Electrochimica Acta最新文献

A novel nonenzymatic electrochemical sensor with high sensitivity for detecting organic phosphate (OPS) in medicinal herbs was fabricated based on a Mg-Al layered double hydroxide (Mg-Al LDH) nanocomposite glassy carbon electrode (GCE) modified with a poly-m-amino-benzenesulfonic acid (p-m-ABSA) film. Depositing Mg-Al LDH nanocomposites onto the surface of the p-m-ABSA composite resulted in an effective electrical response by increasing the electrode surface area and enhancing the electron transfer process, so the electrocatalytic activity was significantly enhanced. The research illustrated that the fabricated sensor (Mg-Al LDH/p-m-ABSA/GCE) exhibited strong affinity, high sensitivity, and selectivity towards methyl parathion (MP) and fenitrothion (FNT). Scanning electron microscopy (SEM) was used to characterize the surface morphology of the modified electrode and showed that the p-m-ABSA film and a few p-m-ABSA nanoparticles were coated on the surface. The surface area of the electrode was further enlarged by Mg-Al LDH owing to their layered nanostructure. Under optimal conditions, the anodic current had a linear relation equal to 0.1∼20.0 µM MP and 0.01∼50.0 µM FNT, with detection limits (S/N = 3) of 33.0 nM MP and 3.5 nM FNT, respectively. Furthermore, Mg-Al LDH/p-m-ABSA/GCE was successfully used for the detection of MP and FNT in Astragalus and Magnolia medicinal herb samples.

The primary requirements for a viable supercapacitor electrode material are increased energy density, high specific capacitance, and excellent cycle stability. The desired outcome may be attained by combining diverse active materials. In this research, two Bi-MOFs with 1,4-benzenetdicarboxylic (H₂BDC) and 1,3,5-benzenetricarboxylic (H₃BTC) organic linkers were synthesized by facile solvothermal method and bonded on the surface of graphene oxide to produce FGO-Bi(BTC) and FGO-Bi(BDC) composites. The electrochemical characteristics of the two electroactive compounds were evaluated by GCD, CV, and EIS tests in a three-electrode setup. Comparative electrochemical analyses demonstrated that the composites exhibit remarkable performance with reduced charge transfer resistance. In the three-electrode configuration, FGO-Bi(BDC) and FGO-Bi(BTC) exhibited specific capacitances of 559 and 422 F g^-1 at 1 A g^-1, respectively. After conducting 10,000 cycles of charge and discharge at 8 A g^-1, the FGO-Bi(BDC) and FGO-Bi(BTC) electrodes exhibited impressive retention rates of 97.6% and 95.64% for their initial specific capacitance (C_s). Notably, the three-electrode system's results indicated superior electrochemical performance of the FGO-Bi(BDC) electrode over the FGO-Bi(BTC) electrode. This superiority is attributed to the FGO-Bi(BDC)'s larger specific surface area (SSA) and reduced oxygen concentration. For a more practical assessment, the FGO-Bi(BDC) composite was selected for evaluation in the two-electrode system. The FGO-Bi(BDC)//FGO-Bi(BDC) two-electrode system demonstrated a cyclic stability of 94.2% over 10,000 cycles, attaining a substantial C_s of 295 F g^-1 at 1 A g^-1. Moreover, it accomplished a power density of 750 W kg^-1 and an energy density of 34.61 Wh kg^-1, emphasizing the exceptional electrochemical attributes that position the FGO-Bi(BDC) composite as a promising electrode material for supercapacitors.

Rare-earth metal-free Li₂ZrCl₆ has recently attracted much attention as a promising solid electrolyte for all-solid-state batteries due to its cost-effectiveness. This first-principles study using van der Waals correction clarifies the Li diffusion mechanism in trigonal α- and monoclinic β-Li₂ZrCl₆. In the most stable α- and β-Li₂ZrCl₆ structures obtained from systematic investigations, Li and Zr ions prefer to exist in the same layer, forming two-dimensional Zr/Li layers with Li ions interspersed between ZrCl₆ octahedra. When Li ions diffuse in α- and β-Li₂ZrCl₆, they escape from the Zr/Li layer along the out-of-plane direction and move to the Zr-free layer, where they diffuse freely along the in-plane direction. Thus, Li diffusion in Li₂ZrCl₆ is characterized by interlayer diffusion between the Zr/Li and Li layers followed by intralayer diffusion in the Li layer. The interlayer/intralayer diffusion, resulting in the highest conductivity of 5.4 × 10⁻⁵ S cm⁻¹ for α-Li₂ZrCl₆, is enabled by a synergistic effect of two Li ions, where one Li ion already present in the Li layer promotes the other adjacent Li ion to escape from the Zr/Li layer. Individual Li ions vibrate at the stable octahedral site for a long time and then quickly jump to another octahedral site via the intermediate tetrahedral site, which is identified as the atomic-scale Li jump process in Li₂ZrCl₆.

