechanisms based on (A) slow molecular dissolution and (B) fast colloidal dissolution. A polymer of intrinsic microporosity (PIM-EA-TB) is employed to suppress colloidal processes to reveal the underlying molecular processes.

Storage devices have been widely reported to satisfy the increase needs in the electronic and transportation areas. The easy access of the electrolyte ions to the surface of the electrodes of carbon nanomaterials is a challenge to be overcome in supercapacitors, especially in the case of ionic liquid electrolytes. Herein, the study of four different ionic liquids (IL) to select the one that exhibits better electrochemical properties in the presence of GO has been accomplished. Among the prepared IL composites, the one with [SET3][TFSI] showed an increase in the conductivity values and an electrochemical stability of over 3.5 V as measured by linear sweep voltammetry. The viscosity of composite [SET3][TFSI]-GO as a function of different concentrations of GO was discussed considering its effect on the conductivity mechanism. Furthermore, supercapacitors based on neat IL and IL-GO 0.1 wt% with reduced graphene oxide (rGO) were investigated. The best results obtained by cyclic voltammetry of the supercapacitor rGO/[SET3][TFSI]/rGO showed a capacitance value of 95.8 F g−1, whereas the supercapacitor rGO/[SET3][TFSI]-GO/rGO exhibited a capacitance of 125.3 F g−1, both at 5 mV s−1, working in a 2.5 V range; which demonstrates an increase of 31% in capacitance because of the presence of GO in the IL. TEM images indicated that the composite electrolyte increases the compatibility of the ionic liquid electrolyte with the rGO electrode, probably favoring the accessibility of the electrolyte ions to the electrode surface.

A major portion of the existing literature on TiO2 nanotubes modified by CdS and CdSe report an enhanced photoelectrochemical (PEC) performance using electrolytes with inorganic sacrificial electron donors where a dominant sulfite oxidation occurs. In this study, we distinguish the PEC performance arising entirely from water splitting to that originated by sulfite oxidation in the TiO2 nanotube system modified by CdS/CdSe nanoparticle depositions. The photocurrent density measured under the AM1.5G simulated spectra, 1 sun (100 mWcm−2) intensity for the TiO2 nanotubes modified by CdS/CdSe nanoparticles and using an aqueous alkaline electrolyte (1 M NaOH) was observed to be 0.92 mAcm−2 at 1.23 V vs. RHE which was 8-fold lower than in the case for sulfite oxidation (Jph/SO = 7.4 mAcm−2 at 1.23 V vs. RHE) using an Na2S/Na2SO3 aqueous electrolyte. A maximum STH efficiency of 0.71% and water splitting efficiency of 12.4% was determined for water oxidation using an aqueous alkaline electrolyte. To rationalize such device efficiency, we propose that the ‘water splitting efficiency’ parameter is much more meaningful since it correlates the PEC activity specifically to water splitting and not to other pathways that produce an artificially enhanced photocurrent through the use of sacrificial reagents. The incident photon-to-current conversion efficiency spectrum measured at 1.23 V (vs. RHE) bias for the TiO2 photoanodes modified by CdS/CdSe nanoparticles revealed that the current conversion efficiency is lower (∼17% or less) when absorption occurs solely from the external CdSe layers indicating higher recombination during charge transport. The increase of dark current observed in the linear sweep voltammetry plots for the voltage range of −0.25 V to +0.15 V vs. RHE was attributed to anodic dissolution of the photoanodes in aqueous electrolytes containing no sacrificial reagents. The photocurrents and onset potentials for the CdS/CdSe modified TiO2 photoanodes improved under acidic conditions showing a slightly increased PEC activity and faster reaction kinetics.

Hydrogen is the next-generation clean and ecofriendly alternative energy source. Its generation through water splitting is promising for sustainable production. The advancement of highly effective, stable, and profitable materials are the key challenges in catalyst design. In this direction, a novel single-step fabrication strategy employing micro-indented-mechanically-engineered (MIME) multinary (Ni-Fe-Mo-Cu) bare metallic material is an intriguing attempt to develop a highly efficient electrocatalytic oxygen evolution reaction (OER) at lower overpotential. This novel idea is based on applying compressive load through a rolling mill to generate micro-indents that act as active sites for the hydroxyl ions for accelerating OER. The Linear sweep voltammetry (LSV) curves showed 10 mA cm−2 could be generated employing the MIME electrode of 1000 N load at a lower overpotential. Electrochemical Impedance Spectroscopy (EIS) revealed that the lowest polarization resistance (Rp) was obtained at the same load. The electrocatalytic activity of the electrode was sustained by the formation of the porous oxide film which eventually improved the overall electrochemical surface-area of the electroactive film composed of respective alloying elements confirmed by comprehensive X-ray photoelectron spectroscopy (XPS) analysis.

