Journal of Electroanalytical Chemistry最新文献

The possibility of producing high-purity and ligand-free nanoparticles makes laser ablation in liquids (LAL) an interesting method to produce gold nanoparticles (AuNPs). AuNPs play an important role in the manufacture of electrochemical sensors due to their excellent electrical conductivity and chemical stability. In this study, stable and ligand-free AuNPs were produced by LAL (AuNP/LAL) using a nanosecond pulsed laser. The control of this single-step production was facilitated by adding sodium chloride (NaCl), resulting in the reduction of AuNPs size (10 ± 2 nm) and higher stability (monitored for 12 weeks). The potential of NaCl-stabilized AuNPs/LAL as modifiers agents were investigated for dopamine (DA) sensing by cyclic voltammetry for the first time. The novel electrochemical sensor (GCE/AuNPs.LAL/Nafion) achieved an increase in the peak current of ca. 3 and 6 times for oxidation and reduction, respectively. A comparison of chemical syntheses and LAL approaches was given for electrochemical sensing applications; the AuNPs/LAL showed to be more efficient in facilitating the electronic transfer and electrocatalytic reactions. The estimated limit of detection values for DA sensing was 0.77 µmol/L (oxidation) and 1.08 µmol/L (reduction). The method hereby proposed is promising for clinical applications as the new electrochemical sensor allowed proper sensitivity for DA.

Graphite and its derivatives, as cathode materials for aluminum-ion batteries (AIBs), have excellent cyclic properties, so they have garnered significant research interest over the years. Preliminary research has demonstrated that expanded graphite (EG) exhibits a dual aluminum storage mechanism, i.e., intercalation (1.5–2.5 V) and adsorption (0.5–2.5 V). In this study, for the adsorption mechanism, we propose positively charged EG as a cathode material for AIBs. Using electrostatic modification methods, we found that positive charge on the surface of EG can depress the surface barrier and lead to the adsorption of more anions through electrostatic forces during chemical reactions. Moreover, the improvement of adsorption capacity could play a synergistic coupling role to improve the intercalation kinetics of anions, in which has a high reversible capacity and excellent rate cycling property. Thus, positively charged EG with a large layer space (0.41 nm) demonstrates a high reversible capacity of 118.3 mAh/g at a current density of 1 A/g, along with a conspicuous rate performance of 74.8 mAh/g at 15 A/g. Additionally, as-prepared EG hybrids indicate superb cyclic stability with a retained capacity of 101.8 mAh/g over 10,000 cycles at 5 A/g. The electrostatic modification strategy and expansion of the layer space could facilitate the development of high property graphite cathode materials for AIBs.

Fe₂O₃ has been considered as a promising anode material for lithium-ion batteries (LIBs) owing to its high specific capacity. However, its sluggish charge transfer resulting from the poor electrical conductivity severely limits the electrochemical performance. In this work, an ultrathin Fe₃O₄ layer-coated Fe₂O₃ composite was fabricated through a facile one-step hydrothermal method with hydrazine hydrate as the reductant in an alkaline environment. Upon use as the anode for LIBS, the as-resulted Fe₂O₃@Fe₃O₄ composite achieves a high specific capacity of 1539.5 mA h g⁻¹ at a current density of 100 mA g⁻¹ and simultaneously maintains a high discharge capacity of 707.8 mAh g⁻¹ after 800 cycles at 1000 mA g⁻¹, outperforming the commercial Fe₂O₃ sample. Electrochemical characterizations reveal that the improved electrochemical performance can be attributed to the combined effects of higher theoretical specific capacity of Fe₂O₃ and superior electrical conductivity of Fe₃O₄.

Covalent organic frameworks (COFs), a newly emerging kind of porous material, have gained extensive attention due to their fascinating structural features. However, the superiority of COFs as electrochemical sensing materials has not yet been adequately explored. Herein, a new type of core–shell metal–organic framework (MOF)@COF composites are synthesized through in situ growth of TAPB-DMTP-COF on the pre-synthesized Ce-BDC core. The thickness of the COF shell can be controlled to 20–50 nm by adjusting the Ce-MOF mass. It is found that the obtained MOF@COF composite possesses a larger electrochemical active area and faster electron transfer kinetic than its single component. As a case application of this composite, it has been employed as a sensing material for voltammetric detection of metol, where a linear range from 0.1 − 200 μM and a detection limit of 30 nM have been obtained. This study provides a new strategy to synthesize COF-based electrode materials as well as to explore their electrochemical properties and applications.

Benefiting from the simple and low-cost fabrication of the one-step anti-solvent spin-coating process, the perovskite solar cells (PSCs) have a boost development. However, a great number of defects are generated during solution-fabrication process, retarding the development of PSCs seriously. In this study, the utilization of 4,5-dicyanoimidazole (DCI) as an additive for perovskite precursor solution was investigated. The presence of the double –CN groups in DCI facilitated the formation of Lewis acid-base coordination with unsaturated Pb²⁺ ions, as well as interaction with I^- anions by the –NH- moiety, resulting in the enhanced perovskite film crystallinity, the reduced grain boundaries, and a significant reduction in the defects density of the perovskite film. The decreased trap-assisted recombination and voltage open circuit (V_OC) losses in the PSC resulted in the improved photovoltaic performance of device treated by DCI molecule, the PCE increased from 19.59 % to 21.87 % significantly. Moreover, the unencapsulated device with DCI additive exhibited a remarkable 87.8 % retention of its initial PCE after exposure under 10–20 % relative humidity for 60 days, demonstrating an excellent stability than control device.