In the present study, the inhibition mechanisms and the adsorption kinetics of a film-forming amine (N-oleyl-1,3-propanediamine, OLDA) were investigated on a carbon steel surface in various corrosive environments, relevant to industrial water/steam circuits. In situ electrochemical characterizations including Electrochemical Impedance Spectroscopy (EIS) and polarization curves were combined with ex situ surface analysis, such as Polarization Modulation Infrared Reflection Absorption Spectroscopy (PM-IRRAS) and Raman Spectroscopy. OLDA acts as a mixed inhibitor for all the studied conditions. In a deaerated medium, OLDA adsorption is temperature-independent (25 °C–50 °C) and PM-IRRAS analyses reveal the formation of a monolayer (thickness of about 1.6 nm) on the steel surface. In aerated media, mixed OLDA/corrosion products layers are formed exceeding the monolayer thickness (about 20 nm). Finally, the presence of a well-defined time constant in the high frequency range in impedance spectra is correlated with the accumulation of OLDA molecules with corrosion products.

CoS₂ with high thermal stability is commonly used as cathode material for thermal batteries, however, its practical performance is limited by insufficient electrochemical reactions during discharge. Enlighted by metal-doping that can regulate the electronic environment and lattice structure, high-energy Co_0.8Fe_0.2S₂ is successfully prepared by solid-state methods. Remarkably, with a current density of 0.3 A·cm⁻² at a cutoff voltage of 1.42 V under 550 °C, Co_0.8Fe_0.2S₂ exhibits excellent performance with a prolonged discharge platform and decreased resistance (0.23 Ω), generating an ultrahigh specific capacity of 652 mAh·g⁻¹_, which is 31 % higher than that of pure CoS₂. Our research indicates that Co_0.8Fe_0.2S₂ is suitable for high-energy and high-temperature thermal batteries. The feasibility of solid-state synthesis of pure-phase bimetallic disulfides has been verified as well, paving the way for industrial application of Co_0.8Fe_0.2S₂.

Silicon is capable of delivering a high theoretical specific capacity (4200 mAh g^-1) in lithium-ion batteries. However, silicon has poor electrical conductivity, huge volume expansion (∼300%), and unstable solid electrolyte interface (SEI) film, especially for micron-sized silicon particles. We proposed and prepared a novel vertical carbon (VG) coating on a porous silicon (p-Si) microparticle structure, which effectively alleviated the volume expansion and inhibited the interface reaction. The synthesized porous silicon p-Si@VG composite exhibited significant enhanced cycling stability and an excellent reversible capacity of 1563 mAh g^-1 (capacity retention of 48.6%) after 200 cycles. The vertical carbon nanosheet structure constructed a three-dimensional conductive network. Therefore, the p-Si@VG composite showed better rate capability and higher lithium-ion diffusion rates. This work is expected to promote the application of micron Si-based composites in lithium-ion batteries.

Sulfide SSEs (solid-state electrolytes) with high ionic conductivity are attractive for developing high-safety all-solid-state batteries (ASSBs). However, the poor chemical stability of sulfide SSEs toward moisture is a significant problem. Though the decomposition products when exposed to moisture and a possible property recovery by heat treatment are reported, the evolution of surface species in related to moisture exposure and to heat treatment is not clearly identified. This study applies in situ DRIFTS (diffuse reflectance infrared Fourier-transformed spectroscopy) analysis to examine the evolution of the surface species over pristine Li₆PS₅Cl (LPSC), during moisture exposure, and during heat treatment, complementary with tools like XRD, Raman, etc. The observed surface impurities over pristine LPSC include LiCl·H₂O, LiOH·H₂O, S₃P-SH, PS_4-xO_x, SO_x and carbonate species. Moisture exposure leads to increasing accumulation of these species over LPSC and evolving hydrogen sulfide. A stepwise heat treatment up to 480 °C illustrates the sequential removal of hydrated water, the decomposition of carbonate, LiOH, and PS_4-xO_x, leaving species like LiCl, Li₂O, and PO₄ on the surface. The EIS results shows a gradual increase in the ionic conductivity of LPSC with increasing heating temperature, mainly owing to the decreasing surface layer impedance. This strongly suggests that the surface species govern the properties of LPSC. When using the pristine LPSC after heat treatment at 480 °C, the Li||pristine LPSCHT||Li symmetric cell demonstrates a decreased polarization and a much-enhanced cycle stability comparing to the Li||pristine LPSC||Li symmetric cell.

