Journal of Solid State Electrochemistry最新文献

Abstract

Once the efficiency of solar energy-converting devices depends on the population of the electron–hole pairs (excitons), one way of increasing the conversion efficiency of photoactive materials is using electron-accepting materials, which acts on the separation efficiency of these pairs by collecting the electrons. In such a way, carbon nitride (C₃N₄) has been studied as an electron acceptor. With simple synthesis and easy tailoring properties, this material becomes a promising candidate in organic photovoltaic cells. Thus, the objective was to evaluate the photocurrent as a function of exciton properties. Then, P3HT was obtained by redox polymerization and C₃N₄ by urea pyrolysis. Photoelectrochemical and spectroscopic measurements were performed to characterize the electrodes. In addition, theoretical calculations were carried out using TD-DFT. It was observed that a photocurrent 3-fold increased in relation to the pure P3HT film (from 12.1 up to 33.2 µA cm^-2), attributed to the increase in the hole-electron separation efficiency, with an increase in their lifetime (from 0.18 to 0.42 ms). The electron transport was also boosted (an increase of 2.1(times )10^-3 cm² V^-1 s^-1). The theoretical calculations suggest that the structural modification of C₃N₄ affects the photocurrent due to the charge delocalization induced by the torsion of the triazine units. Besides, the photocurrent values achieved in this work were not expressive; the results pointed out that the association P3HT+C₃N₄ is promissory. The further optimization of these systems by heat treatment, type of solvent, and deposition method could lead to better results. Additionally, the theoretical results demonstrated that minor system modifications could improve the photocurrent values.

Graphical abstract

The synergetic effect of the composite obtained between poly(3-hexylthiophene) and carbon nitride in the appropriate proportion leads to a 3-fold increase in photocurrent due to the improvement in the properties of the photogenerated excintons.

Ni coatings are widely industrially applied due to their excellent properties like resistance to corrosion and wear, increasing the durability of coated surfaces. Ni electrodeposits on steel were produced from an alternative bath to the traditional Watts type, using aspartic acid as a complexing agent at pH = 5 and 11. Scanning Electron Microscopy micrographs revealed that all deposits obtained from the acid and alkaline baths showed smooth morphology with fine grains and no cracks. The smoothest deposits were obtained at deposition current of − 2.05 mA cm⁻² for both baths. The X-ray diffraction patterns of Nickel deposits obtained at pH = 5 and 11 indicated phases of pure Ni with the following reflections Ni(200), Ni (220), Ni (311), and a lower crystallinity for the deposits obtained at pH = 11 compared to that obtained at pH = 5. Adherence tests showed that the Ni coatings produced adhered well to the steel substrate, irrespective of the pH and deposition current density. By open circuit potential and linear polarizations, it was observed that Ni deposits presented a lower corrosion current and more positive corrosion potential than that of steel, indicating protection against corrosion, with those produced with j_dep = -2.05 mA cm⁻² responsible for the best protection and j_dep = -5.00 mA cm⁻² (pH = 11) the lowest protection.

Graphical abstract

Agglomerated nanorods of lead phosphate have been synthesized from the reaction of lead acetate prepared from waste lead paste and Na₂HPO₄, which is used as an additive for the PbSO₄-negative electrode of a lead-acid cell. It has been found that lead phosphate can be all converted to lead sulfate in 36 wt.% sulfuric acid electrolyte and generate phosphoric acid, and the negative active material containing 1 wt.% lead phosphate discharges a capacity of 111 mAh g⁻¹ at 100 mA g⁻¹ till 1.75 V; it still discharges 78 mAh g⁻¹ after 1200 cycles, which is 10.1% higher than the blank PbSO₄ electrode. It is believed that phosphoric acid could remove the non-conductive oxide on the lead alloy grid; thus, a better conductive network could be built. Also, phosphoric acid is adsorbed on PbSO₄ particles, which can improve the reversibility of the electrode and diminish the shedding of PbSO₄.

