The forced convection methods on the rotating disk and ring-disk electrodes are carefully analyzed toward their use for calculation of the electron transfer number (n) for the oxygen reduction reaction (ORR) on various catalysts. It is shown that the widely used Koutechy–Levich (KL) method is not suitable to determine n for the ORR either theoretically or experimentally. From a theoretical viewpoint, the ORR is neither a single-step nor a one-way reaction and , therefore does not fulfill the assumptions of the KL method. From an experimental viewpoint, n is significantly dependent on the angular velocity of the rotating disk electrode, contradicting the assumption of constant n in the KL theory. An improved model is used to establish the aforementioned relationship between n and angular velocity. The recommended way to determine n for the ORR in alkaline electrolytes is to use the rotating ring-disk electrode with a properly biased Au ring, supplemented by the calibration of the collection efficiency.

Highly ordered mesoporous MoS2 with a high surface area and narrow pore‐size distribution is synthesized by a vacuum assisted impregnation route. The mesoporous MoS2 demonstrates an expanded d002 spacing of 0.66 nm. The mesoporous MoS2 electrode achieves an excellent high rate capacity of 608 mAh g−1 at the discharge current of 10 A g−1 (∼15C), which places MoS2 as a viable next generation high power source for electric vehicles.

We report a simple and effective way of fabricating high-quality carbon nanoscrolls (CNSs), using isopropyl alcohol solution to roll up monolayer graphene predefined on SiO(2)/Si substrates. Transmission electron microscopy studies reveal that the CNS has a tube-like structure with a hollow core surrounded by graphene walls 0.35 nm apart. Raman spectroscopy studies show that the CNS is free of significant defects, and the electronic structure and phonon dispersion are slightly different from those of two-dimensional graphene. Finally, the CNS-based device is fabricated, directly on the SiO(2)/Si substrate. Electrical-transport measurements show that its resistance is weakly gate-dependent but strongly temperature-dependent. In addition, the CNS can sustain a high current density up to 5 x 10(7) A/cm(2), indicating that it is a good candidate for microcircuit interconnects. The controlled fabrication of high-quality CNSs may open up new opportunities for both fundamental and applied research of CNSs.

An Fe-N-decorated hybrid material of carbon nanotubes (CNTs) grown in situ from porous carbon microblocks is designed and constructed. This material successfully combines the desirable merits for oxygen reduction reaction (ORR), such as highly active Fe-N species, good conductivity, large pore size, and sufficient surface area. These structural advantages give this low-priced material an outstanding catalytic performance for ORR closely comparable with Pt/C of the same quantity.

High-strength and conductive carbon nanotube (CNT) yarns are very attractive in many potential applications. However, there is a difficulty when simultaneously enhancing the strength and conductivity of CNT yarns. Adding some polymers into CNT yarns to enhance their strength will decrease their conductivity, while treating them in acid or coating them with metal nanoparticles to enhance their conductivity will reduce their strength. To overcome this difficulty, here we report a method to make high-strength and highly conductive CNT-based composite yarns by using a continuous superaligned CNT (SACNT) yarn as a conductive framework and then inserting polyvinyl alcohol (PVA) into the intertube spaces of the framework through PVA/dimethyl sulphoxide solution to enhance the strength of yarns. The as-produced CNT/PVA composite yarns possess very high tensile strengths up to 2.0 GPa and Young's moduli more than 120 GPa, much higher than those of the CNT/PVA yarns reported. The electric conductivity of as-produced composite yarns is as high as 9.2 × 10(4) S/m, comparable to HNO(3)-treated or Au nanoparticle-coated CNT yarns. These composite yarns are flexible, lightweight, scratch-resistant, very stable in the lab environment, and resistant to extremely humid ambient and as a result can be woven into high-strength and heatable fabrics, showing potential applications in flexible heaters, bullet-proof vests, radiation protection suits, and spacesuits.

We report a simple and continuous spinning method that combines twisting and shrinking processes to produce carbon nanotube yarns. In this method, a yarn freshly spun from a super-aligned carbon nanotube array is first twisted and then passes through a volatile solvent for shrinking. The as-produced yarn consists of densely packed carbon nanotubes, and thus has a tensile strength up to about 1 GPa. The tensile strength depends on the diameter and the twisting angle of the yarn. Different kinds of solvents, such as water, ethanol, and acetone, are used to shrink the twisted yarns, and acetone shows the best shrinking effect. The origin of the solvent shrinking effect is investigated. Our method is favorable for continuous mass production of high strength carbon nanotube yarns with a wide range of diameters, especially ultra-thin yarns.

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