ChemElectroChem最新文献

The practical application of LiMn_1−xFe_xPO₄ as a cathode material is hindered considerably by its poor electronic conductivity and slow lithium-ion diffusion. In the present study, a uniform nitrogen-doped carbon coating on LiMn_0.7Fe_0.3PO₄ (LiMn_0.7Fe_0.3PO₄@NC) was achieved using ethylene diamine tetraacetic acid (EDTA) as a chelating agent and carbon source. The nitrogen-doped carbon layer enhanced the electronic conductivity and ionic diffusion of the LiMn_0.7Fe_0.3PO₄ cathode. Furthermore, the uniform carbon layer prevented metal ion dissolution and stabilized the crystal structure. The resulting LiMn_0.7Fe_0.3PO₄@NC-2 sample demonstrated superior performance with a specific capacity of 152.5 mAh g⁻¹ at 0.1 C and preserved 93.7 % of this capacity over 200 cycles at 1 C. Meanwhile, the LiMn_0.7Fe_0.3PO₄@NC-2 sample demonstrated a high Li⁺ diffusion coefficient (3.98×10⁻¹¹ cm² s⁻¹) and electrical conductivity (1.47×10⁻² S cm⁻¹). This study presents a novel approach to designing high-performance cathode materials using a cost-effective and straightforward process.

Anion exchange membrane (AEM) water electrolysis has emerged as a promising technology for producing hydrogen in a carbon-neutral economy. To advance its industrial application, performance evaluations of non-precious metal AEM electrolyzers with electrode areas of 25 cm² were conducted. The focus was on pure water operation, achieving a current density of 0.26 A cm⁻² at a voltage of 2.2 V. To gain a better understanding, the AEM electrolyzer was also operated in aqueous KOH, yielding 1.2 A cm⁻² at 2.2 V. By adding a liquid electrolyte and by varying cell components, causes of the occurring performance limitations and ways to improve the AEM electrolyzer were identified. Electrochemical impedance analysis showed that the activation loss at the anode due to sluggish OER kinetics was the limiting factor at low current densities. At higher current densities, which is the operating range of interest for industrial application, the ohmic resistance from the membrane was the dominant factor limiting high performance in pure water operation.

Catalytic hydrogenation is one of the most important transformations in both academia and industry. Compared with direct hydrogenation with molecular hydrogen or transfer hydrogenations with hydrides, electrohydrogenation provides an alternative and practical pathway using proton as the hydrogen source. In this review, we have summarized the recent advances in electrohydrogenations of polar and non-polar unsaturated compounds catalyzed by earth-aubundant metal complexes. In addition, we also present a detailed discussion of the scope and limitations, plausible mechanisms and the opportunities for further development.

Copper (Cu)-based chalcopyrite compounds are promising photoabsorber materials not only for solar cells but also for photoelectrochemical (PEC) systems for conversion of sunlight energy into chemical energy. PEC water splitting to generate hydrogen (H₂) is one of the most advanced technologies in a PEC system for the use of Cu-based chalcopyrite compounds. In this review, we firstly introduce crystallographic/energetic structures of Cu-based chalcopyrite compounds in view of their applications to PEC water splitting. Explanations for the operation of PEC water splitting using semiconductor materials are then overviewed. Based on these backgrounds, studies on PEC H₂ evolution over photocathodes based on CuInS₂ and CuGaSe₂ thin films that we have developed are reviewed in detail. For realizing efficient PEC H₂ evolution over these thin films, surface modifications with an n-type layer such as CdS and a catalytic site such as Pt deposit were found to be indispensable. Precise controls of p-n heterointerfaces formed by introducing an n-type layer should also be required to enhance PEC performance. Although PEC water splitting has not reached the required efficiency to be useful, effective combinations of appropriate surface and interface modifications should lead to further improvements of properties to be close to practical applications.

A special collection to celebrate the 70^th birthday of renowned molecular electrochemist Flavio Maran and his scientific contributions to the field and the electrochemical community.