The two-dimensional Saul’yev method of simulating processes at an ultramicrodisk electrode is compared with the fully implicit backward differentiation method started with a few backward implicit steps, and an alternating direction implicitmethod. 2D Saul’yev is convenient to program and although it is significantlyslower in execution than the other two methods, it still executes in reasonabletime, and yields equally good results with a suitable choice of discrete intervals,and despite its inherent propagation problem, and a certain restriction in therelationship of the spatial and temporal intervals. Saul’yev was implemented forthe diffusion limited potential step experiment, as well as linear sweepjvoltammetry for a reversible system. The two-dimensional Saul’yev method of simulating processes at an ultramicrodisk electrode iscompared with the fully implicit backward differentiation method started with a few backward implicitsteps, and an alternating direction implicit method. 2D Saul’yev is convenient to program and although itis significantly slower in execution than the other two methods, it still executes in reasonable time, andyields equally good results with a suitable choice of discrete intervals, and despite its inherentpropagation problem, and a certain restriction in the relationship of the spatial and temporal intervals.Saul’yev was implemented for the diffusion limited potential step experiment, as well as linear sweepvoltammetry for a reversible system.

This work assesses the role of the operational conditions upon the electro-activation of persulfate (electro-PS) using Ti/IrO2 Ta2O5 electrode for the decolorization of anthraquinone azo dye Disperse Blue 3 (DB3). The studied variables include current density (j) (5–80 mA cm−2), persulfate concentration based on the stoichiometric dose for complete DB3 mineralization (20–100%), temperature (30–90 °C) and pH (3–12) as well as the influence of dissolved oxygen. The persulfate activation from cathodic reduction was confirmed by linear sweep voltammetry (LSV). The increase in j enhanced the PS decomposition and, consequently, decolorization efficiency, because of the greater production of sulfate radicals (SO4•−). Besides, the combination of electro-PS with thermal activation resulted in a synergistic effect upon the DB3 mineralization. In the range 30–70 °C, electro-PS led to a significantly higher TOC conversion (above 60% at 40 mA cm−2) than sole heat-activated PS. This difference steeply decreased as temperature increases, achieving similar TOC conversion at 90 °C after 60 min.

Co-electrolysis of water and carbon dioxide in molten carbonates is nowadays a key issue in MCEC (molten carbonate electrolysis cell) and, reversely, for a better understanding of MCFC (molten carbonate fuel cell). The products of water and carbon dioxide reduction are the fuels that might be used in MCFC or other energy devices. The present study is dedicated to a thorough electrochemical investigation by voltammetric techniques (Cyclic Voltammetry CV or Linear Sweep Voltammetry LSV) at a Pt electrode of such fuels in Li2CO3-K2CO3 eutectic, under varied atmosphere conditions, including partial pressures of H2O, CO2, H2 and Ar at 650°C. The conditions of formation of soluble and/or adsorbed H2 and CO are established together with qualitative thermodynamics information on the redox systems involved. C is only detected in very specific conditions. Knowing that hydroxides, produced in the conditions of MCEC and MCFC, have a significant role on the operation of such devices, an electrochemical analysis (CV and impedance measurements) of the effect of added amounts of hydroxides is developed for the first time, showing the enhancement of oxidation currents and the progressive increase in electrolyte conductivity.

Developing inexpensive, earth abundant materials for electrocatalytic and photoelectrochemical water splitting is critical to the decarburization of our energy system. Aerosol-assisted chemical vapor deposition (AACVD) is a potentially scalable, one-step synthesis technique that can produce large area, homogenous edge-aligned films of transition metal dichalcogenides including MoS2. Herein, we report a hydrogen evolution reaction (HER) study on such electrode films under acidic conditions. Using iR compensated near-steady state DC current-potential measurements and linear sweep voltammetry, the HER onset potential is recorded at −175 mV vs. RHE (current density 0.1 mA cm−2), while a current density of 10 mA cm−2 per nominal area is reached at an overpotential of −430 mV vs. RHE. A Tafel slope of 113 mV dec−1 suggests the existence of increased edge-active sites on the surface of 2H-MoS2. The electrodes offered high stability over 5000 cycles, which continued to improve with cycling, with the current density at −350 mV improved by a factor exceeding 20 between the 1st and 5000th cycle. X-ray photoelectron spectroscopy, contact angle measurements and electrochemical impedance spectroscopy were employed to provide thorough insights on the changes in the intrinsic properties of the material, which led to the observed HER activity enhancement with cycling. It is shown that a reduction in the surface oxide layer and increased electrowetting are the reasons for the improved performance. Electrodes of differing thicknesses were prepared and their performance was compared in association with the surface morphology. The best performing electrode had the lowest mass loading of MoS2, which is attributed to improved faradaic efficiency through the resistive 2H-MoS2 electrode.