An alternative method based on electrochemical techniques for separation and purification of iodine in the presence of ruthenium, molybdenum, and tellurium, which are some elements resultants from uranium fission reaction, is proposed. For this, all elements were electrochemically characterized using the cyclic voltammetry technique. All the characterization and separation were performed using different parameters, such as temperature, pH, concentration, and potential, aiming to determine the optimized operation conditions to achieve the highest separation yield. The highest iodine yields were observed in acidic medium, at 298 and 313 K, and in lower iodine concentrations, which resulted in a separation rate of 45%. On the other hand, the iodine separation in basic medium resulted in very poor yields, indicating that the separation is not efficient in pH > 8.

Graphical Abstract

In this research, the aim is to develop MWCNT@Ni-BTC metal–organic framework–modified glassy carbon electrodes for the preparation of a simple electrochemical method to measure levofloxacin. The composite modifier was synthesized via the one-step solvothermal method. The electrode surface modifiers were characterized using scanning electron microscopy and FT-IR. The concurrent application of these two particles notably enhances levofloxacin oxidation current (3.2 times), facilitating its measurement at trace levels. The oxidation current on the modified electrode was controlled by diffusion, and the diffusion coefficient of levofloxacin was determined to be 1.2 × 10⁻⁶ cm² s⁻¹. The proposed method had a linear dynamic range from 2.0 to 100.0 µmol L⁻¹ of levofloxacin and a detection limit of 0.2 µmol L⁻¹. The relative standard deviation for measuring 20.0 µmol L⁻¹ of levofloxacin was obtained at 2.8% (n = 6), and less than a 5% decrease in oxidation current was observed within 15 days. The modified electrodes were successfully utilized for the determination of levofloxacin in urine samples.

The growing concern regarding contamination from pharmaceuticals, cosmetics, and personal care products highlights the urgent need to address this significant environmental and public health challenges. Parabens are widely used as preservatives. Its use is already prohibited in Europe and the USA but remains permitted in Brazil. Even at low concentrations, parabens pose risks to human health, the environment, and animals. Ineffective water resource management and the limitations of traditional effluent treatment methods intensify this issue. This study investigated the potential of electrochemical and photo-assisted electrochemical technologies in degrading Phenonip™, an industrial preservative composed of a mixture of parabens and phenoxyethanol. Two types of commercial anodes were employed: boron-doped diamond (BDD) and the Dimensionally Stable Anode (DSA^®). The efficiency of these processes was assessed in relation to applied current density, with monitoring of organic carbon levels, contaminant concentrations, energy consumption, and pH. As expected, the time required for complete removal of all contaminants from the sample decreased with higher current densities. However, at elevated current densities, a noticeable increase in energy consumption was observed. In the case of the photo-assisted electrochemical system, an interesting trend emerged: energy consumption decreased as current density increased, attributed to the significantly shorter time needed for complete contaminant removal compared to the traditional electrochemical process. Furthermore, a significant shift in the kinetic behavior of these compounds removal was observed once nearly 80% of the parabens were removed, indicating an alteration in the rate-limiting step or reaction mechanism of the degradation process. These results provide valuable insights into the potential applications of these innovative methods in addressing the urgent challenge of removing contaminants from industrial effluents.

Graphical abstract

Chagas disease (CD) is an endemic disease in America that affects impoverished communities. It is caused by the protozoan Trypanosoma cruzi, which is transmitted by triatomine insects known as kissing bugs. Considering the treatment effectiveness, early detection of the disease is crucial to control its impact on public health. In this study, we developed a low-cost immunosensor in which pencil graphite electrodes (PGEs) were functionalized by electropolymerization of monomers 2-aminobenzamide (2AB), 4-aminobenzoic acid (4ABA), 4-hydroxybenzoic acid (4HBA), 4-hydroxyphenylacetic acid (4HPA), and 4-aminophenylacetic acid (4APA). Electrochemical and morphological studies confirmed the successful modification of PGEs for all investigated compounds. The bioreceptor IBMP 8.1, a recombinant antigen, was immobilized on each functionalized platform. Electrochemical impedance spectroscopy identified poly(4HPA) as the most effective material for functionalizing PGEs and consequently recognizing the anti-T. cruzi antibodies, leading to their selection for subsequent optimization of the transducer. The use of silver nanoparticles to improve sensitivity was also investigated. The conditions for immobilizing the antigen, blocking the protein, and the dilution and response time of the device were optimized. Cross-reactivity studies with other diseases have demonstrated the high specificity of immunosensors. Reproducibility and repeatability tests showed relative standard deviation values of 7.3% (± 2.4) and 5.6% (± 1.8), respectively, for the 20 sensors. Furthermore, the stability over a three-month period (n = 20) showed a 32% decrease in response at 25 °C and a 12% decrease at 4 °C. These results indicated the potential of PGE/poly(4HPA) for rapid and accurate CD detection.

