Chemical record最新文献

Proton exchange membrane fuel cells (PEMFCs) have proven to be a promising power source for various applications ranging from portable devices to automotive and stationary power systems. The production of PEMFC involves numerous stages in the value chain, with each stage presenting unique challenges and opportunities to improve the overall performance and durability of the PEMFC stack. These include steps such as manufacturing the key components such as the platinum-based catalyst, processing these components into the membrane electrode assemblies (MEAs), and stacking the MEAs to ultimately produce a PEMFC stack. However, it is also known that the break-in or conditioning phase of the stack plays a crucial role in the final performance as well as durability. It involves several key phenomena such as hydration of the membrane, swelling of the ionomer, redistribution of the catalyst and the creation of suitable electrochemical interfaces – establishment of the triple phase boundary. These improve the proton conductivity, the mass transport of reactants and products, the catalytic activity of the electrode and thus the overall efficiency of the FC. The cruciality of break-in is demonstrated by the improvement in performance, which can even be over 50 % compared to the initial state. The state-of-the-art approach for the break-in of MEAs involves an electrochemical protocol, such as voltage cycling, using a PEMFC testing station. This method is time-consuming, equipment-intensive, and costly. Therefore, new, elegant, and cost-effective solutions are needed. Nevertheless, the primary aim is to achieve maximum/optimal performance so that it is fully operational and ready for the market. It is therefore essential to better understand and deconvolute these complex mechanisms taking place during break-in/conditioning. Strategies include controlled humidity and temperature cycling, novel electrode materials and other advanced break-in methods such as air braking, vacuum activation or steaming. In addition, it is critical to address the challenges associated with standardisation and quantification of protocols to enable interlaboratory comparisons to further advance the field.

The cover picture shows the structure of some three-dimensional small molecular entities, such as highly-functionalized cyclopentanes and saturated azaheterocycles with multiple chiral centers, derived by chemical manipulations of Vince lactam. More details can be found in article number e2024000070 by Melinda Nonn, Santos Fustero, and Loránd Kiss. (DOl: 10.1002/tcr.202400070.

Front Cover: The cover shows the application status of superhydrophobic surfaces in combination with micro-nano structure and photodynamic capabilities in the field of antimicrobials. A similar combination of active and passive protection strategies is becoming possible in superhydrophobic surface applications. More details can be found in article number e202400065 by Ting Li, Yi Peng, and co-workers. (DOl: 10.1002/tcr.202400065.

The photocatalysis technique shows significant potential for wastewater degradation; however, the rapid recombination of photogenerated holes and electrons severely limits its photocatalytic efficiency. This situation necessitates the development of effective strategies to tackle these challenges. One well-documented approach is built-in electric field engineering in heterojunctions or composites, which has been shown to enhance electron transfer and thereby reduce the recombination of electrons and holes. This strategy has proven highly effective in significantly improving photocatalytic activity for the degradation of pollutants in wastewater. In this context, we summarize recent advancements in built-in electric field engineering in photocatalysts, highlighting the fundamentals and modifications of this approach, as well as its positive impact on photocatalytic performance in the degradation of wastewater pollutants.

Over three decades ago, two independent groups of investigators identified free D-aspartic and later D-serine in specific brain nuclei and endocrine glands. This finding revealed a novel, non-proteinogenic role of these molecules. Moreover, the finding that aged proteins from the human eye crystallin, teeth, bone, blood vessels or the brain incorporate D-aspartic acids to specific primary protein sequences fostered the hypothesis that aging might be related to D-amino acid isomerization of body proteins. The experimental confirmation that schizophrenia and neurodegenerative diseases modify plasma free D-amino acids or tissue levelsnurtured the opportunity of using D-amino acids as therapeutic agents for several disease treatments, a strategy that prompted the successful current application of D-amino acids to human medicine.

Green energy storage systems play a vital role in enabling a sustainable future by facilitating the efficient integration and utilization of renewable energy sources. The main problems related to two-dimensional (2D) materials are their difficult synthesis process, high cost, and bulk production, which hamper their performance. In recent years, MXenes have emerged as highly promising materials for enhancing the performance of energy storage devices due to their unique properties, including their high surface area, excellent electrical and thermal conductivity, and exceptional chemical stability. This paper presents a comprehensive scientific approach that explores the potential of MXenes for empowering green energy storage systems. Which indicates the novelty of the article. The paper reviews the latest advances in MXene synthesis techniques. Furthermore, investigates the application of MXenes in various energy storage technologies, such as lithium-ion batteries, supercapacitors, and emerging energy storage devices. The utilization of MXenes as electrodes in flexible and transparent energy storage devices is also discussed. Moreover, the paper highlights the potential of MXenes in addressing key challenges in energy storage, including enhancing energy storage capacity, improving cycling stability, and promoting fast charging and discharging rates. Additionally, industrial application and cost estimation of MXenes are explored. As the output of the work, we analyzed that HF and modified acid (LiF and HCl) are the established methods for synthesis. Due to high electrical conductivity, MXene materials are showing extraordinary results in energy storage and related applications. Making a composite hydrothermal method is one of the established methods. This scientific paper underscores the significant contributions of MXenes in advancing green energy storage systems, paving the way for a sustainable future driven by renewable energy sources. To facilitate the research, this article includes technical challenges and future recommendations for further research gaps in the topic.

