Journal of Solid State Electrochemistry最新文献

Bee honey has gained significant interest as a crucial commodity in Brazilian agribusiness, leading to its increased consumption in recent years because of its nutritional properties in humans. Legislation based on the Codex Alimentarius establishes quality control parameters essential for ensuring the safety and quality of honey. These parameters include the measurement of hydroxymethylfurfural (HMF), an indicator of honey quality. Currently, the primary methods for determining HMF concentration in honey are spectrophotometric and chromatographic tests. This study proposes a simpler alternative electroanalytical methodology that uses a screen-printed carbon electrode to monitor the HMF in honey. This portable technique offers advantages over commonly used methods, such as lower cost, similar efficacy, and requirement of only 70 µL of solution per analysis. Square-wave voltammetry was employed to determine HMF in Britton-Robinson buffer (pH 9.0), and the technique was optimized based on the experimental design, generating statistical chemical prediction results. The optimal values for modulation amplitude, step potential, and frequency were 81.5 mV, 22.5 mV, and 5 Hz, respectively. The recovery rate was within the limits established by AOAC International (80–110%), except for the concentration of 6.0 × 10⁻⁷ mol L⁻¹, which showed a 2.07% higher recovery, indicating a minor matrix effect. The calibration curve had an R² value of 99%, with a limit of detection of 6.76 × 10⁻⁸ mol L⁻¹ and a limit of quantification of 2.23 × 10⁻⁷ mol L⁻¹. Therefore, a rapid, cost-effective, and efficient methodology was established to quantify HMF in honey.

Graphical Abstract

A simpler and portable electroanalytical methodology based on screen-printed carbon electrodes to determine the HMF in honey

This paper presents a comparative study of the electrochemical pH sensing characteristics of N-ZnO on a carbon screen-printed electrode (N-ZnO/C) and a silver screen-printed electrode (N-ZnO/Ag). The surface-morphological properties of the film were evaluated using scanning electron microscopy. Electrochemical evaluation was carried out in the presence of common salts present in physiological fluids like NaCl and KCl. Cyclic voltammetry (CV) and chronoamperometry (CA) were carried out to evaluate the response characteristics of the solution under different pHs. Electrochemical impedance spectroscopy (EIS) was carried out to determine the interfacial parameters ruling the pH sensing mechanism for different electrode configurations. The studies revealed that the carbon-based electrodes exhibit stable behavior, with a sensitivity of 17.8 nA·cm⁻²/pH and a linear correlation (r² = 0.996) across a range of acidic to basic conditions, thereby enhancing the sensor’s performance. The carbon electrodes demonstrated superior sensing properties, attributed to their improved stability and conductivity. This advancement in sensor technology offers promising potential for applications requiring reliable and precise measurements.

Enormous scientific interests focused on the improvement of the electrocatalytic activity of counter electrodes for their application in dye-sensitized solar cells (DSSCs). In this regards, we have elaborated a novel gold and platinum (AuPt) nanostructures via direct and indirect electrodeposition techniques; the first one is cyclic voltammetric, while the second one is a combination of amperometric and potentiostatic methods. The as-prepared AuPt nanomaterials, which were characterized by XRD, XPS, SEM, and CA, and electrochemical analysis such as cyclic voltammetry, electrochemical impedance spectroscopy, and Tafel polarization were employed as counter electrode in dye sensitized solar cells. The AuPt counter electrode prepared by cyclic voltammetric technique was the best electrocatalytic activity toward ({text{I}}_{3}^{-}/{text{I}}^{-}) reduction, low charge transfer resistance of 9.2 Ω cm², and good chemical and electrochemical stability in the electrolyte. The assembled cell with the Au/Pt electrode provided a maximum power density of 2.35 mW cm⁻² with an efficiency of 2.35% under back illumination of 100 mW cm⁻² and AM 1.5 G.

Graphical Abstract

Developing new sensors presenting low-cost, portability, and disposability features is of paramount in the electrochemical field. Thus, this work proposes the fabrication of lab-made composite electrodes using acrylonitrile butadiene styrene, graphite, and aluminum oxide. In this investigation, the amount of aluminum oxide (0 to 12.25 w/w) was carefully optimized, and its impact on the electrochemical performance of the electrode was observed using the ferri-ferro redox probe and dopamine (DOP) as a proof of concept. This innovative electrode was characterized by spectroscopy, morphological, elemental, and electrochemical techniques. Using the alumina-loaded electrode, significantly improved cyclic voltammetric responses regarding peak currents and peak-to-peak separation were obtained for both evaluated species. This sensor was integrated into the batch injection analysis system for amperometric monitoring of DOP in synthetic biological fluids (saliva and urine) and tap water. The developed method showed a wide linear range (10 to 1000 µmol L⁻¹), a low detection limit (2.6 µmol L⁻¹), and a high analytical frequency (182 analyses per hour). Furthermore, it was precise (RSD < 5%), accurate (recoveries between 90.5 and 107.3%), and selective. Therefore, it can be considered a low-cost alternative analytical tool for electrochemical sensing of DOP in samples of clinical and environmental interest.

