Journal of Solid State Electrochemistry最新文献

Co-free and Ni-rich LiNi_0.95Mn_0.05O₂ (NM95) cathodes are expected to be widely employed in power batteries due to their high charge storage capacity and cost-effectiveness. However, the loss of Co and increase in Ni contents result in highly active surfaces and unstable structures, compromising rate capability and cyclic stability. Herein, polyaniline-polyethylene glycol (PANI-PEG) coating layer, with excellent electronic and Li-ion conductivity, is introduced on NM95 surface to enhance charge transfer properties and cyclic stability. Several material and electrochemical characterization techniques, such as XRD, SEM, EDS, TEM, XPS, 4-point probe, CV and EIS, are utilized to unveil the positive influence of PANI-PEG on electrochemical performance. The results reveal that PANI-PEG layer can promote electron and Li⁺ conduction of NM95 due to the excellent electronic and Li⁺ conductivities. Besides, PANI-PEG acts as protective layer to hinder the corrosion of electrolyte and suppress side reactions. It is revealed that NM95 cathode coated with PANI-PEG with a mass ratio of 4/6, exhibits excellent initial capacity, as high as 219.4 and 163.1 mAh/g at 1 C and 5 C, respectively, and maintains capacity retention of 94.7% (1 C, 100th cycle) and 79.0% (5 C, 200th) under cut-off voltage of 4.3 V (vs. Li/Li⁺). Moreover, NM95 exhibits capacity retention of 70.7% after 100 charge/discharge cycles at 1 C within voltage range of 2.7 to 4.5 V (vs. Li/Li⁺). These results indicate that coating electronic/Li⁺ conductor is effective strategy to enhance rate performance and cyclic stability of Co-free and Ni-rich cathodes.

As a model of passivation at a micro or nanoparticle, we have modelled a passivating reaction at a microelectrode of hemispherical geometry. The reaction is considered to lead to either the formation of a surface-bound species or diffusion of product into bulk solution. A dimensionless parameter, p, of value 0 to 1.0 can be used to describe the balance between the two processes. We have simulated the first two linear sweep voltammograms (LSV) under different values of p and have simulated the peak width of the first LSV under different values of scan rate and p. These simulations were used to relate the peak width to the value of p. The results were compared to the characteristics of passivation at a microdisk electrode. The equation was used to analyse the oxidation of dopamine at hemispherical Ga electrodes, fabricated by the deposition of liquid phase Ga onto Pt microdisks.

An analytical study of the effect of gadolinium-doped ceria (GDC) electrolyte parameters on the output voltage, output power, open circuit no-load voltage, and leakage current is carried out for solid oxide fuel cell (SOFC). Conductivity due to both ions and electrons is considered for GDC electrolytes. The model incorporates various polarization losses such as activation overpotential, concentration overpotential, and ohmic potential losses in order to study the effect of electrolyte parameters on output voltage. The output voltage and, hence, the power density obtained from the model closely match the experimental reports, thus validating the model. Subsequently, the open circuit no-load voltage model and no-load leakage current are used to study the effect of electrolyte thickness and electronic conductivity on it during no-load conditions. During loaded condition, the model relating the electronic current with the ionic current is employed to analyze the effect of various SOFC parameters governing the electronic current density. This study will be instrumental in designing SOFC with low leakage current density and high output power in order to enhance the performance of SOFC.

The work reported herein describes the synthesis of a 3D material UiO-66(Zr)-NH-OC-MWCNT by combining a synthesized metal–organic framework UiO-66(Zr)-NH₂ and a carboxy functionalized multi-walled carbon nanotube MWCNT-COOH via an amide linkage and demonstrated its application for simultaneous electrochemical determination of two benzimidazole fungicides-carbendazim and thiabendazole. Different analytical techniques like Fourier transform infrared spectroscopy, X-ray diffraction analysis, Brunauer–Emmett–Teller analysis, and Field emission scanning electron microscopy were employed to characterize all the synthesized materials. The electrochemical characterization of the fabricated electrode was carried out using cyclic voltammetry and electrochemical impedance spectroscopy. Cyclic voltammetry and differential pulse voltammetry techniques have been used for the electroanalysis of carbendazim and thiabendazole. A limit of detection of 0.077 µM and 0.557 µM, respectively, have been obtained in the calibration range of 0.1 to 40 µM for carbendazim and 1 to 40 µM for thiabendazole, after optimization of several parameters which are susceptible to the sensitivity and selectivity of the developed sensor. Furthermore, with satisfactory results from the study of interferences, repeatability, and reproducibility, the proposed electrochemical sensor was successfully applied for analysis of carbendazim and thiabendazole in real samples.

