Journal of Solid State Electrochemistry最新文献

Self-terminated Pt electrodeposition on Au occurs at large negative overpotentials where hydrogen adsorption H_ads inhibits the coordination of PtCl₄²⁻ and/or PtCl₃(H₂O)⁻ to the electrode surface in chloride-supported electrolytes. Potential control can be used to toggle the H_ads coverage to enable multicycle Pt deposition. Specifically, the applied potential is stepped between + 0.4 V_SSCE and − 0.8 V_SSCE, transiting the regime of overpotential activated Pt electrodeposition. The amount of metal deposited depends on capacitive charging delays associated with the double layer and competitive Cl⁻, H, and PtCl_4-x(H₂O)_x^−2+x adsorption. In addition, significant potential deviations arise from ohmic losses that are a function of the supporting electrolyte, cell geometry, and PtCl_4-x(H₂O)_x^−2+x concentration. Taken in combination, the delay in reaching the growth termination potential leads to additional metal deposition and roughening per pulse cycle. Experiments with a parallel plate cell enable the resistive component of the ohmic losses to be specified by the separation between the working and reference electrodes. During multicycle deposition, the H_upd pseudo-capacitance associated with Pt surface sites leads to further RC time constant delays and roughening. The transition to three-dimensional growth leads to low-density films as clearly evidenced after 50 deposition cycles. The difficulties with the pulsed potential scheme can be circumvented, or at least minimized, by using electrolyte exchange to introduce the PtCl_4-x(H₂O)_x^−2+x reactant at a fixed potential, i.e., − 0.8 V_SSCE into the weakly acidic electrolyte. The resulting fractional Pt coverage per cycle is a monotonic function of K₂PtCl₄ concentration and ranged from 0.2 to almost a complete monolayer reflecting the competition between PtCl_4-x(H₂O)_x^−2+x reduction and adsorption of the blocking H_ads layer.

The present research provides a newly developed method that aims at versatile, rapid, portable, and low-cost instrumental protocol for colorimetric analysis of waters, polluted by dyes, through the use of a smartphone and app that detects and represents the RGB (red, green, and blue) color model. The calibration of the method is based on RGB values obtained by capturing images of colored solutions with known concentrations. The method was spectrophotometrically validated by analyzing the same samples, reaching more than 95% of accuracy. The utilization of this smartphone-based method for colorimetric analysis was proposed to follow, for the first time, the electrochemical treatment of different water matrices (400 mL of synthetic and real) with substantial organic and salts content (50 mg L⁻¹ of methylene blue in 0.1 mol L⁻¹ Na₂SO₄) using boron-doped diamond (BDD) anode by applying current densities (j) of 15, 30, and 60 mA cm⁻². Discoloration results (which were achieved with this novel smart water security solution) clearly showed that significant removal efficiencies were achieved in 2 h, depending on the j, when synthetic and real effluents were used. A key role was played by the sulfates in solution which were electroconverted to persulfates via reaction with ^•OH produced at BDD surface, enhancing the oxidation power of the electrochemical treatment. Then, the procedure presented here obtained a high level of confidence representing great support for scientific laboratories as an alternative that can replace the use of expensive spectrophotometers.

Laser-induced graphene (LIG) electrodes have shown promise for electroanalytical applications because of their unique properties, precise thickness, and morphology control. This study optimized the fabrication parameters of LIG electrodes on the thinnest commercial polyimide tapes by employing response surface methodology (RSM) combined with a randomized Box-Behnken experimental design (BBD). Kapton polyimide (PI) tapes were laser-engraved to create a three-electrode electrochemical system. Laser power, engraving speed, and laser distance were evaluated using the heterogeneous kinetic constant (k°) as the response variable. Optimal conditions were identified as 1.925 W power, 2729 mm/min speed, and 7.6 mm focal distance, yielding peak differences of 93 mV, electric double-layer capacitance of 1.95 µF, anodic peak current of 60.1 µA, and k° of 0.0074 cm/s. Raman spectroscopy of the LIG showed peaks at ~ 1350 cm⁻¹ (D band), ~ 1580 cm⁻¹ (G band), and ~ 2700 cm⁻¹ (2D band), indicating disordered and ordered graphitic structures. XRD analysis confirmed the presence of amorphous adhesive material and partial restoration of the graphene structure, with peaks corresponding to reduced graphene oxide (rGO) and graphitic planes. Reproducibility and repeatability studies via cyclic voltammetry (CV) in Fe(CN)₆³⁻/⁴⁻ solution showed minor variations in peak currents and potentials, with RSD values of 2.64% for anodic and 2.26% for cathodic currents. Stability over 120 cycles showed an RSD of 1.57% for potentials and 3.53% for currents, with long-term tests over 20 days revealing a 14.5% and 15.9% decrease in anodic and cathodic peak currents, respectively. Optimized LIG electrodes were used to determine catechol (CC) and ascorbic acid (AA) using differential pulse voltammetry (DPV). CC determination yielded a linear range of 2 to 400 µM with a limit of detection (LOD) of 0.37 µM and a limit of quantification (LOQ) of 1.25 µM. AA determination resulted in a linear range of 20–4000 µM with an LOD of 4.26 µM and an LOQ of 14.21 µM. These results highlight the excellent performance of the optimized LIG electrodes in electroanalytical applications.

