Electrochemical science advances最新文献

The review discloses the historical and technological evolution of enzyme-based field-effect transistors (EnFETs) underlying the importance of gate electrode modification toward the implementation of novel FETs configurations such as extended-gate FET (EG-FETs) or EG organic FETs (EG-OFETs). The working principle of the EnFETs as postulated by Bergveld in 1970, who defined the EnFET as an ion-selective FET (ISFET) modified with enzyme-membrane, is also discussed considering the analytical equations related to the EnFET output response. For each category, namely EnFETs, EG-FETs, and EG-OFETs, we reviewed the key devices’ configurations that addressed the research in this field in the last 40 years with particular attention to the analytical figures of merit.

Over the past decades, considerable development and improvement can be observed in the area of the ion-sensitive field-effect transistor (ISFET) for biosensing applications. The mature semiconductor industry provides a solid foundation for the commercialization of the ISFET-based sensors and extensive research has been conducted to improve the performance of ISFET, with a special research focus on the materials, device structures, and readout topologies. In this review, the basic theories and mechanisms of ISFET are first introduced. Research on ISFET gate materials is reviewed, followed by a summary of typical gate structures and signal readout methods for the ISFET sensing system. After that, a variety of biosensing applications including ions, deoxyribonucleic acid, proteins, and microbes are presented. Finally, the prospects and challenges of the ISFET-based biosensors are discussed.

A lithium-ion battery (LIB) cathode comprises three major components: active material, electrical conductivity additive, and binder. The combination of binder and electrical conductivity additive leads to the formation of composite clusters known as the carbon binder domain (CBD) clusters. Preparation of a LIB cathode strongly influences the dispersion of the above-mentioned constituents leading to the formation of distinct pore and electrical conduction networks. The resulting structure thus governs the performance of LIBs. The presence of CBD is essential for the structural integrity and sufficient electrical conductivity of the LIB cathode. However, CBD abundance in LIB cathodes leads to unfavorable gravimetrical and volumetrical consequences owing to its electrochemical inertness. Increasing CBD content adds to the weight of the LIBs, thus negatively impacting the energy density. Furthermore, increased electrical conductivity is won at a cost of ionic conductivity as CBD clusters breach the pore networks in the cathode microstructure. The following study establishes a link between the various possibilities of CBD cluster size and fractal dimension that may eventualize during the mixing process of slurry preparation to the resulting microstructural properties and hence to the performance of LIBs by means of idealized cathode geometries. Since the performance determining processes occur at the microstructural scale, which are often very tedious to study via experimental research, the study makes use of spatially resolving microstructural, numerical, simulations. The results demonstrate that the CBD cluster size has a strong influence on the cathode microstructure. The CBD cluster fractal dimension on the other hand displayed a minor influence on the structural properties of the cathode, and the size of the cluster primary particles was shown to be the dominant factor. Finally, performance evaluation simulations confirmed the trends seen in structural properties with changing cluster size and fractal dimension.

A direct current in an electrochemical cell with a diluted liquid electrolyte leads to the displacement of ions within the solvent, while diffusion works against the resulting concentration differences. This study aims to experimentally evaluate a physicochemical ion transport model (source code provided) that describes current-driven concentration gradients in diluted electrolytes. Hereto, an aqueous 0.1 M CuSO₄ electrolyte between metallic copper electrodes serves as an experimental test system. Spatially resolved optical measurements are used to monitor the evolution of the ion concentration gradient in the electrolyte. Moreover, measured limited currents are related to computationally modeled concentration gradients. A constant parameterization of the diffusion coefficient, molar conductivity and ion transport number lead to a slight overestimation of the cathodic ion depletion and cell resistance, whereas a literature data based concentration dependent parameterization matches better to the measured data. The limited current is considered under a computational parameter variation and thereby related to the physicochemical impact of different electrolyte properties on the ion transport. This approach highlights the differences between purely diffusion limited currents and the limited current resulting from the combined electric field and diffusion driven ion motion. A qualitative schematic sketch of the physical mechanisms of the ion movement is presented to illustrate the current driven ion displacement in liquid electrolytes.