Graphical Abstract

Hydrogen peroxide (H₂O₂) production through a two-electron oxygen reduction reaction (ORR) pathway presents a promising alternative to the traditional energy-consumed anthraquinone process. In this work, a low-cost and effective catalyst of carbon fiber (CF) derived from bacterial cellulose is utilized for H₂O₂ electroproduction. The CF electrode is treated under different atmospheres, and the electrode treated under an inert atmosphere exhibits excellent H₂O₂ production performance. The inert atmosphere-treated CF electrode delivers a high H₂O₂ production yield of 2200 mg L⁻¹ h⁻¹ with a remarkable faradaic efficiency of 95%. Interestingly, the electrode treated under a reductive atmosphere also shows high H₂O₂ production rate after cycle test. Physical characterization confirms that the oxygen functional groups and the unique structure contribute to the superior performance of the CF electrode. These results indicate that the H₂O₂ production performance should be evaluated under practical operating conditions for large-scale. These findings open a new avenue towards the development of low-cost electrocatalysts for H₂O₂ electrosynthesis, and offer new opportunities for waste biomass utilization.

In this study, high-performance Ni-W–P/AlN composite coatings were fabricated through pulsed electrodeposition. Subsequently, the effect of the introduction of AlN nanoparticles on the properties of Ni-W–P coatings was investigated and further determined the optimum addition of AlN particles. The results indicate that the incorporation of AlN nanoparticles reduces the coating’s grain size and mitigates microcrack defects observable in Ni-W–P coatings. Of significance, a bath concentration of 1.5 g/L AlN yields the coating with the most superior characteristics. Due to the enhancement of the mechanical properties of the coating by AlN, the hardness of the Ni-W–P/AlN composite coating is increased from 360.6 (Ni-W–P coating) to 620.7 HV, and the average coefficient of friction was decreased from 0.601 (Ni-W–P coating) to 0.356. Furthermore, the coating’s corrosion resistance was examined in a 3.5% NaCl solution, which had a 4.93 mg/L dissolved oxygen level, to assess its durability under corrosive conditions. Notably, the charge transfer resistance (R_ct) sees a substantial increase, rising from 2256 Ω·cm² (Ni-W–P coating) to 1.88 × 10⁴ Ω·cm², while the corrosion current density experiences a decline, dropping from 24.17 (Ni-W–P coating) to 1.78 μA/cm². This study provides a new direction for the development of a high-performance anticorrosive and wear-resistant coating strategy.

Sodium-ion batteries are gaining broad application prospects in the field of new energy due to their high energy density, low cost, and good safety. However, the irreversible phase transformation of layered oxides during charge and discharge cycles limits their long-term cycling performance and practicality. This article utilizes the sol–gel method to prepare a stable Na_0.7MnO₂ (NMO) crystal phase and explores the effects of double doping with Fe and Co on the microstructure and electrochemical properties of Na_0.7MnO₂. The XRD pattern indicates that Fe and Co ions were successfully incorporated into the lattice of the Na-Mn–O system, stabilizing the P2 crystal phase and increasing the sodium layer spacing. Na_0.7Co_0.1Fe_0.1Mn_0.8O₂(NCFMO) can deliver an initial capacity of 109.78 mAh/g, with an average operating voltage of 3 V, and retains a capacity retention rate of 96.31% after 100 cycles. Moreover, at a current density of 0.2 C and a voltage range of 1.5–4.5 V, the cycle charge–discharge specific capacity reaches 226.08 and 159.3 mAh/g, respectively, demonstrating excellent cycle and rate performance.

Graphical abstract

The cycle performance of the material Na_0.7Co_0.1Fe_0.1Mn_0.8O₂ in different voltage ranges is tested in the figure, and it shows excellent performance in the voltage range of 1.5–4.5 V.