Journal of Solid State Electrochemistry最新文献

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.

Solid oxide fuel cells (SOFCs), efficient and clean energy converters, typically use hydrogen, which has low energy density and transport challenges. Methanol (CH₃OH), with its high energy density and ease of storage, is an ideal alternative. This study uses a 3D multiphysics model in COMSOL to simulate methanol decomposition and the water-gas shift reaction, verifying model accuracy. The effects of temperature, porosity, and operating voltage on methanol SOFC performance were investigated. Results showed output current density increased from 13.60 kA·m⁻² to 14.05 kA·m⁻² as porosity rose from 0.2 to 0.7. As temperature increased from 873 K to 1273 K, current density rose from 72.54 kA·m⁻² to 37.89 kA·m⁻². Increasing anode thickness from 0.1 to 0.8 mm raised current density from 13.17 kA·m⁻² to 15.64 kA·m⁻². These findings provide theoretical foundations and data for optimizing methanol SOFC design and operation.

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.

Graphical Abstract

Solid-state Li⁺/Na⁺ conductors are used as electrolytes in all-solid-state Li/Na batteries. The ion conductivity and electrode stability of solid electrolytes directly determine battery performances. In addition to the solid electrolyte layer, Na⁺ conductors are also used as additives in electrode composites to enhance the charge–discharge properties. In this study, the ion conductivity and Na metal stability of the Na-rich anti-perovskite Na₃OCl were investigated. Na₃OCl was prepared by controlling the Cl⁻/O²⁻ ratio. Dense pellets of Na₃OCl were prepared by sintering. The conductivities of stoichiometric and Cl-excess Na₃OCl are 9.7 × 10⁻⁶ and 3.0 × 10⁻⁵ S/cm at 240 °C, respectively. The Na⁺ vacancies, which were introduced as the charge compensation of Cl⁻/O²⁻ substitution, are considered to be the origin of the conductivity improvement. Off-stoichiometry of Cl⁻/O²⁻ can also be effective when Na₃OCl is used as the anode composite. The decomposition of Na₃OCl at the Na metal interphase was suggested, indicating that Na₃OCl is unstable with Na. These results contradict the current knowledge on the charge–discharge performance of Na₃OCl anode composites. The present results indicate that the Na⁺ conduction properties and stability in Na₃OCl with high crystallinity are different from the in situ-formed Na₃OCl in previously reported anode composites. In conjunction with its low conductivity, decomposition at the Na metal interphase indicates that the direct use of Na₃OCl as a solid electrolyte is challenging.

Due to their high specific capacity, ammonium vanadate salts are commonly utilized as cathode materials for aqueous zinc-ion batteries (AZIBs). However, their inferior efficiency and rate performance have hindered widespread adoption. In order to address these issues, we developed evenly distributed hybrid nanosheets (NVM) of (NH₄)₂V₄O₉ and MnV₂O₆ by introducing manganese ions into (NH₄)₂V₄O₉ through the hydrothermal technique. The results show that AZIB exhibits outstanding rate performance, stable cycle performance, and good efficiency characteristics when NVM as electrode materials. The AZIB has a high specific capacity of 500 mAh g⁻¹ at a current density of 0.1 A·g⁻¹. And it maintains a specific capacity of 350 mAh g⁻¹ after 100 cycles at 1 A·g⁻¹. It exhibits good stable cycle performance, the specific capacity is 140 mAh g⁻¹ after 1000 cycles at 5 A·g⁻¹, retaining 98% of its initial capacity. The addition of manganese ions can reduce the electrode’s diffusion impedance and increase its diffusion coefficient, resulting in a lower voltage window of 0.13 V. The large capacity and high energy efficiency of NVM materials make the battery more widely used in practical applications.

In this study, PtCo alloy nanoparticles (NPs) were successfully synthesized and deposited on nitrogen-rich carbon nanosheets derived from Polypyrrole-g-C₃N₄ using a chemical reduction method. This electrocatalyst not only offers enhanced catalytic efficiency but also significantly improves the stability for the oxygen reduction reaction (ORR) in in acidic medium. In terms of electrocatalytic performance, the PtCo/CN@PPY-g-C₃N₄ catalyst demonstrated a mass activity of 0.378 mA µg_Pt⁻¹ at 0.85 V, 0.131 mA µg_Pt⁻¹ at 0.9 V and a specific activity of 2.900 mA cm_Pt⁻² at 0.85 V, 1.004 mA cm_Pt⁻² at 0.9 V which are respectively 2.3, 2.8 and 10, 12 times higher than those of a commercial 20% Pt/C catalyst (0.166 mA µg_Pt⁻¹ at 0.85 V, 0.046 mA µg_Pt⁻¹ at 0.9 V and 0.285 mA cm_Pt⁻² at 0.85 V, 0.079 mA cm_Pt⁻² at 0.9 V). This indicates superior catalytic activity. Furthermore, after 5000 cycles, the PtCo/CN@PPY-g-C₃N₄ retained approximately 77% at 0.85 V and 83% at 0.9 V of its initial mass activity, with only a 14 mV decrease in the half-wave potential, whereas commercial 20% Pt/C catalyst retained only 40% at0.85 V and 30% at 0.9 V of its initial mass activity. These enhancements can be attributed to the synergistic effects and strong interactions between the Pt–Co alloy nanoparticles and the carbon nitride support. The findings of this study underscore the potential of PtCo/CN@PPY-g-C₃N₄ as a viable and efficient alternative to traditional catalysts in electrochemical applications.

