The growing demand for high-performance porous carbon materials has stimulated the development of new preparation and modification techniques. Activated carbon (AC) is a representative porous carbon material and there is a need to improve its physicochemical properties, especially porosity, to upgrade and expand its areas of applications. To produce ACs, activation is a key process, because it governs the porosity. In this article, a simple method for producing ACs with a highly developed pore structure is introduced. The idea for “pressurized physical activation” came from an understanding of physical and chemical activation mechanisms based on a recognition of microdomains, which are a basic structural unit of artificial carbon materials. This new activation method produced ACs with a specific surface area larger than 2600 m²/g, which is difficult to achieve by conventional atmospheric pressure physical activation. Although chemical activation can produce ACs with a higher degree of pore development and activation yield, the new method is considered an option to provide a high degree of pore development at a relatively low-cost. Together with a high porosity, the material produced had a characteristic pore size distribution and a high bulk density. Because of these features, the superior potential of the material was demonstrated as a relatively-inexpensive and high-performance adsorbent in an adsorption heat pump system using ethanol as the refrigerant.

In recent years, the demand for carbon fiber reinforced plastic (CFRP) with excellent mechanical properties and low weight has increased. At the same time, the amount of discarded CFRP is expected to increase. The recycling of CFRP is important to ensure its continued use in the face of increasingly stringent environmental regulations. Various recycling methods have been proposed, but the quality of the recycled carbon fiber (rCF) varies depending on the processing method and other factors. We have therefore developed two test methods to evaluate and ensure the quality of the rCF. These are (a) an improved fragmentation test that simultaneously evaluates the fiber/polymer interface shear strength and the fiber strength from a tensile test of a fiber-embedded polymer film, and (b) a fiber bundle tensile test that efficiently evaluates the strength distribution of rCF. We are also pursuing international standardization of these test methods to promote the use of rCF.

Over the past two decades, research on lithium–air batteries (LABs) has advanced significantly. Although many studies have used high-purity oxygen, the ultimate goal remains the development of batteries that can operate using oxygen directly from the air, while achieving an acceptable discharge–charge cycle performance. For this reason, these systems are referred to as LABs in this review. Among various research areas, the investigation of positive electrode materials has received the most attention. Recent years have seen a surge in the number of studies using in situ and operando measurement techniques, particularly those using time-resolved methods. As with other battery studies, relying solely on voltage and current data is insufficient to get the full picture. Instead, real-time monitoring of reaction states and structural changes in the electrodes, as well as the entire battery system, is imperative. A broad array of measurement techniques has been used for these analyses, including electrochemical methods, spectroscopic techniques, gravimetric analysis, X-ray analysis, imaging methods, and gas analysis. LABs are composed of three main components: the positive electrode, the negative electrode, and the electrolyte. The reactions occurring at the lithium surface and inside the positive electrode are highly complex. Therefore, selecting appropriate measurement methods that align with the research objectives is crucial for understanding these complex processes. LABs aim to achieve discharge–charge characteristics comparable to or surpassing those of lithium–ion batteries. This review focuses primarily on various in situ and operando measurements applied to the positive electrode, outlining how these methods help analyze the various phenomena in LABs and providing insights for future research directions.

Iron phthalocyanine (FePc), a molecular catalyst, has attracted considerable interest for its role in the oxygen reduction reaction (ORR) in fuel cells and various other applications. The incorporation of FePc on carbon materials increases its ORR activity considerably. However, the specific factors that affect this activity remain poorly understood because of a lack of data on the carbon supports. To improve the ORR catalytic performance of the Fe–N₄ structure, we systematically examined the structural parameters of the carbon supports that influence the ORR activity of FePc. The results show that all carbon-supported FePc catalysts had a higher ORR activity than bulk FePc powder. The ORR current was found to be related to the quantity of electrochemically active FePc, as determined by cyclic voltammetry, rather than the total amount of loaded FePc. In addition, the quantity of electrochemically active FePc increased with the size of the carbon layer. The onset potential for the ORR also varied with different carbon supports, with Ketjenblack (KB) having the highest value. Transmission electron microscopy and small-angle X-ray scattering measurements identified a hollow spherical structure for KB, with an average diameter of 44.8 nm. X-ray absorption fine structure analysis indicated that the FePc supported on KB was curved. Therefore, our study provides insights into the key factors related to carbon supports that increase the ORR activity of FePc.