Novel peapod-like Co@carbon and Co(3)O(4)@carbon composite nanostructures have been successfully fabricated for the first time based on rational design and elaborate analyses. The nanostructures exhibit the unique feature of Co or Co(3)O(4) nanoparticles (20 nm) encapsulated inside and well-graphitized carbon layers coating outside. The peapod-like Co@carbon and Co(3)O(4)@carbon nanostructures exhibit intriguing morphologies, architectures, and chemical compositions. What is more important, the unique morphologies, architectures, and chemical compositions will lead to perfect performances in many applications. In this paper, a good example of Li-ion battery testing is given to demonstrate the superior stability and rate capability of the Co(3)O(4)@carbon. The peapod-like nanostructure of Co(3)O(4)@carbon demonstrates very high specific capacity (around 1000 mAh/g at the charge/discharge rate of 1C) and wonderful cyclability (at least 80% retention is available when cycled back from very high charge/discharge rate of 10C) during the galvanostatic cycling, indicating it as the promising candidate for Li-ion batteries' anodes. Additionally, the excellent electrochemical performance is significantly associated with the unique architecture in the samples, which verifies the feasibility of rational design of hierarchical materials for the actual applications. Meanwhile, the Co@carbon and Co(3)O(4)@carbon nanostructures demonstrate the regular and uniform distribution of magnetic nanoparticles in well-graphitized carbon fiber, which is a great achievement in the field of monodispersing and isolating magnetic nanoparticles. The prepared samples can also be potentially applied in other fields, such as gene delivery, catalysis, and magnetism.

A novel catalyst, Co-PPy-TsOH/C, for oxygen reduction reaction (ORR) in proton exchange membrane fuel cells (PEMFCs) was prepared by pyrolyzing cobalt salt and p-toluenesulfonic acid (TsOH)-doped polypyrrole-modified carbon support in an inert atmosphere. The characteristics and electrocatalytic activities of Co-PPy-TsOH/C were analyzed with various techniques, including Raman spectroscopy, elemental analysis, rotating ring disk electrode analysis, and a single H(2)-O(2) PEMFC, and compared with those of undoped catalyst Co-PPy/C. The results showed that doping TsOH introduces larger N and S contents in Co-PPy-TsOH/C, leading to much better electrocatalytic performance for ORR than Co-PPy/C, and that Co-PPy-TsOH/C is more likely to follow a four-electron-transfer reaction to reduce oxygen directly to H(2)O. The performance of PEMFCs with Co-PPy-TsOH/C as cathode catalyst is better than that with Co-PPy/C, and the resulting maximum output power density of 203 mW cm(-2) is a substantial improvement over the best values reported in the literature with Co-PPy/C-based cathode catalyst. This implies that doping TsOH is a valuable method to improve the catalytic activity of Co-PPy/C and that Co-PPy-TsOH/C is a promising cathode catalyst for PEMFCs. The function and mechanism of doping have also been analyzed and the configurations of PPy-TsOH/C and Co-PPy-TsOH/C proposed.

In this article, we introduce a novel two-dimensional (2D) functional Co 3 O 4 nanostructure, ''nanomesh'', which possesses the highest surface area (382 m 2 g À1 ) as compared to the other Co 3 O 4 nanostructures, well-crystallized features, thickness of no more than 10 nm and a void space diameter below 6.0 nm. These structural characteristics of the nanomesh are well-suited for lithium-ion battery (LIBs) applications. In initial tests, high specific capacity (1800 mAh/g), good rate capability (above 380 mAh/g at a discharging rate of 1000 mA g À1 over 50 cycles) and stable cyclability (up to 100 cycles) have been demonstrated. In addition, the dominant ( 112) crystal plane in the nanomesh has much higher surface energy than the conventional ( 111) and ( 100) crystal planes, leading to higher activity in supercapacitors. The Co 3 O 4 nanomesh demonstrated in this research could be successfully utilized in energy and environmental applications, such as selective catalysis, gene delivery and gas or biological sensing, besides the application in electrochemical energy storage shown in this work. More importantly, the synthesis strategy used in this research can possibly be extended to other material systems as a general approach to fabricate 2D mesoporous oxides.

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