NiCo 2 O 4-based materials are promising for high-performance energy storage materials. Here, we report the synthesis of urchin-like NiCo 2 O 4 particles via the hydrothermal urea precipitation process, and studied the effect of urea concentrations on phase purity, microstructure, and electrochemical capacitor performance. NiCl 2 • 6H 2 O, CoCl 2 •6H 2 O and urea, were weighed as Ni:Co:urea = 1:2:[5, 10 or 15] in molar fraction, and they were dissolved in distilled water and hydrothermally heated at 140°C for 6 h. The three precursors were calcined at 350°C for 3 h in air atmosphere. The three products were mainly composed of 310¯m sized urchin-like particles. All the final samples had 520 nm sized mesopores and ³5070 m 2 /g of specific surface area, but the distributions of Ni and Co in the urchin-like particles were affected by the starting urea concentration. The sample of single-phase NiCo 2 O 4 from Ni:Co:urea = 1:2:15 showed the best electrochemical capacitor performance among the three urea concentrations.

This paper reports on the preparation of porous membranes consisting of plate-like β"-alumina grains and the evaluation for microfiltration properties. Porous β"-alumina-based ceramics were prepared by the solid-state reactive sintering of Na2CO3 and α-Al2O3 at 1100-1300 °C. To study the effect of impurities in the starting powder mixtures, LiF-doped membranes were also prepared. As for the water filtration test, the turbidity before and after the vacuum filtration was measured using sintered porous membranes. To simulate bacteria-contaminated water, a suspension of a commercial boehmite powder (D50 = 0.7 µm) in distilled water was used. The non-doped samples sintered at 1200 °C was composed of β"-alumina (84 wt.%) and β-alumina (16 wt.%) grains, and showed a good microfiltration performance; the turbidities before and after filtration were 894.4 NTU and 1.46 NTU, respectively.

Co 3 O 4 -based materials attract a lot of attention particularly for electrochemical applications. Here, we report a unique Co 3 O 4 hierarchical micro-and nanostructures (HMNS), viz., micrometer-sized mesoporous granules assembled with Co 3 O 4 facetted nanocrystals.CoCl 2 ·6H 2 O and urea (Co : urea = 2:15 in mol fraction) were dissolved in a water/ethanol mixed solution and hydrothermally heated at 160°C for 0.5 h, 4 h and 6 h. The three precursors were calcined at 350°C for 3 h in air atmosphere. The product via hydrothermal treatment for 4 h was composed of 'soft' cube-like granules, which actually was the assembly of well-facetted Co 3 O 4 microcrystals with pore-size distribution of ~10-100 nm. The other product via hydrothermal treatment for 6 h was composed of 'hard' cube-like granules, which actually was the assembly of fine and equiaxed Co 3 O 4 nanocrystals with narrow pore-size of distribution of ~10 nm. Macroand mesoporous Co 3 O 4 powders with controlled pore-size distribution were successfully synthesized via facile hydrothermal and post-thermal treatments. The 'soft' cube-like Co 3 O 4 granules (Co 3 O 4 HMNS) exhibited much higher electrochemical performance than a commercial Co 3 O 4 powder with the particle size of ~1-2 µm.

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