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This study describes the development and characterization of an electrochemical sensor based on gold nanoparticles (AuNPs) immobilized on a screen-printed carbon electrode (SPCE) supported by polyethylene terephthalate (PET) for ciprofloxacin (CPX) detection. The SPCE-AuNPs sensor was fabricated using optimized carbonaceous material-based inks for the working and counter electrodes, while silver/silver chloride ink was employed for the quasi-reference electrode. Electrochemical characterization revealed a significant 223% increase in CPX oxidation current intensity compared to the unmodified SPCE electrode. Electrochemical impedance spectroscopy (EIS) confirmed this improvement, showing a decrease in charge transfer resistance (Rct) from 0.225 kΩ for SPCE to 0.125 kΩ for SPCE-AuNPs. Under optimized conditions utilizing differential pulse voltammetry (DPV), the sensor exhibited a linear range of 0.4 to 88.0 μmol L⁻¹, a limit of detection of 0.12 μmol L⁻¹, and a limit of quantification of 0.4 μmol L⁻¹. The developed method was applied to determine CPX in water and pharmaceutical formulation samples, achieving excellent recovery values ranging from 96 to 104%.

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In this work, a simple and efficient hydrothermal synthesis route for CuS and CuS/C-150 is presented, overcoming the limitations of traditional methods by using a single-step synthesis that allows more efficient and scalable process. This method also provides a more detailed study of the mechanisms between the material/electrolyte interface through electrochemical impedance spectroscopy. Scanning electron microscopy analyses revealed the morphological formation of microspheres and microsheets under the synthesis conditions. The method and synthesis conditions led to the formation of CuS in the covellite form (JCPDS nº 06–0646), which was confirmed via X-ray diffraction. A decrease in the intensity of the peaks in the CuS/C-150 diffractogram was observed, characteristic of amorphous material. Cyclic voltammetry revealed redox peaks characteristic of CuS and CuS/C-150 materials, and the specific capacity values of CuS and CuS/C-150 were measured by galvanostatic charge–discharge, yielding 168.8 and 121.9 C.g⁻¹, respectively. These values indicate that these materials are good charge storage. For cyclic stability (5 mA.cm⁻²), CuS/C-150 retained 74.1% after 200 cycles. Electrochemical impedance spectroscopy analysis indicated that the resistances were negligible for both solution and charge transfer. Through complex calculations via impedance spectroscopy, the materials obtained relaxation time constants (τ₀) of approximately 2.30 s, and at the intercept of the |Q/S| =|P/S|, 70% curves were obtained. Therefore, the electrochemical results were satisfactory and confirmed that the materials are promising battery-type electrodes and that the hydrothermal route is viable and effective for obtaining the studied materials.

Porous anodic aluminum oxide (AAO) layers have been obtained by two-step anodization of high-purity Al in two types of acid mixtures, i.e., in H₂C₂O₄–H₃PO₄ and, for the first time, in H₂SO₄–H₃PO₄ systems. The kinetics of oxide formation was examined by monitoring the current vs. time curves while the morphology of the resulting layers was carefully verified by scanning electron microscopy (SEM). A special emphasis was put on establishing correlations between electrolyte composition, the kinetics and effectiveness of oxide growth, and the morphological features of AAO layers (pore and cell diameter, porosity), as well as pore arrangement. It was confirmed that the addition of H₃PO₄ to both H₂C₂O₄ and H₂SO₄ electrolytes results in a significant decrease in oxide growth rate, and worsening of pore arrangement, while the values of pore diameter and interpore distance are much less affected. Moreover, the presence of a small amount of phosphoric acid in the reaction mixture allowed for a noticeable increase in pore ordering if anodization was carried out beyond the self-ordering regime, or performing controlled anodization even at voltages at which the burning phenomenon is typically observed. It is strongly believed that manipulating the electrolyte composition by adding another acid may provide another degree of freedom to control the morphology of the resulting nanostructured alumina layers.

