Journal of Electroanalytical Chemistry最新文献

Transition metal dichalcogenides (TMDs) are potential candidates for electrocatalytic applications due to their unique structures and intrinsic properties. In this work, the systematic synthesis of conducting polymer-templated and nonnoble metal-doped MoSe₂ hybrids was carried out using a facile hydrothermal method. Integrating conductive polyaniline, as a conductive polymer, with MoSe₂ nanosheets (MoSe₂@PANI) as well as transition metal (Co, Ni or Fe) doping provided more active sites for both H⁺ and OH^– adsorption, resulting in enhanced hydrogen and oxygen evolution performance. The Co-doped MoSe₂@PANI hybrid catalyst exhibited enhanced bifunctional electrocatalytic activity for the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER) in alkaline electrolytes, where Co-doping as well as polyaniline addition played key roles in boosting the HER/OER activity. As a result, the Co-doped MoSe₂@PANI catalyst exhibited overpotentials of 196 mV and 385 mV at a current density of 10 mA cm⁻² for the HER and OER, respectively. When Co-doped MoSe₂@PANI was applied as a bifunctional electrocatalyst for overall water splitting, a potential of 1.82 V was needed to achieve a current density of 10 mA cm⁻². Moreover, the Co-doped MoSe₂@PANI catalyst displayed good stability for long-term cycling. This work provides new insight into the design of metal-doped TMD/conducting polymer-based materials for electrocatalytic applications, including water electrolysis.

Few research has investigated the problem of regeneration of activated carbon once it has been saturated by organic and inorganic contaminants. Among the regeneration methods, electrochemical technology is one of the most advanced, demonstrating its effectiveness in pilot-plant scale experiments using samples obtained from drinking water treatment plants. In the present study, the optimization of a parallel plate electrochemical reactor with a capacity of 15 kg of activated carbon, has been achieved regarding the electrolyte concentration and flow rate. A regeneration efficiency of approximately 90% was achieved with a 0.25 M H₂SO₄ concentration, while lower concentrations resulted in a voltage exceeding the acceptable limits for this type of installation. In addition, higher flow rates imply a higher recovery of the porous texture of the regenerated activated carbon. This is, to the best of our knowledge, the first report where these two experimental variables are optimized in a pilot-scale process with real saturated activated carbon samples with different types of pollutants adsorbed in the activated carbon.

Graphene/polyaniline nanotube/ZIF-67 nanocages (G/PANI-NT/Z) composites were successfully prepared in a co-precipitation manner and used as electrode material for supercapacitor application. ZIF-67 nanocages, including cube and hexapod, were designed via a simple and fast one-step Cu₂O template etching route. The properties of the as-synthesized nanoparticles were perused by N₂ adsorption–desorption, X-ray diffraction (XRD), field emission scanning electron microscope (FESEM), and electrochemical manners. In particular, the super-capacitive performance of the synthesized materials was perused by changing the morphology of the nanostructures. Results represent that the as-synthesized ZIF-67 nanocages maintain the shape and size of the Cu₂O templates with a hollow, which depicts various capacitive demeanors. Amongst, the two morphologies, the G/PANI-NT/Z-hexapod (h) composite has a larger specific capacitance of 4400 mF g⁻¹, while G/PANI-NT/Z-cubic (c) has a lower one of 3630 mF g⁻¹ at 10 mA g⁻¹ current density. This is mainly due to the presence of ZIF-67 nanocages with hexapod morphology and a larger surface area of 73.58 m²/g in the G/PANI-NT/Z-h composite, which leads to fast interfacial electron transfer and an increase in the diffusion rate of electrolyte ions for higher power density. This demonstrates G/PANI-NT/Z-h electrode is promising for applications in renewable energy storage.