Organic electrode materials have been regarded as sustainable alternatives for sodium-ion batteries (SIBs) due to their high theoretical specific capacity, large reserves and wide sources from biomass. However, the variety of presently reported organic electrode materials is very limited and their essential electrochemical sodium storage behaviors also deserve further investigating. In this paper, we explore the electrochemical sodium storage behavior of a conjugated aromatic acid (4,4′-biphenyldicarboxylic acid, H₂bpdc) in esters and ethers-based electrolytes. The results illustrate that in esters-based electrolytes, H₂bpdc just shows limited capacity and poor electrochemical sodium storage kinetics. By contrast, in ethers-based electrolytes, H₂bpdc experiences a process similar to conversion type mechanism from pristine acid to sodium salt, displaying fast kinetics and delivers a high reversible capacity of 280 mA h g⁻¹. This research would provide basic and novel insights to the electrochemical sodium storage behaviors of promising organic electrode materials and accelerate the new materials exploration process for SIBs.

The abundant and renewable nature of lignin obtained from wood renders it as a sustainable carbon resource for energy storage applications. However, their environmentally unfavorable processing conditions and limited energy storage performance prohibit the use of lignin-based carbon materials' use as supercapacitor electrodes. The material's properties require advancement to overcome the limitation of low specific capacitances. In this study, we report on the impact on the electrochemical performance of inherently hydrophobic lignin-based carbon fibers (LCF) by subjecting them to a mild plasma treatment. The electrode’s capacitance was thus increased by 20%, with better rate capability and energy-power performance (11 Wh/kg and 0.8 kW/kg) in the KOH electrolyte. The quantified improvements were attributed to the capacitive functional groups, and enhanced surface wettability, which increased ion accessibility to active surface area improving charge-transfer ability to the surface with more additional functional groups. Remarkably, the selected plasma conditions introduced mostly desirable functional groups that limited any parasitic faradaic reactions prone to affect the device's long-term cycling stability and self-discharge characteristics. Furthermore, the impact of different inherent and introduced oxygen surface functional groups, including COO⁻, COH, CO, and CO, on the capacitive performance of these fibers at different device conditions (such as cycling and electrochemical activation) was investigated in different aqueous electrolytes. To ensure environmental favorability, the electrospinning of lignin fibers was conducted using a high molecular fraction of lignin without the inclusion of any fossil-based co-spinning polymers.

Antioxidant can protect body from free radical and dietary intake is a major source of antioxidants for human body. Therefore, it is particularly important to evaluate the antioxidant capacity of food and drink in daily diet. Herein, a label-free photoelectrochemical (PEC) sensor based on BiVO₄@graphene oxide (GO) hybrid has been developed for antioxidants analysis and applied it to antioxidant capacity detection of real samples. Five representative antioxidants including ascorbic acid (AA), caffeic acid (CA), chlorogenic acid (CHA), fisetin (FT) and quercetin (QT) were determined by this PEC sensor to acquire photocurrent response at different concentrations. This PEC sensor exhibited excellent sensitivity and anti-interference. Furthermore, antioxidant capacity of food samples was assessed utilizing this PEC sensor, indicating the practicability and accuracy of this PEC sensor. This study suggests that BiVO₄@GO composites constructed PEC sensor can provide a practical and fast method for detecting antioxidant capacity in the field of food.

CuO quantum dots (QDs)-embedded Cu₃(BTC)₂/CuO sugar gourd-like nanoarrays are successfully assembled on copper foil through a two-step wet-chemical growth method. As a free-standing anode for lithium-ion batteries, the resultant composite (Cu-BTC/QDs/CuO@Cu) delivers a high specific capacity of 813 mAh/g at a current density of 0.2 A/g after 150 cycles, and 452 mAh/g at 1.0 A/g after 500 cycles, demonstrating excellent cycling stability and rate performance. The superior energy storage capability is attributed to a synergistic effect from the individual components including the electro-active organic ligand, porous framework and CuO nanowires/QDs. As an efficient binder-free anode, Cu-BTC/QDs/CuO@Cu can be a promising candidate for the development of high-performance and cost-effective LIBs with exceptional energy density and power density capabilities.

Electrochemical reduction of nitrate to NH₃ is a very promising alternative reaction to the Haber-Bosch process, and it is necessary to develop the efficient electrocatalysts. In this study, a particle-support mode Co₃O₄ catalyst was synthesized with ZIF-67 as the precursor, and then dispersed on MoS₂ nanoflowers by hydrothermal method. The Co₃O₄ is anchored to MoS₂ by forming Co-S coordination bond. Furthermore, the particle-supported Co₃O₄ exhibits better performance than Co₃O₄ alone, as is manifested by higher Faradaic efficiencies and NH₃ yield rate at − 0.64 V (52.69% vs 32.03%; 4539.61 μg h⁻¹ mg⁻¹_cat vs 2048.63 μg h⁻¹ mg⁻¹_cat), lower energy barriers (0.96 eV vs 1.19 eV), and better electronic conductivity (Bandwidth: 0.581 eV vs 0.613 eV). In addition, this research provides an effective solution to solve the aggregation problem of metal oxide nanoparticles.