Lithium–oxygen (Li–O₂) batteries have attracted considerable attention as prospective next-generation energy storage devices because of their highest theoretical energy density among all rechargeable batteries. Although fundamental researches focusing on the properties of the solid-state discharge products have been conducted to elucidate the factors that contribute to large charge overvoltages, many questions remain unanswered. In particular, due to the main discharge product being a peroxide, which cannot remain stable in the atmosphere, its formation process, properties, and the relationship between the surface structure and its reactivity are not fully understood. The present article aims to introduce the latest understanding of the reductive growth and oxidative decomposition processes of discharge products, particularly from a surface science perspective.

We developed an improved method for observing a clear magnetic contrast images using a commercially available scanning electron microscope (SEM). To obtain SEM images with a clear magnetic contrast using a type-I method, which utilizes changes in the number of detected signals of secondary electrons (SEs) deflected by a stray magnetic field of specimens, directional-selective detection of SEs is needed. By combining beam deceleration and tilting specimen, condition of directional-selective detection for SEs was achieved, resulting in improving the type-I magnetic contrast. The tilting deceleration condition was highly-sensitive to fine magnetic domain structures, and it was shown that fine magnetic domain structures can be visualized in perpendicular magnetization region of Nd-Fe-B alloy specimens. Furthermore, by combining two directional-selective SEM images in two orthogonal directions, magnetic contrast images without anisotropy comparable to those obtained by a Kerr microscopy and a Spin-SEM were obtained.

Additive manufacturing enables rapid prototyping of complex structures because it allows direct patterning without masks. Microfabrication using additive manufacturing has been applied to fabricate complex structures in microdevices such as micro-electro-mechanical systems. Our group has proposed laser assisted electrophoretic deposition (LAEPD) as a metal deposition method using a laser beam. This deposition processing technique combines laser trapping in colloidal solution and electrophoretic deposition, and is capable of directly deposition of metal nanoparticles on the substrates. In this paper, we introduce the principle and apparatus of the LAEPD for micro 3D metal printing method, as well as our previous works such as the spatial light modulator methods and in-process sintering method.

In recent years, DNP surface-enhanced NMR spectroscopy (DNP-SENS) has emerged as a unique analytical technique for characterizing surface structures at the atomic scale and has been applied to various materials. DNP-SENS experiments require polarization transfer “e^－ ⇒ ¹H ⇒ observation nuclei” ; however, this is challenging when the observation nuclei are quadrupolar nuclei, which account for approximately 74% of the periodic table. In this review, we introduce novel pulse sequences, adiabatic D-RINEPT, that enable polarization transfer from ¹H to the quadrupolar nuclei and demonstrate its application to metal oxides and sulfides.

We found that a mixture of rhombohedral boron monosulfide (r-BS) and graphene nanoplates (GNP) exhibits higher OER activity than commercially available ruthenium oxide. Furthermore, it was shown that when a mixture of r-BS and GNP was further supported on nickel foam, it did not deteriorate even after continuous operation at high output for more than 100 hours. Here, we will introduce these results in detail.

Electronic states of materials have been analyzed using angle-resolved photoelectron spectroscopy (ARPES), which requires a sample with a clean and flat surface. Here, we develop a series of the fabrication steps with a focused ion beam to extend the ARPES approach to microcrystals. A target can be cut from a sample of aggregated microcrystals, and firmly fixed onto a macroscopic substrate. We made a demonstration by fabricating a single-crystal micrographite, attached on a silicon substrate, and successfully prepared a surface that is clean enough to obtain the band dispersion curves using ARPES with a micro-focused beam. The present methodology can be applied to varieties of surface analyses and opens surface science of yet unexplored microcrystals, hidden in complex materials.