Several triphenylamine end capped to substituted central naphthalenetetracarboxylic diimide based four donor - acceptor - donor type electro-active monomers (BRTPANDI, CNTPANDI, PHTPANDI, NPYTPANDI) were designed and developed to explore the effect of substituent on the formation of electro-polymers and subsequent the chromic effect of prepared films on the conductive surface. Initially, with the help of density functional theory (DFT) studies, it was observed that HOMO was located over triphenylamine unit, responsible electro-polymerization process upon oxidation, LUMO was residing on the central naphthalene core, and all substituents were not coplanar with naphthalene moiety. Also, the band gap energy was gradually decreased with the effect of strong electron withdrawing substituents on NDI core. In three electrode configuration, reversible multiple colour changes of brown to deep blue by applying voltage 0 to 1.1 V and also brown to deep pink with the voltage change of 0 to −2 V were impressively investigated with relatively good response times, optical contrast, switching stabilities, and coloration efficiencies. Polymer made of CNTPANDI might be switched upto 1200 cycles with the optimum colouration efficiency 560 cm²/C in the anodic process and 300 cycles for the cathodic process in a three electrodes configuration. Proto type devices made of p-CNTPANDI demonstrated the electrochromism operated at a potential range of 0 to 2.2 V. Besides, the device exhibited the EC memory in open-circuit condition with 50% retention of its coloured state until 27 min. The long EC memory as well as high colouration efficiency compared to other TPA based conjugated polymers suggested the potentiality of those polymer films as a power-efficient EC material for modern display applications.

In this study, the effects of poly(oxy-1,2-ethanediyl), alpha-(4-nonylphenyl)-omega-hydroxy-,branched (ANP) under various concentrations on the Cu-electrodeposition on the brass surface were investigated. The leveling, grain refining, and brightening agent effects have been identified for the used ANP additive. In addition, the Cu-electrodeposits morphology was studied by Scanning Electron Microscopy (SEM) coupled with Energy dispersive X-ray analysis (EDS) and Atomic Force Microscopy (AFM). The cyclic voltammetry technique, the quantum chemical calculations, and molecular dynamics (MD) simulations were also used to explain the Cu-electrodeposition mechanism. Finally, electrochemical measurements were employed to study the ANP effect on the Cu-electrodeposit resistance in a 3.5 wt% NaCl medium. The cyclic voltammetry demonstrated that the studied system is irreversible and that the kinetics of the Cu-electrodeposition reaction are controlled by diffusion. In addition, the SEM/EDS and AFM results revealed that the ANP addition increases the Cu-electrodeposit with an improvement in its roughness degree and crystallite size. In the same context, the quantum chemical calculations and molecular dynamics (MD) simulations suggested that ANP may be strongly adsorbed on the brass and Cu-electrodeposit surfaces. Toward the end, the electrochemical measurements results indicated that the polarization resistance of the Cu-deposit increases with the presence of ANP in the copper bath, demonstrating its good corrosion resistance in marine medium.

Gold nanoclusters (AuNCs), as a category of promising electrochemiluminescence (ECL) emitter, hold great potential for sensing applications. However, its application is still restricted by the relatively low ECL quantum yield and difficult to purification. In this work, AuNCs were confined in a soft chitosan (CS) nanogel matrix (AuNCs@CS) with good biocompatibility via a facile one-pot approach. The as-fabricated AuNCs@CS nanogels showed 2.4-fold ECL intensity relative to that of bare AuNCs without chitosan. The ECL enhancement was attributed to the increased percentage of Au(0) in AuNCs@CS nanogels, the confinement effect of chitosan nanogels, as well as chitosan as a polymer could reduce the diffusion of the radicals and prolong the excited state lifetime of AuNCs in ECL reaction. Moreover, the obtained AuNCs@CS nanogels are stable and easy to be purified by centrifugation. On this basis, a label-free ECL immunosensor for ultrasensitive detection of aflatoxin B1 (AFB1) was developed by using AuNCs@CS nanogels modified fluorine doped tin oxide (FTO) electrode as a sensing interface. The linear range of the proposed immunosensor for AFB1 detection was 3.16 × 10^-14 to 3.16 × 10^-12 g/mL with a detection limit of 9.3 × 10^-15 g/mL, which was at least one order of magnitude lower than the reported ECL biosensor of AFB1. The proposed strategy may be used for the determination of other toxins in the Aflatoxin family if corresponding antibodies are available, which is of great significance for the quality control of Chinese herbal medicine and food safety.

