A 3D NiCo2O4 nanowire array/carbon cloth (NCONW/CC) was employed as the cathode for Li-air batteries with a non-aqueous electrolyte. After its discharge, novel porous ball-like Li2O2 was found to be deposited on the tip of NiCo2O4 nanowires. The special structure of Li2O2 and active sites of catalysts are also discussed.

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Single-walled carbon nanotubes (SWNTs), since reported in 1993, [1] have been regarded as a promising material owing to unique structure-dependent properties, especially in nanoelectronics applications. [2,3] Therefore, tremendous efforts have been made to pursue the specific-chirality growth of SWNTs, including designing various catalysts [4][5][6][7][8][9] and growth process con-trolling. [10][11][12] Despite of some progresses made in chirality selective synthesis of SWNTs, the mechanism for the experiment successes is far from clarification.Currently, epitaxial growth from well-defined seeds, such as solid catalysts [13][14][15][16][17] and segments of carbon nanotubes, [18][19][20][21] has been thought to be the most promising strategy to realize this goal. At present, mainly high temperature solid catalysts were developed to realize structure-controlled growth of SWNTs. For example, using Mo 2 C and WC solid catalysts, a few (2m, m) SWNTs, such as (12, 6) and (8, 4), have been Currently, designing solid catalysts at high temperature is the main strategy to realize single-walled carbon nanotubes (SWNTs) with specific chirality, meaning it is very hard and challenging to create new catalysts or faces to fit new chirality. However, low temperatures make most catalysts solid, and developing solid catalysts at low temperature is desired to realize chirality control of SWNTs. A rational approach to grow SWNTs array with different chiralities on same solid Co catalysts at low temperature (650 °C) is herein put forward. Using solid Co catalysts, near-armchair (10, 9) tubes horizontal array with ≈75% selectivity and (12, 6) tubes array with ≈82% are realized by adopting a small amount of ethanol and large amount of CO respectively. (10, 9) tubes are enriched for thermodynamic stability and (12, 6) tubes for kinetics growth rate. Both kinds of tubes show a similar symmetry to the Co (1 1 1) face with threefold symmetry for the symmetry matching nucleation mechanism proposed earlier. This method provides a new strategy to study the nucleation mechanism and more possibilities for preparing new solid catalysts to control the structure of SWNTs.