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Abstract: Modified natural graphite is synthesized by surface coating and graphitizing process on the base of spherical natural graphite. The modified natural graphite is examined discharge capacity and coulombic efficiency for the initial charge–discharge cycle. Modification process results in marked improvement in electrochemical performance for a larger discharge capacity and better coulombic efficiency. The mechanism of the enhancement are investigated by means of X-ray powder diffraction, scan electron microscopy, and physical parameters examination. The proportion of rhombohedral crystal structure was reduced by the heat treatment process. The modified natural graphite exhibits 40mAhg−1 reduction in the first irreversible capacity while the reversible capacity increased by 16mAhg−1 in comparison with pristine graphite electrode. Also, it has an excellent capacity retention of ∼94% after 100 cycles and ∼87% after 300 cycles. [Copyright &y& Elsevier]

Abstract: Thin carbon nanotubes were synthesized by catalytic decomposition of CH4 over MoCoMgO catalyst. We obtained bundles of ordered nanotubes under hydrogen gas and disordered nanotubes under nitrogen gas over the same catalyst. The formation mechanism of nanotube bundles was discussed. The number of the tube walls was 2–5 with the corresponding diameters of 3–6 nm. We obtained a high production yield of 500 wt.% for the thin carbon nanotubes compared to the weight of the supplied catalyst. Moreover the duration of the hydrogen pretreatment was also found to have different effects on the yield of nanotubes under different carrier gases. [Copyright &y& Elsevier]