In the present work, it was conducted an electrochemical, kinetic, and morphological investigation of the electrodeposition of palladium (Pd) nanoparticles onto an Indium Tin Oxide (ITO) glass electrode. The electrodeposition was performed using a plating bath containing 0.001 M PdCl₂ and 1 M NH₄Cl at a pH of 6. The results indicate that Pd can be electrodeposited without the influence of hydrogen adsorption/desorption processes by selecting an applied potential range between 1.00 and − 0.6 V. The electrodeposition of Pd is diffusion-controlled, as evidenced by the linear relationship between the peak current (j_p) and the square root of the scan rate (ν¹^/²). The kinetic study reveals a progressive nucleation process, leading to the formation of Pd particles of varying sizes. Morphological analysis using optical microscopy and Atomic Force Microscopy (AFM) demonstrates that particle size decreases as the applied potential to the ITO substrate becomes more negative. AFM images indicate that the average heights of the Pd clusters are 149.5 nm, 91.6 nm, and 79.2 nm at -0.150 V, -0.200 V, and − 0.250 V, respectively; while the diameters of the particles ranged from 120 to 735 nm at -0.150 V, from 80 to 550 nm at -0.200 V, and from 60 to 360 nm at -0.250 V. At -0.300 V, agglomeration of Pd nanoparticles was observed due to the high nucleation rate.

Hard carbons (HCs) are widely used as anode materials for sodium-ion batteries due to their availability, ease of synthesis, and low cost. HCs can store Na ions between stacked sp²-layers of carbon and micropores. In this work, hard carbons are synthesized from 1 M, 2 M, 3 M, 4 M, and 5 M dextrose solutions by hydrothermal synthesis followed by high-temperature calcination at 1100 °C in an argon atmosphere. Among all hard carbons derived from different concentrations of dextrose solutions, hard carbon derived from 3 M dextrose solution delivers superior electrochemical performance compared to other hard carbons. Hard carbon derived from 3 M dextrose solution (DHC-3 M) provides an initial reversible capacity of 273 mAh g⁻¹ with a capacity retention of 82% at the end of 100 charge–discharge cycles at 30 mA g⁻¹. Further, high-rate charge–discharge cycling at 200 mA g⁻¹ shows an initial capacity of 200 mAh g⁻¹ and retains over 61% capacity at the end of 500 cycles. The improved capacity of DHC-3 M is due to the higher d-spacing value and more disorderness, which improve the plateau region capacity due to the intercalation of Na⁺ in the carbon matrix. Besides, 3 M dextrose-derived hard carbons are less agglomerated than other concentrations and show less charge transfer resistance before and after cycling, resulting in improved electrochemical performance.

Graphical Abstract

This article explores the electrochemical reactions in the hybrid material phosphotungstic acid (PW₁₂)/reduced graphene oxide (rGO), resulting from the integration of polyoxometalate (POM) clusters into rGO sheets, aiming for its application in supercapacitors. The synthesis process employs a direct chemical approach, leveraging the anchoring capability of rGO. Morphological analyses confirm the open porous structure of rGO sheets, increasing the number of electroactive sites per geometric area unit and facilitating ion transport to maintain the electrolytic connection between electroactive sites and the solution. The observed low irreversibility is crucial for achieving high power density. A frequency-domain kinetic model is proposed to better understand the electrochemical processes, enabling the extraction of kinetic parameters and the estimation of the amount of accessible and accessed active sites as a function of electric potential, aiding in the selection of active and support materials to increase charge storage capacity and energy density.

Fatty liver and other related diseases are caused mainly by fructose consumption from nonalcoholic sweetened beverages; therefore, the development of new techniques, materials, and practical devices for its quantification is important for clinical diagnosis. In the present work, composites based on zinc oxide (ZnO) and different praseodymium concentrations were prepared by precipitation in alkaline aqueous media. Composites of ZnO/praseodymium were characterized by ultraviolet/visible-near infrared (UV/Vis-NIR) and Fourier transform infrared (FTIR) spectroscopies, thermogravimetry (TGA), X-ray diffraction (XRD) and scanning electron microscopy (SEM). The composites consisted of ZnO microparticles of cabbage-like morphologies with sizes of 850 ± 253 nm and a thickness of 36.6 ± 1 nm, which were decorated with praseodymium particles of rice-like morphology with different sizes depending on the praseodymium concentration. The composites exhibited photoactivity in the UV and visible regions, with characteristic absorbances due to the presence of fluorophores in the near-infrared region. ZnO/praseodymium composites were characterized electrochemically in half-cells under visible light irradiation at different fructose concentrations to determine their detection limit, which was between 30 and 40 mM fructose. The composite with 2% praseodymium with respect to Zn²⁺ showed the best linearity; therefore, it was tested as a photoanode for fructose oxidation in a flexible and transparent photoelectrochemical microfluidic fuel cell with an interval of 5 to 50 mM fructose, with a 40 mM fructose concentration and a power density of 0.142 mW/cm² under illumination compared with 0.101 mW/cm² in the dark (∼ 40% higher).