Our energy generation and other industrial processes on which our current lifestyle is based cause significant environmental impacts. Some widely employed industrial processes are major contributors to CO₂ emissions. A prime example is ammonia production, which represents a high energy consumption, utilizes natural gas, and generates hundreds of millions of tons of CO₂ annually. Proper waste treatment, alternatives to fossil fuels, and chemical compound production processes are crucial to address these issues. In this regard, (photo)electrochemical techniques such as electrocatalysis (EC) and photoelectrocatalysis (PEC) can aid in the clean and cost-effective treatment of wastewater while also generating new fuels and commercially valuable chemical compounds. Reduction reactions can be specifically applied to (i) CO₂ molecules, producing fuels; (ii) N₂ molecules, generating NH₃; and (iii) H + species, producing H₂. Oxidation reactions can be employed for organic and inorganic molecules present in real effluents, aiming to treat contaminated water. Electrocatalytic Brazilian research groups have been contributing not only to those redox reaction investigations but also to the synthesis of electrocatalysts for both reactions, making them more cost-effective, specific, and efficient, opening new perspectives in the generation of environmentally friendly chemical compounds with added value, clean energy conversion (non-petroleum energy), and minimizing the economic impact of environmental wastewater treatments. Thus, this work offers for the first time insights into the strengths, challenges, and prospects of electrochemical applications in the fields of energy and environmental remediation in Brazil, highlighting the country’s significance as a source of scientific knowledge on a global scale.

Graphical Abstract

This research focused on the synthesis of gallium oxide (γ-Ga₂O₃) nanoparticles using sol–gel and hydrothermal techniques. X-ray diffraction (XRD), field emission electron microscopy (FESEM), UV–Vis spectrophotometer, Fourier transform infrared spectroscopy (FTIR), cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), calculation of specific capacitance (SC), and specific capacitance (Q) techniques were used. XRD patterns showed the formation of the cubic phase of gallium oxide (γ-Ga₂O₃). The polyhedral and spherical grains can be seen in the FESEM images of the synthesized nanostructures. The band gap values were determined between 4.29 and 4.42 eV. The FTIR results indicate the formation of a gallium oxide structure. The cyclic voltammetry (CV) results are consistent with the redox reactions performed. Samples produced by sol–gel and hydrothermal synthesis, then microwave-annealed, have the highest capacity (SC). They show values of 1172.6 mAh g⁻¹ and 1261.9 mAh g⁻¹, respectively. These results show that these nanoparticles are effective anodes for lithium-ion batteries.

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.

Zinc-nickel (ZN) coatings were deposited on N80 steel substrates using pulsed electrodeposition. The current density of the two-step electrodeposition process was adjusted to promote the formation of micro/nanostructures on the coating surface. Superhydrophobic coatings were obtained by using appropriate current parameters and subsequent modification of the coatings with hexadecyltrimethoxysilane. The results showed that the coating achieved a water contact angle of 157 ± 1° and a sliding angle of 6 ± 1°, indicating that the superhydrophobicity was successfully constructed. In addition, electrochemical tests confirmed the coating’s excellent corrosion resistance. Compared with other samples, the corrosion current density of the coating in 3.5 wt% NaCl solution was significantly reduced, the corrosion inhibition rate reached 94.41%, and the impedance modulus in the low-frequency region of the Bode plot was improved by one order of magnitude compared with that of the blank sample. In conclusion, the prepared superhydrophobic coating has good hydrophobicity and corrosion resistance and has a broad industrial application prospect.

Ternary selenides are an attractive choice for supercapacitor electrode materials owing to their multiple oxidation states, higher electronic conductivity, and better electro activity. However, to attain improved charge storage performance, the electrode materials must be strategically tailored as nanostructured hybrid composites. Herein, we experimentally explore the electrochemical charge storage characteristics of MoO₃@NiCo₂Se₄ nanostructure. MoO₃@NiCo₂Se₄ is synthesized via hydrothermal route coupled with ball milling, varying the milling duration from 0 to 4 h. The MoO₃@NiCo₂Se₄ composite obtained by 4 h ball milling process produced well mixed polymeric molybdates and NiCo₂Se₄ nanostructures with highest surface area of 5.9 m² g⁻¹. The specific capacities obtained from 3-electrode electrochemical measurements are 147 C g⁻¹, 267 C g⁻¹, 286 C g⁻¹, and 366 C g⁻¹, respectively, for MoO₃, NiCo₂Se₄, MoO₃@NiCo₂Se₄-0 h, and MoO₃@NiCo₂Se₄-4 h nanostructures at 2 A g⁻¹. An asymmetric Swagelok device is fabricated for MoO₃@NiCo₂Se₄-4 h//AC electrode material delivering a maximum energy density of 30.4 Wh kg⁻¹ and power density of 1499 W kg⁻¹. This study highlights the significance of MoO₃ in tuning the functional characteristics of NiCo₂Se₄ nanostructures for charge storage applications. The newly developed material shows significant promise as electrode material for further exploration and real-world implementation within the energy storage sector.

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.