Green hydrogen development plays an essential role in creating a sustainable and environmentally conscious society while reducing reliance on traditional fossil fuels. Proton Exchange Membrane Water Electrolysers (PEMWEs), are sensitive to water quality, with various impurities impacting their efficiency, the quality of the hydrogen produced, and the device‘s lifespan. High-purity water is required for PEM electrolyzers; Type II water, which is required for commercial electrolyzers, must have a resistivity greater than 1 MΩ cm, sodium, and chloride concentrations less than 5 μg/L, and total organic carbon (TOC) content less than 50 parts per billion. The majority of electrolyzers operate on freshwater, or total dissolved solids (TDS) <0.5 g/kg, whereas brackish, rainwater, wastewater, and seawater have TDSs of 1–35 g/kg, 0.01–0.15 g/kg, 0.5–2 g/kg, and 35–45 g/kg, respectively. This critical review offers, for the first time, a comprehensive overview of relevant impurities in operating electrolyzers and their impact. The findings of this study indicate that electrolysis-based H₂ processes are promising options that contribute to the H₂ production capacity but require improvements to produce larger competitive volumes. In addition, the main challenges and opportunities for generating, storing, transporting, and distributing hydrogen, as well as large-scale adoption are discussed.

Industry, agriculture, and a growing population all have a major impact on the scarcity of clean-water. Desalinating or purifying contaminated water for human use is crucial. The combination of thermal membrane systems can outperform conventional desalination with the help of synergistic management of the water-energy nexus. High energy requirement for desalination is a key challenge for desalination cost and its commercial feasibility. The solution to these problems requires the intermarriage of multidisciplinary approaches such as electrochemistry, chemical, environmental, polymer, and materials science and engineering. The most feasible method for producing high-quality freshwater with a reduced carbon footprint is demanding incorporation of industrial low-grade heat with membrane distillation (MD). More precisely, by using a reverse electrodialysis (RED) setup that is integrated with MD, salinity gradient energy (SGE) may be extracted from highly salinized MD retentate. Integrating MD-RED can significantly increase energy productivity without raising costs. This review provides a comprehensive summary of the prospects, unresolved issues, and developments in this cutting-edge field. In addition, we summarize the distinct physicochemical characteristics of the membranes employed in MD and RED, together with the approaches for integrating them to facilitate effective water recovery and energy conversion from salt gradients and freshwater.

A superhydrophobic surface is defined as having a contact angle exceeding 150 °C, indicating a remarkable ability to repel water. Generally, superhydrophobicity originates from the utilization of low-surface-energy materials with unique micro- and nanostructures. Superhydrophobic surfaces have gained considerable recognition and are widely employed in diverse areas for anti-icing, oil-water separation, anticorrosion, self-cleaning, blood-repellent, and antibacterial applications. These surfaces can greatly enhance industrial processes by yielding significant performance improvements. In this review, we introduce the basic theories that provide a foundation for understanding the hydrophobic properties of superhydrophobic surfaces. We then discuss current techniques for fabricating superhydrophobic coatings, critically analyzing their strengths and limitations. Furthermore, we provide an overview of recent progress in the application of superhydrophobic materials. Finally, we summarize the challenges in developing superhydrophobic materials and future trends in this field. The insights provided by this review can help researchers understand the basic knowledge of superhydrophobic surfaces and obtain the latest progress and challenges in the application of superhydrophobic surfaces. It provides help for further research and practical application of superhydrophobic surfaces.

Polycyclic heterocycles are the most common and critical structural motifs found in a variety of natural products, medicines, fertilizers, and advanced materials. Because of their widespread use in biologically active compounds and material chemistry, functionalised dibenzo heterocyclic compounds, especially dibenzofuran, dibenzothiophene, and carbazole derivatives, garnered much attention over time. Scientists are especially interested in elucidating more efficient techniques for developing these industrially essential compounds. Dibenzo-fused heterocycles can rapidly be synthesised using highly efficient transition metal-catalysed strategies as well as by economic metal-free reaction conditions. This review includes a detailed overview of the most recent significant synthetic techniques, both metal-catalysed and metal-free, to produce these industrially significant and medicinally important dibenzo-fused heterocycles.