Journal of Solid State Electrochemistry最新文献

Cyclic voltammetry (CV), differential pulse voltammetry (DPV), and square wave voltammetry (SWV) were employed to investigate the electrochemical behavior of acetaminophen (APAP) at a screen-printed carbon electrode (SPCE) modified with silver nanoparticles (AgNPs) synthesized via an eco-friendly process. Hibiscus rosa-sinensis flower extract acts as a stabilizing and reducing agent to produce AgNPs. UV–Vis spectroscopy, dynamic light scattering (DLS), and X-ray diffraction (XRD) analyses confirmed the formation of the AgNPs. The modified electrode, SPCE/AgNPs, demonstrated an excellent electrochemical response for APAP detection within a linear range of 0.5–100 µmol L⁻¹ with correlation coefficients of 0.995 and 0.993 for DPV and SWV methods, respectively. The limit of detection (LOD) and limit of quantification (LOQ) were 0.14 and 0.28 µmol L⁻¹ for the DPV method and 0.051 and 0.10 µmol L⁻¹ for the SWV method, respectively. The RSD for ten measurements was 0.54% and 0.35% for DPV and SWV, respectively. The proposed sensor was successfully applied to quantify APAP in pharmaceutical samples. Furthermore, it proved selective in determining APAP in the presence of common interfering compounds such as ascorbic acid and caffeine.

A layer-by-layer approach in the assembly of nanomaterials from the atomic layers electrochemically generated by underpotential deposition was reinforced by the development of the method of multiparametric monitoring of surface-restricted electrochemical reactions based on frequency response analysis under nonstationary conditions. The upd in a wide meaning of this term is not restricted to deposition of a monolayer of one metal onto an electrode of different metal but involves also nonmetals, such as Se and Te, their compounds (CdSe, CdTe, CdS, PbTe, PbSe, Bi₂Te₃, etc.) and superlattices, such as (Bi₂)_m(Bi₂Te₃)_n. The experience acquired in the electrochemistry of the underpotential deposition and multilayer assembly can be also helpful in other fields of materials science, such as supercapacitor research, where the frequency response examination of the surface-restricted reactions enables the discrimination between capacitive and noncapacitive currents under conditions preventing from the use of classical impedance spectroscopy and evaluation of energy dissipation in the charge–discharge processes.

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

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

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