In this work, Poly(o-phenylenediamine) (POPD) and zinc oxide (ZnO) nanoparticles were electrochemically deposited on GCN (graphitic carbon nitride) coated TCFP (Toray carbon fiber paper) electrode. The modified electrode ZnO-POPD-GCN-TCFP was assessed by Field emission scanning electron microscopy (FESEM), X-ray diffraction analysis (XRD), and X-ray photoelectron spectroscopy (XPS) studies. The electrochemical studies were carried out via cyclic voltammetry (CV) and electrochemical impedance spectroscopic (EIS) methods. The developed electrode was employed for the oxidation of furfuryl alcohol (FA) using 4-ACT (4-acetamido TEMPO) as a mediator in an alkaline medium via bulk electrolysis. Proton nuclear magnetic resonance (¹H NMR) spectroscopy was used to characterize the final product. The oxidation of FA to furfural was accelerated by the heterogeneous catalyst ZnO-POPD-GCN-TCFP electrode owing to its good electrocatalytic activity and stability. Hence, a sustainable electrochemical method for synthesizing furfural, with significance in the realm of green chemistry, was developed. The Electro-oxidation of FA offers a clean alternative to traditional methods utilizing electricity, potentially from renewable sources, to drive the reaction, reducing reliance on harsh chemicals and minimizing environmental impact. By adjusting parameters like electrode potential and electrolyte composition, it is possible to optimize the reaction conditions for furfural production with optimal yield, which has several applications in daily life.

We describe the design and development of a rotating disk electrode (RDE) cell capable of operating at pressures up to 200 bar and temperatures up to 200 °C. This setup enables electrochemical surface characterization through techniques such as voltammetry and impedance spectroscopy, under different mass transport regimes. Furthermore, evaluation of catalytic performance, including CO₂ reduction, is possible as the system works in a semi-continuous mode interfaced with online gas sample measurements. As a proof of concept of the high-pressure cell designed, we examined the temperature-dependent changes in the cyclic voltammograms (CVs) of polycrystalline gold up to 150 °C and 50 bar. Additionally, online catalytic performance of CO₂ reduction to CO on a rotating polycrystalline gold disk electrode was investigated under different pressure and temperature. Our results indicate a positive impact of temperature on the faradaic efficiency (FE) towards CO up to 50 °C, beyond which a rapid drop in performance was observed at atmospheric pressure. Conversely, increasing pressure positively affected CO₂ solubility in the electrolyte, resulting in enhanced FE towards CO, reaching approximately 90 % at 6 bar compared to 40 % at atmospheric pressure. Notably, further increases in pressure did not significantly alter the FE, but led to higher current densities. Moreover, at pressures exceeding 6 bar, we observed a plateau in efficiency at temperatures higher than 50 °C. This observation suggests that increasing pressure can sustain CO₂ electrolysis, validating the hypothesis that increasing CO₂ solubility would suppress catalytic decay at higher temperatures. This study opens up promising avenues for future investigations in electrocatalysis, ranging from fundamental explorations of surface modifications induced by variations in temperature and pressure to the development of high-performance catalysts.

A high entropy oxides (HEOs) has been proposed as a promising electrocatalyst for electrochemical water splitting reaction owing to their distinctive catalytic activity, stability, and tuneable electronic structure. In this work, a carbon infused HEOs (Ni_0.2 Co_0.2 Cr_0.2 Mn_0.2 V_0.2)₃O₄ nanoparticles were synthesized via a single step process through a carbonaceous thermal plasma (Ar-CO₂CH₄) medium. Here, carbon infused HEOs were utilized as an electrocatalyst for water splitting reaction in 1 M KOH electrolyte. A Carbon rich HEOs (HEO C6) nanoparticle exhibits excellent oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) performance with an overpotential of 243 and 217 mV to attain a current density of 50 mA cm^-2, respectively. The fabricated two-electrode device requires only a 1.596 V as cell voltage to meet a current density of 10 mA cm^-2. This study provides a new platform for a large-scale hydrogen production by utilizing carbon supported HEOs as an electrocatalyst.