Sodium-ion batteries (SIBs) have drawn evolutionary attention due to the urgent requirements for renewable energy storage. Unfortunately, the cycle stability and rate capability of promising SnO₂ materials are far from satisfactory. Herein, enhanced Na-ion storage via creating smooth ion transportation pathways in a modified heterostructure has been originally demonstrated. The tuned composite of uniformly dispersed SnO₂ particles anchored on the surface of graphene nanosheets was prepared via a facile hydrothermal treatment with the help of iodine. Inspiringly, an anticipated Na-ion storage can be successfully achieved, with reversible Na-ion storage of 486.1 mA h g⁻¹ at 50 mA g⁻¹ and rate capability of 343.8 mA h g⁻¹ even at 800 mA g⁻¹. The exceptional electrochemical property profited from the synergistic effect of the heterostructure with plentiful ion transportation pathways for fast Na-ion diffusion. This work opens a practical opportunity for the design of next-generation rechargeable batteries in energy storage.

FeMoO₄ is a potential anode material for Li-ion batteries due to its high theoretical specific capacity. The factors that restrict the application of FeMoO₄ are the low specific surface area of the material and poor cycle stability caused by the huge volume change during the cycling process of lithium ion insertion and extraction. In this work, N-doped porous carbon was synthesized and composited with FeMoO₄ by a hydrothermal method. The large specific surface area provided by the porous structure can enable sufficient contact of ions/electrons with active sites, thereby enhancing the lithium storage performance and buffering the volume change during lithiation/delithiation, leading to a high cycling stability of the material. After 200 cycles at a current density of 300 mA g⁻¹, the discharge specific capacity of the composite can reach up to 1291.4 mA h g⁻¹.

Lithium-ion batteries (LIBs) are widely used due to their high capacity, high safety, and low cost. The anode material exhibits significant volume changes and subsequent reversible capacity decay during the lithiation/delithiation process, therefore, the performance of lithium-ion batteries is determined by the anode material. In this work, dendritic Fe₂O₃ single crystal with different precursor concentrations was prepared by hydrothermal method. The composition and microstructure of the samples were analyzed and tested using X-ray diffraction, scanning electron microscopy, and transmission electron microscopy techniques. The electrochemical performance was tested using cyclic voltage measurement and electrical impedance spectroscopy. The leaves of dendritic Fe₂O₃ were too small when the iron source concentration was too low to provide enough Fe³⁺, and excessive Fe³⁺ led to the leaves of dendritic Fe₂O₃ being too thick. The most suitable branch size and thickness of dendritic Fe₂O₃ single crystals were grown for 0.007 mol/l Fe³⁺ concentration (sample L4), and its electrode showed the best electrochemical performance. The sample L4 has a capacity of up to 734 mAh∙g⁻¹ for 200 cycles at 100 mA∙g⁻¹, and has a specific capacity retention rate of 95.4% after high current 3000 mA∙g⁻¹. This work is believed to facilitate understanding single crystal growth mechanisms and promote the development of high-performance lithium-ion batteries.

Electrochemical evaluations of the commercially available inhibitor Trasar Trac102 were carried out under static and hydrodynamic conditions on API 5L X65 steel immersed in NaCl 3% wt. By Electrochemical Impedance Spectroscopy (EIS) techniques, obtaining the best efficiency of 95.4% under static conditions at 20 ppm. It was detected by rotating cylinder electrode that as the revolutions per minute of 100, 500 and 1000 rpm were increased, the inhibition efficiency tended to decrease as a result of the adsorption–desorption process of the organic molecules by the rotation rate. The results showed that the adsorption type of Trasar Trac102 on API 5L X65 steel in NaCl 3% wt was to form a monolayer on the metal surface according to the model fit with Langmuir isotherm. Scanning Electron Microscopy (SEM) was used for surface characterization, which shows a great difference in the target systems with corrosion products as a result of the deterioration caused by the corrosive medium and in the presence of the inhibitor. The results of the chemical analysis (EDX) show a significant decrease of oxygen in the presence of the inhibitor, suggesting that Trasar Trac102 is adsorbed directly on the steel. Dispersion-Corrected Density Functional Theory (DFT) calculations were used to characterize the interactions between the inhibitor components and the steel surface by a cluster approach. Mostly, chemisorption was explained by bonds established between oxygen atoms of inhibitor components and iron ones of the steel surface. Due to their free binding energies computed, metasilicate and mercaptobenzothiazol are expected to interact strongly and to adsorb spontaneously on the steel surface. Also, metasilicate is the component that obtained the largest charge transference to iron cluster.