Synthesis of Ultrahigh-Purity (6,5) Carbon Nanotubes Using a Trimetallic Catalyst.

Chirality-controlled synthesis of carbon nanotubes (CNTs) is one of the ultimate goals in the field of nanotube synthesis. At present, direct synthesis achieving a purity of over 90%, which can be called single-chirality synthesis, has been achieved for only two types of chiralities: (14,4) and (12,6) CNTs. Here, we realized an ultrahigh-purity (∼95.

Reduction of (100)-Faceted CeO for Effective Pt Loading.

Although the function and stability of catalysts are known to significantly depend on their dispersion state and support interactions, the mechanism of catalyst loading has not yet been elucidated. To address this gap in knowledge, this study elucidates the mechanism of Pt loading based on a detailed investigation of the interaction between Pt species and localized polarons (Ce) associated with oxygen vacancies on CeO(100) facets. Furthermore, an effective Pt loading method was proposed for achieving high catalytic activity while maintaining the stability.

Prominent Structural Dependence of Quantum Capacitance Unraveled by Nitrogen-Doped Graphene Mesosponge.

Porous carbons are important electrode materials for supercapacitors. One of the challenges associated with supercapacitors is improving their energy density without relying on pseudocapacitance, which is based on fast redox reactions that often shorten device lifetimes. A possible solution involves achieving high total capacitance (C), which comprises Helmholtz capacitance (C) and possibly quantum capacitance (C), in high-surface carbon materials comprising minimally stacked graphene walls.

Edge-Site-Free and Topological-Defect-Rich Carbon Cathode for High-Performance Lithium-Oxygen Batteries.

The rational design of a stable and catalytic carbon cathode is crucial for the development of rechargeable lithium-oxygen (LiO ) batteries. An edge-site-free and topological-defect-rich graphene-based material is proposed as a pure carbon cathode that drastically improves LiO battery performance, even in the absence of extra catalysts and mediators. The proposed graphene-based material is synthesized using the advanced template technique coupled with high-temperature annealing at 1800 °C.

Surfactant-mediated morphology evolution and self-assembly of cerium oxide nanocrystals for catalytic and supercapacitor applications.

Surfactant plays a remarkable role in determining the growth process (facet exposition) of colloidal nanocrystals (NCs) and the formation of self-assembled NC superstructures, the underlying mechanism of which, however, still requires elucidation. In this work, the mechanism of surfactant-mediated morphology evolution and self-assembly of CeO2 nanocrystals is elucidated by exploring the effect that surfactant modification has on the shape, size, exposed facets, and arrangement of the CeO2 NCs. It is directly proved that surfactant molecules determine the morphologies of the CeO2 NCs by preferentially bonding onto Ce-terminated {100} facets, changing from large truncated octahedra (mostly {111} and {100} exposed), to cubes (mostly {100} exposed) and small cuboctahedra (mostly {100} and {111} exposed) by increasing the amount of surfactant.

Anataselike Grain Boundary Structure in Rutile Titanium Dioxide.

The formation of nanoscale phases at grain boundaries in polycrystalline materials has attracted much attention, since it offers a route toward targeted and controlled design of interface properties. However, understanding structure-property relationships at these complex interfacial defects is hampered by the great challenge of accurately determining their atomic structure. Here, we combine advanced electron microscopy together with random structure searching to determine the atomic structure of an experimentally fabricated Σ13 (221) [11̅0] grain boundary in rutile TiO.

Ceramic phases with one-dimensional long-range order.

Solids are generally classified into three categories based on their atomic arrangement: crystalline, quasicrystalline and amorphous. Here we report MgO and NdO ceramic phases with special atomic arrangements that should belong to a category of solids different from these three well known categories by combining state-of-the-art atomic-resolution scanning transmission electron microscopy and first-principles calculations. The reported solid structure exhibits a one-dimensional (1D) long-range order with a translational periodicity and is composed of structural units that individually have atomic arrangements similar to those observed in coincidence-site lattice configurations present at grain boundaries.

Direct Imaging for Single Molecular Chain of Surfactant on CeO Nanocrystals.

Organic surfactant controls the synthesis of nanocrystals (NCs) with uniform size and morphology by attaching on the surface of NCs and further facilitates their assembly into ordered superstructure, which produces versatile functional nanomaterials for practical applications. It is essential to directly resolve the surfactant molecules on the surface of NCs to improve the understanding of surface chemistry of NCs. However, the imaging resolution and contrast are insufficient for a single molecule of organic surfactant on NCs.

Single-Crystal Growth of Cl-Doped n-Type SnS Using SnCl Self-Flux.

SnS is a promising photovoltaic semiconductor owing to its suitable band gap energy and high optical absorption coefficient for highly efficient thin film solar cells. The most significant carnage is demonstration of n-type SnS. In this study, Cl-doped n-type single crystals were grown using SnCl self-flux method.

Direct Determination of Atomic Structure and Magnetic Coupling of Magnetite Twin Boundaries.

Clarifying how the atomic structure of interfaces/boundaries in materials affects the magnetic coupling nature across them is of significant academic value and will facilitate the development of state-of-the-art magnetic devices. Here, by combining atomic-resolution transmission electron microscopy, atomistic spin-polarized first-principles calculations, and differential phase contrast imaging, we conduct a systematic investigation of the atomic and electronic structures of individual FeO twin boundaries (TBs) and determine their concomitant magnetic couplings. We demonstrate that the magnetic coupling across the FeO TBs can be either antiferromagnetic or ferromagnetic, which directly depends on the TB atomic core structures and resultant electronic structures within a few atomic layers.

Atomic-Scale Origin of the Quasi-One-Dimensional Metallic Conductivity in Strontium Niobates with Perovskite-Related Layered Structures.

The quasi-one-dimensional (1D) metallic conductivity of the perovskite-related SrNbO compounds is of continuing fundamental physical interest as well as being important for developing advanced electronic devices. The SrNbO compounds can be derived by introducing additional oxygen into the SrNbO perovskite. However, the physical origin for the transition of electrical properties from the three-dimensional (3D) isotropic conductivity in SrNbO to the quasi-1D metallic conductivity in SrNbO requires more in-depth clarification.

Mathematical analysis and STEM observations of arrangement of structural units in 〈001〉 symmetrical tilt grain boundaries.

A collaborative work between mathematics and atom-resolved scanning transmission electron microscopy (STEM) has been conducted. The grain boundary in a bicrystal of a simple rock-salt oxide can show a complicated arrangement of structural units, which can be well predicted by an algorithm utilizing the Farey sequence. The estimated arrangements had a nice agreement with those observed by STEM in atomic-scale up to several tens of nanometers.

Interfacial Atomic Structure of Twisted Few-Layer Graphene.

A twist in bi- or few-layer graphene breaks the local symmetry, introducing a number of intriguing physical properties such as opening new bandgaps. Therefore, determining the twisted atomic structure is critical to understanding and controlling the functional properties of graphene. Combining low-angle annular dark-field electron microscopy with image simulations, we directly determine the atomic structure of twisted few-layer graphene in terms of a moiré superstructure which is parameterized by a single twist angle and lattice constant.