A series of manganese-cerium mixed oxides were prepared by a glycothermal method, and the NO decomposition activities of the Ba-loaded Ce-Mn oxides were examined. Among the catalysts examined, the highest NO conversion was obtained on the BaO/Ce-Mn oxide catalyst with a Mn/(Ce+Mn) ratio of 0.25. The X-ray diffraction and Raman analyses indicated the formation of Ce-Mn oxide solid solutions with a cubic fluorite structure. The electron spin resonance analysis indicated the presence of paramagnetic Mn 2+ species in the composite catalysts. Incorporation of Mn 2+ in the fluorite structure of CeO 2 causes an increase in the concentration of oxygen vacancies, which play an important role in the NO decomposition activity of the catalysts. The catalysts were also characterized by X-ray photoelectron spectroscopy and temperature-programmed reduction techniques. Based on the results obtained, the relationship between the physical properties of the catalysts and their NO decomposition activities was discussed.

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Vertically aligned carbon nanotubes (CNTs) with controllable length and diameter fabricated by microwave plasma enhanced chemical vapor deposition (MPECVD) are of continuing interest for various applications. This paper describes the role of process gas composition as well as the pre‐coating catalytic layer characteristics. It is observed that nucleation of CNTs was significantly enhanced by adding nitrogen in the MPECVD process, which also promoted formation of bamboo‐like structures. The very first key step toward growth of aligned CNTs was the formation of high‐density fine carbon onion encapsulated metal (COEM) particles under a hydrogen plasma. Direct microscopic investigation of their structural evolution during the very early stages revealed that elongation, necking, and splitting of the COEM particles occurred accompanying the growth of CNTs, such that one of the split portions rode on the top of the growing tube while the remaining one resided on the root. Our results suggest that CNTs grow via the “tip‐growth” as well as “root‐growth” mechanisms.

We report on the preparation and field emission properties of quasi-aligned silicon carbon nitride ͑SiCN͒ nanorods. The SiCN nanorods are formed by using a two-stage growth method wherein the first stage involves formation of a buffer layer containing high density of nanocrystals by electron cyclotron resonance plasma enhanced chemical vapor deposition and the second stage involves using microwave plasma enhanced chemical vapor deposition for high growth rate along a preferred orientation. It should be noted that growth of the SiCN nanorods is self-mediated without the addition of any metal catalyst. Scanning electron microscopy shows that the SiCN nanorods are six-side-rod-shaped single crystals of about 1-1.5 m in length and about 20-50 nm in diameter. Energy dispersive x-ray spectrometry shows that the nanorod contains about 26 at. % of Si, 50 at. % of C, and 24 at. % of N. Characteristic current-voltage measurements indicate a low turn-on field of 10 V/m. Field emission current density in excess of 4.5 mA/cm 2 has been observed at 36.7 V/m. Moreover, SiCN nanorods exhibited rather stable emission current under constant applied voltage.

An electrically rechargeable zinc-air battery stack consisting of three single cells in series was designed using a novel structured bipolar plate with air-breathing holes. Alpha-MnO2 and LaNiO3 severed as the catalysts for the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). The anodic and cathodic polarization and individual cell voltages were measured at constant charge-discharge (C-D) current densities indicating a uniform voltage profile for each single cell. One hundred C-D cycles were carried out for the stack. The results showed that, over the initial 10 cycles, the average C-D voltage gap was about 0.94 V and the average energy efficiency reached 89.28% with current density charging at 15 mA· cm −2 and discharging at 25 mA· cm −2 . The total increase in charging voltage over the 100 C-D cycles was ~1.56% demonstrating excellent stability performance. The stack performance degradation was analyzed by galvanostatic electrochemical impedance spectroscopy. The charge transfer resistance of ORR increased from 1.57 to 2.21 Ω and that of Zn/Zn 2+ reaction increased from 0.21 to 0.34 Ω after 100 C-D cycles.The quantitative analysis guided the potential for the optimization of both positive and negative electrodes to improve the cycle life of the cell stack.