Graphical Abstract

On March 11, 2020, the World Health Organization declared the coronavirus disease pandemic, caused by the SARS-CoV-2 virus. This declaration propelled the drug hydroxychloroquine into the global spotlight, as it was identified as a potential early treatment for the disease. Consequently, there was a surge in its consumption worldwide, particularly in Brazil. This increased usage has raised concerns about the potential contamination of natural water sources. In response to this concern, the present study proposes an electroanalytical method for detecting hydroxychloroquine in pharmaceutical and drinking water samples. The method aims to study the effects of modifying the sensor with carbon black Super P for HCQ detection, as well as improving the reproducibility and repeatability of the SPCB/GCE. The detection method and sensor modification have been thoroughly optimized for hydroxychloroquine detection. The optimal analysis conditions were established with a concentration of 5.0 mg mL⁻¹ of SPCB, a pH of 7.00, and a preconcentration time of 2 min. The detection and quantification limits were determined to be 0.0093 µmol L⁻¹ and 0.0312 µmol L⁻¹, respectively, with a linear range between 0.10 and 10.0 µmol L⁻¹. Analyses conducted on fortified samples indicated recovery responses of 110% for tap water and 100.5% for drug samples, demonstrating the method’s high accuracy, particularly for pharmaceutical samples.

This paper reports that the self-doped TiO₂ nanotubes (SD–TNT) electrode obtained by cathodic polarization promotes a significant decrease in the band gap value and an increase in electrode conductivity, due to the formation of Ti³⁺ sites and oxygen vacancies. A mechanism for the electrochemical self-doping of TNT electrode and its potential applicability as an impedimetric sensing platform for the target molecule methylene blue (MB) dye was proposed. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) studies made it possible to determine that the charge transfer process in the self-doping process is associated with the stability of H⁺ species. A 2² full factorial design (FFD) combined with response surface methodology (RSM) was employed to find the optimal operational conditions of the impedimetric sensor, which were equal to −1.4 V at pH 7.0. In this optimized condition, a linear relationship (R² = 0.999) for the MB concentration range of 0.10 to 1.75 mg L⁻¹ as a function of the charge transfer resistance (R_ct) was found. Finally, it was possible to correlate the self-doping process of TNT with the impedimetric behavior, indicating that this system can be used for other cationic compounds of interest.

Graphical abstract

Electrocatalytic reduction of CO₂ to valuable chemicals can alleviate the energy crisis and reduce the greenhouse effect. Herein, bimetallic Bi_xIn_y (x, y is percentage composition) nanoparticles (NPs) were successfully prepared and utilized as electrocatalysts for electrochemical conversion of CO₂ to formate. By changing the Bi/In atom ratio and varying the amount of surfactant PVP and solvent DMF, the surface morphology of and the electronic structure of Bi_xIn_y catalysts can be optimized. The optimized Bi_88.77In_11.23 NPs were the most favorable for formate formation and the FE (Faradaic efficiency) of formate reached 94.29% at a potential of − 1.0 V (vs. RHE). The DFT calculations confirmed that the synergistic effect of bimetallic and dense nanoparticle structures promotes the adsorption of CO₂ molecules and major ^*OCHO intermediates at active sites, thus accelerating the reaction rate. The Bi_88.77In_11.23 NPs were further employed as cathode coupling oxygen evolution reaction to construct a two-electrode electrolysis system (CO₂RR‖OER). The whole electrolysis needed a low cell voltage of 3.4 V to deliver 10 mA/cm². This study will provide an efficient approach to enhance the activity and selectivity for CO₂RR by the synergistic effect of bimetal.

Endosulfan is an organochlorine pesticide widely used in agriculture to protect crops such as cotton, soybeans, coffee, tea, cereals, fruits, vegetables, and grains from pests. However, exposure to low concentrations of endosulfan causes harmful effects on humans’ health. Therefore, the determination of endosulfan in food samples by a fast, simple, and cost-effective method is pivotal. In this study, an electrochemical sensor based on a polyaniline/Fe-ZnO-modified glassy carbon electrode (PANI/Fe-ZnO/GCE) was developed for the determination of endosulfan in vegetables. The synthesized nanomaterials were characterized by Fourier transform infrared (FT-IR), X-ray diffraction (XRD), and scanning electron microscopy (SEM). PANI/Fe-ZnO/GCE showed remarkable electrocatalytic activity for the determination of endosulfan in vegetables. It also exhibited a good linear response to endosulfan concentrations ranging from 1 to 400 µM. The method displayed a low detection limit (LOD) of 0.003 µM. The sensor showed good selectivity, long-term stability, good repeatability, and within-lab reproducibility. It was also applied for the determination of endosulfan in tomatoes and potatoes, with acceptable recoveries ranging from 87.00 to 96.80%.

Graphical abstract

Graphical illustration of PANI/Fe-ZnO modified glassy carbon electrode for endosulfan determination in vegetables