Efficiently improving the moisture stability of β-Li₃PS₄ materials could significantly reduce production costs and eventually enable the mass application. Nanoporous multiphase β-Li₃PS₄ materials prepared via solvent-assistant routes usually contain solvent or solvent decomposition segments associated with the amorphous Li₃PS₄ phase in their structures. Herein, the solvent ethyl propionate (EP) remains in the β-Li₃PS₄ even after 220 h of annealing at 220°C. The possibility of tuning the moisture stability of β-Li₃PS₄ by adjusting the content of the solvent is investigated by environmental scanning electron microscopy (ESEM) combined with other structural analysis techniques. The results demonstrated that the hydrogen-containing amorphous Li₃PS₄ not only stabilizes the β-phase at room temperature but also improves the moisture stability of the material. Although the rapid hydrolysis occurs on the surface of solvent-containing β-Li₃PS₄ materials under ambient conditions within 10 s, with 4 wt% EP content, the material can be exposed to 1.6% relative humidity (R.H.) for at least 8 h without any structural or microstructural change. Even with the lower amount of EP (1.2 wt%) in the Li₃PS₄ structure, the material can withstand 1% R.H. for more than 8 h, which allows the material to be manufactured in a dry room. Our observation proposes a simple method to slightly modify the moisture stability of β-Li₃PS₄ to match the different manufacturing conditions.

Glycerol is a cheap, non-toxic, and renewable by-product of the rapid expansion of biodiesel and soap producers around the world. Glycerol electroforming is a method of oxidizing glycerol into valuable chemicals of interest to the pharmaceutical, cosmetics, polymer, and food industries. One of the technologies that have been studied over the past decades is to couple glycerol oxidation with the production of pure hydrogen in an electrolysis cell (so-called electrolyzer), which has shown the advantage of consuming a much lower theoretical amount of electricity than conventional water electrolysis. The efficiency of this device is influenced by the nature, structure, and composition of the electrode material. This mini-review concerns the understanding of glycerol electro-oxidation, a brief state of the art of nanomaterials currently used to prepare electrode materials, and some results concerning the performance of electrolyzers in alkaline conditions that combine the efficient production of value-added chemicals and hydrogen.

Peptide nucleic acids (PNAs) are neutral mimics of natural DNA and RNA biopolymers that have caught the attention of researchers working on the identification of specific sequences of nucleobases in DNA/RNA strands. For this purpose, specific analytical protocols need to be developed to optimize the nucleic acid recognition ability of PNAs, exploiting both the high intrinsic affinity of PNA/DNA(RNA) couples as well as suitable markers, either linked to the PNA backbone or properly interacting with it in the working medium. In this context, the paper reports on phthalimide and 4-nitrophthalimide as two cheap, metal-free electroactive markers covalently bound to the pseudo-peptide backbone of a PNA decamer. After a preliminary characterization of the markers, as such and in PNA conjugates, attention has been moved toward the optimization of the detectability of the labeled PNA decamers in aqueous solutions. Exploiting the potentiometric stripping analysis on hanging mercury drop electrode it has been possible to reach satisfactory detection limits of ca. 10 nM avoiding the use of expensive transition metal complexes as labels and/or of co-reagents.

Electrochemical synthesis of hydrogen peroxide (H₂O₂) via a two-electron (2e^–) oxygen reduction reaction (ORR) has emerged as a sustainable synthesis route compared to the anthraquinone oxidation synthesis process. Ba_0.5Sr_0.5Fe_(1-x)Cu_xO_3-δ perovskite is a particularly interesting electrocatalyst for ORR applications owing to its doping flexibility. In this study, we use experimental and computation approaches to study Ba_0.5Sr_0.5FeO_3-δ with and without copper doping at the B-site for 2e^– ORR. Our electrochemical measurements in oxygen-saturated alkaline solution show that the selectivity of perovskite electrocatalyst increases from 30% to 65% with (0.05) copper doping in the B-site and the onset potential is decreased. Density functional theory calculations are used to unravel the role of copper in driving high activity and selectivity toward 2e^– ORR. Site-specific engineering of Ba_0.5Sr_0.5FeO_3-δ by copper doping in the B-site exposed unique adsorption sites with improved activity and selectivity for H₂O₂ formation.

Homogeneous, aqueous solutions of the natural compound riboflavin were investigated for their electrocatalytic oxygen to hydrogen peroxide (H₂O₂) reduction performance using cyclic voltammetry and electrolysis. In addition to pH dependencies, interestingly the choice of carbon-based electrode material had a strong impact on the electrocatalytic performance. Therefore, the three electrode materials, glassy carbon, carbon paper (CP), and carbon felt were electrochemically compared and afterwards investigated with scanning electron microscopy. Attributed to the deprotonation of riboflavin, pH = 13 was identified as the best performing condition. Using CP at pH = 13, the addition of riboflavin enhanced the H₂O₂ production by a factor of 14 up to 355 μmol after 6 h at an average faradaic efficiency of around 80%.