Electrosynthetic reactions are performed in either custom-made reactors that are developed and machined in-house or commercially available systems that offer good reproducibility but come at a high cost. To bridge this divide between customizability and reproducibility, we have developed the Open-ESyn, which is a suite of 3D-printed components compatible with the popular ElectraSyn. This collection of parts increases the electrosynthesis that can be performed with the ElectraSyn, expanding, for example, the scale, temperature and the type of electrodes that can be used. The standardized reactor environment can be inexpensively recreated, thereby maintaining the reproducibility of the ElectraSyn ecosystem.

Through alteration of the polarity of DC plasma during the growth of carbon nanotubes in a PECVD reactor, significantly different morphologies of such species have been achieved. By using this approach, for the first time, both Half-aligned and Entangled structures were synthesized, along with Full-aligned carbon nanotubes, introducing three binder-free electrodes with various levels of tortuosity. The crucial parameter and influential effect of tortuosity in these three-dimensional nanostructure scaffolds for application in lithium-ion batteries were investigated. Previous research findings suggested that increasing the tortuosity of the conductive scaffolds leads to preferential accumulation of lithium at the top surface and causes the loss of capacity in subsequent charge-discharge cycles. Our finding reveals that there exists a trade-off between lithium-demand, capacity, and preferential accumulation of lithium at the top surface. Among the presented scaffolds, the Half-aligned MWCNTs was able to maintain a high capacity of 876.9 mAh/g over more than 300 cycles, and demonstrate capacity improvement during this period and excellent rate capability, even at a rate of 5 C. This capacity is almost three times that can be achieved with graphite, showcasing promising and outstanding results for carbon nanotubes.

The electrochemical reduction of CO₂ (CO₂RR) has gained significant attention due to its potential to reduce carbon emissions and produce valuable fuels and chemicals. CO₂RR is typically carried out in neutral or alkaline conditions, while challenges such as the carbon crossover and salt precipitate can hinder the practical application. Conducting CO₂RR in acidic media presents a promising method to address these issues, although it faces the problem of low efficiency and poor catalysis stability. Regulating the interface/surface microenvironment near the catalysts is crucial to minimize the competitive hydrogen evolution reaction and enhance CO₂RR activity and long-term stability. This review outlines recent advancements in acidic CO₂RR, emphasizing various microenvironment engineering strategies for optimizing the CO₂RR kinetics including electrolyte composition manipulation, catalyst design, electrode modification and cell configuration optimization. Additionally, the review addresses challenges into developing practical and cost-effective CO₂RR systems.

Lithium-metal solid-state batteries are attractive as next generation of Li-ion batteries due to higher safety and potentially higher energy density. To improve processability, solid-composite separators combine advantages of inorganic and polymer separators in hybrid structure. We report a systematic approach to fabricate composite separators with high content (90–95 wt %) of ceramic Li-ion conducting Li_6.45Al_0.05La₃Zr_1.6Ta_0.4O₁₂ (LLZO) powder embedded in a polyethylene oxide (PEO)-LiTFSI (20 : 1) matrix and understand factors affecting their properties and performance. Separators with good mechanical flexibility and excellent thermal stability were obtained, by optimizing materials and processing parameters. It was found that PEO molecular weight strongly influences the microstructure and electrochemical properties of the separators. In optimized separator with 90 wt % of LLZO and PEO with Mw 300,000 g/mol, a total ionic conductivity of 1.4×10⁻⁵ S/cm at 60 °C was achieved. The ceramic-rich separator showed excellent long-term cycling stability for more than 460 cycles (1000 h) at 0.1 mA/cm² in Li/Li symmetrical cells and achieved a critical current density of 0.25 mA/cm². The separators also enabled initial discharge capacities of more than 160 mAh/g in full cells with Li metal anode and composite solid-state LiNi_0.6Co_0.2Mn_0.2O₂ cathode, although rapid capacity fade was observed after 10 cycles in fully solid-state configuration.

The cover illustrates the colorful charged state of a bipolar redox molecule-based flow battery. In their Research Article, Samantha Macchi and co-workers highlight the performance impact of the “inactive” bridging group between two redox active moieties (DOI: 10.1002/celc.202400450).