As a class of two-dimensional transition metal compounds, MXene has become the most potential alternative electrode materials because of its fascinating properties. In this contribution, the electrochemical properties of Zr₂N with O and S groups for K-ion battery are explored. The O and S functional groups have high electronegativity and high affinity with K-ion; the results show that the most stable adsorption site of Zr₂NO₂ and Zr₂NS₂ models is on the bottom Zr atom; with regard to the Zr₂N model, it is located at above the N atom; and the corresponding adsorption energy on the surface of Zr₂NO₂ and Zr₂NS₂ models is far less than that Zr₂N model. The differential charge density map and atomic population indicated obvious electron transfer between the adsorbed atom and monolayer, which proved that there is some chemisorption. With regard to the electrochemical performance, K-ion has low open-circuit voltage and high theoretical specific capacity on Zr₂N, Zr₂NO₂, and Zr₂NS₂ models, and the migration barrier is smaller than that of common two-dimensional materials. A series of results suggest that Zr₂N, Zr₂NO₂, and Zr₂NS₂ can be applied as potential anode materials for K-ion batteries.

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The demand for high capacity and high energy density lithium-ion batteries (LIBs) has drastically increased nowadays. One way of meeting that rising demand is to design LIBs with thicker electrodes. Increasing electrode thickness can enhance the energy density of LIBs at the cell level by reducing the ratio of inactive materials in the cell. However, after a certain value of electrode thickness, the rate of energy density increase becomes slower. On the other hand, the impact of associated limitations becomes stronger, reducing the practical applicability of LIBs with thicker electrodes. Hence, an optimum value of thickness is of utmost importance for the practicability of thicker electrode design. In this paper, both the cathode thickness and the anode thickness of an NCM LIB cell were optimized by applying response surface methodology (RSM) with a Box-Behnken design (BBD) to maximize the energy density. Moreover, the influence of electrode porosity, together with the interaction of porosity with cathode and anode thickness, was incorporated into the optimization. A full factorial design of 3-level, 3-factor was used to generate 15 simulation conditions in accordance with the design of experiment (DoE) achieved through BBD. Then, those conditions were used to achieve 15 responses by simulating a reduced-order electrochemical model. Finally, the statistical technique analysis of variance (ANOVA) was used to analyze and validate the results of RSM. The results show that the RSM-BBD optimization method, coupled with ANOVA, has successfully optimized the thicknesses of both positive and negative electrodes for maximum energy density, despite the nonlinearity of the electrochemical system. The findings suggest an optimized cathode thickness of 401.56 µm and anode thickness of 186.36 µm for a maximum energy density of 292.22 of an NCM LIB cell, while electrode porosity is preferred to be 0.2.

Ethylene glycol solutions can cause severe corrosion in magnesium alloys, leading to safety and stability concerns. The addition of corrosion inhibitors to the environment is a simple and effective protective measure. This study introduces a compound corrosion inhibitor that combines inorganic and organic components, providing resistance to salts, high temperatures, and environmental factors. The corrosion inhibition of AZ91D magnesium alloy using a sodium silicate/triethanolamine compound inhibitor in 50% glycol coolant was investigated through electrochemical analysis, morphology characterization, and weight loss analysis. The results demonstrated that the sodium silicate/triethanolamine inhibitor effectively prevented corrosion of AZ91D magnesium alloy in 50% ethylene glycol, achieving a maximum inhibition efficiency of 96.4% with 2 g/L sodium silicate and 3 mL/L triethanolamine. The inhibitor exhibited continued effectiveness at elevated temperatures and showed minimal impact from external ions, providing strong protection for AZ91D magnesium alloy in glycol coolant. The outstanding performance can be attributed to the synergistic interaction of triethanolamine and sodium silicate, which form a protective film on the alloy’s surface. This compound inhibitor exhibits promising potential for safeguarding AZ91D magnesium alloy in similar environments. Furthermore, the proposed mechanism elucidates how the sodium silicate/triethanolamine mixture mitigates galvanic corrosion in the AZ91D magnesium alloy.